Chiara Neto

Patterned Polymer Coatings Increase the Efficiency of Dew Harvesting

Publisher: American Chemical Society (ACS)

Date: 03-03-2017

DOI: 10.1021/ACSAMI.6B16248

Abstract: Micropatterned polymer surfaces, possessing both topographical and chemical characteristics, were prepared on three-dimensional copper tubes and used to capture atmospheric water. The micropatterns mimic the structure on the back of a desert beetle that condenses water from the air in a very dry environment. The patterned coatings were prepared by the dewetting of thin films of poly-4-vinylpyridine (P4VP) on top of polystyrene films (PS) films, upon solvent annealing, and consist of raised hydrophilic bumps on a hydrophobic background. The size and density distribution of the hydrophilic bumps could be tuned widely by adjusting the initial thickness of the P4VP films: the diameter of the produced bumps and their height could be varied by almost 2 orders of magnitude (1-80 μm and 40-9000 nm, respectively), and their distribution density could be varied by 5 orders of magnitude. Under low subcooling conditions (3 °C), the highest rate of water condensation was measured on the largest (80 μm diameter) hydrophilic bumps and was found to be 57% higher than that on flat hydrophobic films. These subcooling conditions are achieved spontaneously in dew formation, by passive radiative cooling of a surface exposed to the night sky. In effect, the pattern would result in a larger number of dewy nights than a flat hydrophobic surface and therefore increases water capture efficiency. Our approach is suited to fabrication on a large scale, to enable the use of the patterned coatings for water collection with no external input of energy.

Boundary flow on end-grafted PEG brushes

Publisher: Royal Society of Chemistry (RSC)

Date: 2016

DOI: 10.1039/C5SM02546J

Abstract: We investigated the boundary conditions for flow of a Newtonian liquid over soft interfaces by measuring hydrodynamic drainage forces with colloid probe atomic force microscopy in a viscous liquid. The investigated soft surfaces are end-grafted brushes of thiolated poly(ethylene glycol) (PEG), of molecular weight 1k and 30k, grafted-to gold. The conditions for brush preparation were optimized as to meet the stringent conditions required for surface force measurements, namely reproducible and uniform surface composition and roughness. The fit of a slip model to the experimental data returned a slip length of 16 nm on the PEG 1k brush and 25 nm on the PEG30k brush. The slip length can be interpreted as a penetration length, which accounts for flow within the top half of the brush for the PEG30k case, and within the brush and surface roughness for the PEG1k case. These findings confirm earlier simulation studies by our group on the flow of liquids within polymer brushes.

High Glass Transition Temperature Fluoropolymers for Hydrophobic Surface Coatings via RAFT Copolymerization

Publisher: CSIRO Publishing

Date: 2016

DOI: 10.1071/CH15787

Abstract: The preparation of polymer thin films or surface coatings that display a static water contact angle ° often requires hierarchical roughness features or surface functionalization steps. In addition, inherently hydrophobic polymers such as fluoropolymers often possess low glass transition temperatures, reducing their application where thermal stability is required. Herein, the first reported synthesis of 2,3,4,5,6-pentafluorostyrene (PFS) and N-phenylmaleimide (NMI) via reversible addition–fragmentation chain-transfer (RAFT)-mediated free radical polymerization is presented, with a view towards the preparation of inherently hydrophobic polymers with a high glass transition temperature. A suite of copolymers were prepared and characterized, and owing to the inherent rigidity of the maleimide group in the polymer backbone and π–π interactions between adjacent PFS and NMI groups, very high glass transition temperatures were achieved (up to 180°C). The copolymerization of N-pentafluorophenylmaleimide was also performed, also resulting in extremely high glass transition temperature copolymers however, these polymers did not exhibit characteristics of being under RAFT control. Thin films of PFS-NMI copolymers exhibited a static contact angle ~100°, essentially independent of the amount of NMI incorporated into the polymer.

Evaluating medical device and material thrombosis under flow: current and emerging technologies

Publisher: Royal Society of Chemistry (RSC)

Date: 2020

DOI: 10.1039/D0BM01284J

Abstract: This review highlights the importance of flow in medical device thrombosis and explores current and emerging technologies to evaluate dynamic biomaterial Thrombosis in vitro .

Self-assembled porphyrin microrods and observation of structure-induced iridescence

Publisher: Royal Society of Chemistry (RSC)

Date: 2010

DOI: 10.1039/B917695K

Soft–hard Janus nanoparticles for polymer encapsulation of solid particulate

Publisher: Royal Society of Chemistry (RSC)

Date: 2020

DOI: 10.1039/D0PY00845A

Abstract: Janus nanoparticles with soft lobes can self-assemble on the surface of solid substrates in aqueous phase and coalesce to form a complete polymer shell encapsulating the entire solid substrate.

Thermally cross-linked PNVP films as antifouling coatings for biomedical applications

Publisher: American Chemical Society (ACS)

Date: 20-07-2010

DOI: 10.1021/AM100406J

Abstract: Protein repellent coatings are widely applied to biomedical devices in order to reduce the nonspecific adhesion of plasma proteins, which can lead to failure of the device. Poly(N-vinylpyrrolidone) (PNVP) is a neutral, hydrophilic polymer with outstanding antifouling properties often used in these applications. In this paper, we characterize for the first time a cross-linking mechanism that spontaneously occurs in PNVP films upon thermal annealing. The degree of cross-linking of PNVP films and their solubility in water can be tailored by controlling the annealing, with no need for additional chemical treatment or irradiation. The physicochemical properties of the cross-linked films were investigated by X-ray photoelectron spectroscopy, infrared spectroscopy, neutron and X-ray reflectometry, ellipsometry, and atomic force microscopy, and a mechanism for the thermally induced cross-linking based on radical formation was proposed. The treated films are insoluble in water and robust upon immersion in harsh acid environment, and maintain the excellent protein-repellent properties of unmodified PNVP, as demonstrated by testing fibrinogen and immunoglobulin G adsorption with a quartz crystal microbalance. Thermal cross-linking of PNVP films could be exploited in a wide range of biotechnological applications to give antifouling properties to objects of any size, essentially making this an alternative to high-tech surface modification techniques.

Dynamics of hole growth in dewetting polystyrene films

Publisher: Elsevier BV

Date: 08-2004

DOI: 10.1016/J.PHYSA.2004.03.049

In situ calibration of colloid probe cantilevers in force microscopy: Hydrodynamic drag on a sphere approaching a wall

Publisher: American Chemical Society (ACS)

Date: 23-08-2001

DOI: 10.1021/LA010424M

Nanostructure Explains the Behavior of Slippery Covalently Attached Liquid Surfaces

Publisher: Wiley

Date: 04-09-2023

DOI: 10.1002/ANIE.202308008

Abstract: Slippery covalently‐attached liquid surfaces (SCALS) with low contact angle hysteresis (CAH, ◦) and nanoscale thickness display impressive anti‐adhesive properties, similar to lubricant‐infused surfaces. Their efficacy is generally attributed to the liquid‐like mobility of the constituent tethered chains. However, the precise physico‐chemical properties that facilitate this mobility are unknown, hindering rational design. This work quantifies the chain length, grafting density, and microviscosity of a range of polydimethylsiloxane (PDMS) SCALS, elucidating the nanostructure responsible for their properties. Three prominent methods are used to produce SCALS, with characterization carried out via single‐molecule force measurements, neutron reflectometry, and fluorescence correlation spectroscopy. CO2 snow‐jet cleaning was also shown to reduce the CAH of SCALS via a modification of their grafting density. SCALS behavior can be predicted by reduced grafting density, Σ, with the lowest water CAH achieved at Σ ≈ 2. This study provides the first direct examination of SCALS grafting density, chain length, and microviscosity and supports the hypothesis that SCALS properties stem from a balance of layer uniformity and mobility.

The effect of surfactant adsorption on liquid boundary slippage

Publisher: Elsevier BV

Date: 08-2004

DOI: 10.1016/J.PHYSA.2004.03.044

Interfacial flow of simple liquids on polymer brushes: Effect of solvent quality and grafting density

Publisher: American Chemical Society (ACS)

Date: 20-07-2012

DOI: 10.1021/MA300880Y

Imaging soft matter with the atomic force microscope: Cubosomes and hexosomes

Publisher: American Chemical Society (ACS)

Date: 24-04-1999

DOI: 10.1021/JP984551B

Convergent evolution of skin surface microarchitecture and increased skin hydrophobicity in semi-aquatic anole lizards

Publisher: The Company of Biologists

Date: 10-2021

DOI: 10.1242/JEB.242939

Abstract: Animals that habitually cross the boundary between water and land face specific challenges with respect to locomotion, respiration, insulation, fouling and waterproofing. Many semi-aquatic invertebrates and plants have developed complex surface microstructures with water-repellent properties to overcome these problems, but equivalent adaptations of the skin have not been reported for vertebrates that encounter similar environmental challenges. Here, we document the first evidence of evolutionary convergence of hydrophobic structured skin in a group of semi-aquatic tetrapods. We show that the skin surface of semi-aquatic species of Anolis lizards is characterized by a more elaborate microstructural architecture (i.e. longer spines and spinules) and a lower wettability relative to closely related terrestrial species. In addition, phylogenetic comparative models reveal repeated independent evolution of enhanced skin hydrophobicity associated with the transition to a semi-aquatic lifestyle, providing evidence of adaptation. Our findings invite a new and exciting line of inquiry into the ecological significance, evolutionary origin and developmental basis of hydrophobic skin surfaces in semi-aquatic lizards, which is essential for understanding why and how the observed skin adaptations evolved in some and not other semi-aquatic tetrapod lineages.

Aligned Droplet Patterns by Dewetting of Polymer Bilayers

Publisher: American Chemical Society (ACS)

Date: 05-07-2018

DOI: 10.1021/ACS.MACROMOL.8B00620

Protein micropatterns by PEG grafting on dewetted PLGA films

Publisher: American Chemical Society (ACS)

Date: 22-09-2014

DOI: 10.1021/LA5018592

Abstract: The ability to control protein and cell positioning on a microscopic scale is crucial in many biomedical applications, such as single cell studies. We have developed and investigated the grafting of poly(ethylene glycol) (PEG) brushes onto poly(d,l-lactide-co-glycolide) (PLGA) thin films, which can be micropatterned by exploiting their spontaneous dewetting on top of polystyrene (PS) films. Dense PEG brushes with excellent protein repellence were achieved on PLGA by using cloud point grafting conditions, and selective adsorption of proteins on the micropatterned substrates was achieved by exploiting the different affinity protein adsorption onto the PEG brushes and the PS holes. PEG-grafted PLGA films showed better resistance against spontaneous degradation in buffer than bare PLGA films, due to passivation by the thin PEG coating. The simplicity of dewetting and subsequent grafting approaches, coupled with the ability to coat and pattern nonplanar substrates give rise to possible applications of PEG-grafted PLGA films in single cell studies and cell cultures for tissue engineering.

Reliable Measurements of Interfacial Slip by Colloid Probe Atomic Force Microscopy. I. Mathematical Modeling

Publisher: American Chemical Society (ACS)

Date: 04-05-2011

DOI: 10.1021/LA2007809

Abstract: We developed a stable spread-sheet algorithm for the calculation of the hydrodynamic forces measured by colloid probe atomic force microscopy to be used in investigations of interfacial slip. The algorithm quantifies the effect on the slip hydrodynamic force for factors commonly encountered in experimental measurements such as nanoparticle contamination, nonconstant drag force due to cantilever bending that varies with different cantilevers, flattening of the microsphere, and calibration at large separations. We found that all of these experimental factors significantly affect the fitted slip length, approximately in the order listed. Our modeling is applied to fit new experimental data reproducibly. Using this new algorithm, it is shown that the fitting of hydrodynamic theories to experimental data is reliable and the fitted slip length is accurate. A "blind test" protocol was developed that produces a reliable estimate of the fitting error in the determination of both the slip length and spring constant. By this blind test, we estimate that our modeling determines the fitted slip length with an average systematic error of 2 nm and the fitted spring constant with a 3% error. Our exact calculation of the drag force may explain previous reports that the fitted slip length depends upon the shape and spring constant of the cantilever used to perform the measurements.

Challenges and opportunities for innovation in bioinformed sustainable materials

Publisher: Springer Science and Business Media LLC

Date: 04-10-2023

DOI: 10.1038/S43246-023-00405-Z

Host–guest interactions of catechol and 4-ethylcatechol with surface-immobilized blue-box molecules

Publisher: Royal Society of Chemistry (RSC)

Date: 2019

DOI: 10.1039/C9TA00556K

Abstract: Surface-immobilized Blue Box molecules remove large amounts of the highly toxic catechol and 4-ethylcatechol from aqueous media, catalyzing the formation of a thin film of poly(catechol).

Micropatterning of proteins using dewetting

Publisher: IEEE

Date: 2006

DOI: 10.1109/ICONN.2006.340601

Robust grafting of PEG-methacrylate brushes from polymeric coatings

Publisher: Elsevier BV

Date: 10-2013

DOI: 10.1016/J.POLYMER.2013.07.077

Slightly Depleted Lubricant-Infused Surfaces Are No Longer Slippery

Publisher: American Chemical Society (ACS)

Date: 16-08-2022

DOI: 10.1021/ACS.LANGMUIR.2C01412

Abstract: Textured surfaces infused with a lubricating fluid effectively reduce fouling and drag. These functions critically depend on the presence and distribution of the lubricant, which can be depleted by many mechanisms, including shear flow. We present a two-phase Couette flow computational dynamic simulation over lubricant-infused surfaces containing grooves oriented perpendicular to the flow direction, with the aim of revealing how interfacial slip, and therefore drag reduction, is impacted by lubricant depletion. We show that even a slight (20%) lubricant loss decreases slip to the point of making the lubricant superfluous, even for lubricants with lower viscosity than the flowing liquid and regardless of how well the lubricant wets the grooves. We explain that the drastic slip reduction is linked to a significant increase in the total viscous dissipation and to zero dissipation in the lubricant (similar to the one given by a no-slip boundary).

A new way to prepare nanostructured materials: Flame spraying of microemulsions

Publisher: American Chemical Society (ACS)

Date: 25-05-2002

DOI: 10.1021/JP012098P

Detection of Nanobubbles on Lubricant-Infused Surfaces Using AFM Meniscus Force Measurements

Publisher: American Chemical Society (ACS)

Date: 12-08-2022

DOI: 10.1021/ACS.LANGMUIR.2C01411

Abstract: So far, the presence of nanobubbles on lubricant-infused surfaces (LIS) has been overlooked, because of the difficulty in detecting them in such a complex system. We recently showed that anomalously large interfacial slip measured on LIS is explained by the presence of nanobubbles [Vega-Sánchez, Peppou-Chapman, Zhu and Neto,

Ultra-thin patchy polymer-coated graphene oxide as a novel anticancer drug carrier

Publisher: Royal Society of Chemistry (RSC)

Date: 2021

DOI: 10.1039/D0PY00769B

Abstract: PISA generated polymer pimples on single graphene oxide sheets maintain colloidal stability for the adsorption and release of DOX.

Reconciling Slip Measurements in Symmetric and Asymmetric Systems

Publisher: American Chemical Society (ACS)

Date: 11-05-2012

DOI: 10.1021/LA301040D

Abstract: In the past decade, the slip of simple liquids on solid surfaces has been demonstrated by many groups. However, the slip of liquids on wettable surfaces is heavily debated. Using colloid probe atomic force microscopy (AFM), we found the slip length of di-n-octylphthalate in a symmetric wettable system (silica) to be around 11 nm, which raises the question of what the measured slip length in an asymmetric hydrophilic-hydrophobic system would be. To answer this question, we investigated liquid slip in one symmetric nonwettable system (hydrophobic DCDMS or OTS) and in one asymmetric hydrophilic (silica)-hydrophobic (DCDMS) system by the same method at driving velocities of between 10 and 80 μm/s. The slip results obtained from the three systems are in agreement with each other, and this comparison provides a means to self-assess the accuracy and reproducibility of the measured force curves and the fitted slip length in our systems. Furthermore, this method provides access to reliable values of the actual slip length on any investigated flat surface in an asymmetric system, avoiding the difficulty of preparing a symmetric probe/flat surface system in a colloid probe AFM force measurement.

Tunable Nanopatterns via the Constrained Dewetting of Polymer Brushes

Publisher: American Chemical Society (ACS)

Date: 29-07-2013

DOI: 10.1021/MA400593Z

Chain Collapse and Interfacial Slip of Polystyrene Films in Good/Nonsolvent Vapor Mixtures

Publisher: American Chemical Society (ACS)

Date: 08-02-2016

DOI: 10.1021/ACS.MACROMOL.5B02253

Interfacial slip on rough, patterned and soft surfaces: A review of experiments and simulations

Publisher: Elsevier BV

Date: 08-2014

DOI: 10.1016/J.CIS.2014.02.015

Abstract: Advancements in the fabrication of microfluidic and nanofluidic devices and the study of liquids in confined geometries rely on understanding the boundary conditions for the flow of liquids at solid surfaces. Over the past ten years, a large number of research groups have turned to investigating flow boundary conditions, and the occurrence of interfacial slip has become increasingly well-accepted and understood. While the dependence of slip on surface wettability is fairly well understood, the effect of other surface modifications that affect surface roughness, structure and compliance, on interfacial slip is still under intense investigation. In this paper we review investigations published in the past ten years on boundary conditions for flow on complex surfaces, by which we mean rough and structured surfaces, surfaces decorated with chemical patterns, grafted with polymer layers, with adsorbed nanobubbles, and superhydrophobic surfaces. The review is ided in two interconnected parts, the first dedicated to physical experiments and the second to computational experiments on interfacial slip of simple (Newtonian) liquids on these complex surfaces. Our work is intended as an entry-level review for researchers moving into the field of interfacial slip, and as an indication of outstanding problems that need to be addressed for the field to reach full maturity.

Interplay between Dewetting and Layer Inversion in Poly(4-vinylpyridine)/Polystyrene Bilayers

Publisher: American Chemical Society (ACS)

Date: 21-09-2010

DOI: 10.1021/LA103078K

Abstract: We investigated the morphology and dynamics of the dewetting of metastable poly(4-vinylpyridine) (P4VP) thin films situated on top of polystyrene (PS) thin films as a function of the molecular weight and thickness of both films. We focused on the competition between the dewetting process, occurring as a result of unfavorable intermolecular interactions at the P4VP/PS interface, and layer inversion due to the lower surface energy of PS. By means of optical and atomic force microscopy (AFM), we observed how both the dynamics of the instability and the morphology of the emerging patterns depend on the ratio of the molecular weights of the polymer films. When the bottom PS layer was less viscous than the top P4VP layer (liquid-liquid dewetting), nucleated holes in the P4VP film typically stopped growing at long annealing times because of a combination of viscous dissipation in the bottom layer and partial layer inversion. Full layer inversion was achieved when the viscosity of the top P4VP layer was significantly greater (>10⁴) than the viscosity of the PS layer underneath, which is attributed to strongly different mobilities of the two layers. The density of holes produced by nucleation dewetting was observed for the first time to depend on the thickness of the top film as well as the polymer molecular weight. The final (completely dewetted) morphology of isolated droplets could be achieved only if the time frame of layer inversion was significantly slower than that of dewetting, which was characteristic of high-viscosity PS underlayers that allowed dewetting to fall into a liquid-solid regime. Assuming a simple reptation model for layer inversion occurring at the dewetting front, the observed surface morphologies could be predicted on the basis of the relative rates of dewetting and layer inversion.

Correlated dewetting patterns in thin polystyrene films

Publisher: IOP Publishing

Date: 13-12-2003

DOI: 10.1088/0953-8984/15/1/358

A review on the mechanical and thermodynamic robustness of superhydrophobic surfaces

Publisher: Elsevier BV

Date: 08-2017

DOI: 10.1016/J.CIS.2017.05.018

Abstract: Advancements in the fabrication and study of superhydrophobic surfaces have been significant over the past 10years, and some 20years after the discovery of the lotus effect, the study of special wettability surfaces can be considered mainstream. While the fabrication of superhydrophobic surfaces is well advanced and the physical properties of superhydrophobic surfaces well-understood, the robustness of these surfaces, both in terms of mechanical and thermodynamic properties, are only recently getting attention in the literature. In this review we cover publications that appeared over the past ten years on the thermodynamic and mechanical robustness of superhydrophobic surfaces, by which we mean the long term stability under conditions of wear, shear and pressure. The review is ided into two parts, the first dedicated to thermodynamic robustness and the second dedicated to mechanical robustness of these complex surfaces. Our work is intended as an introductory review for researchers interested in addressing longevity and stability of superhydrophobic surfaces, and provides an outlook on outstanding aspects of investigation.

Processing waveguide photonic components into self-assembled organic films

Publisher: IEEE

Date: 07-2009

DOI: 10.1109/OECC.2009.5215355

Uptake of water droplets by non-wetting capillaries

Publisher: Royal Society of Chemistry (RSC)

Date: 2011

DOI: 10.1039/C0SM00574F

Waterborne, all-polymeric, colloidal 'raspberry' particles with controllable hydrophobicity and water droplet adhesion properties

Publisher: Elsevier BV

Date: 03-2016

DOI: 10.1016/J.TSF.2016.01.052

Nanobubbles explain the large slip observed on lubricant-infused surfaces

Publisher: Springer Science and Business Media LLC

Date: 17-01-2022

DOI: 10.1038/S41467-022-28016-1

Abstract: Lubricant-infused surfaces hold promise to reduce the huge frictional drag that slows down the flow of fluids at microscales. We show that infused Teflon wrinkled surfaces induce an effective slip length 50 times larger than expected based on the presence of the lubricant alone. This effect is particularly striking as it occurs even when the infused lubricant’s viscosity is several times higher than that of the flowing liquid. Crucially, the slip length increases with increasing air content in the water but is much higher than expected even in degassed and plain Milli-Q water. Imaging directly the immersed interface using a mapping technique based on atomic force microscopy meniscus force measurements reveals that the mechanism responsible for this huge slip is the nucleation of surface nanobubbles. Using a numerical model and the height and distribution of these surface nanobubbles, we can quantitatively explain the large fluid slip observed in these surfaces.

Evidence of shear-dependent boundary slip in newtonian liquids

Publisher: Springer Science and Business Media LLC

Date: 11-2003

DOI: 10.1140/EPJED/E2003-01-018-0

Abstract: The flow of Newtonian fluids was studied by directly measuring the hydrodynamic drainage force acting on a sphere approaching a flat surface. Our force measurements provide clear evidence of boundary slip and show that the degree of boundary slip is a function of the liquid viscosity and the shear rate. A shear-dependent boundary slippage was also observed in experiments with a polymer (PDMS). The liquids wetted the bounding surfaces either partially or completely. Our results have important consequences for the design of microfluidic devices, and in technological processes, such as lubrication and permeability of microporous media.

Cassie’s Law Reformulated: Composite Surfaces from Superspreading to Superhydrophobic

Publisher: American Chemical Society (ACS)

Date: 24-07-2023

DOI: 10.1021/ACS.LANGMUIR.3C01313

Ordered microphase separation in thin films of pmma-pba synthesized by RAFT: Effect of block polydispersity

Publisher: American Chemical Society (ACS)

Date: 26-03-2009

DOI: 10.1021/MA9004428

Reliable Measurements of Interfacial Slip by Colloid Probe Atomic Force Microscopy. III. Shear-Rate-Dependent Slip

Publisher: American Chemical Society (ACS)

Date: 08-02-2012

DOI: 10.1021/LA204566H

Abstract: We present experimental evidence and theoretical models that demonstrate that the slip length, which is the departure from the hydrodynamic no-slip boundary condition, cannot be constant as commonly assumed, but must decrease with increasing shear rate to avoid an unphysical ergence in the velocity of the fluid adjacent to the surface at small separations. The molecular origin of the shear rate dependence of the slip length is discussed. A new theoretical model for slip (the saturation model) is obtained, and it is shown to describe accurately colloid probe atomic force microscopy force measurements for all separations down to a few nanometers in two partially wetting situations (di-n-octyl phthalate on silanized silicon and bare silicon). Previous observations of slip length increasing with shear rate are explained as due to an imprecise calculation of the drag force on the cantilever. A new way of plotting experimental data is also presented, which provides a useful way to illustrate the slip length dependence on the shear rate.

Marine Antifouling Behavior of Lubricant-Infused Nanowrinkled Polymeric Surfaces

Publisher: American Chemical Society (ACS)

Date: 16-01-2018

DOI: 10.1021/ACSAMI.7B14736

Abstract: A new family of polymeric, lubricant-infused, nanostructured wrinkled surfaces was designed that effectively retains inert nontoxic silicone oil, after draining by spin-coating and vigorous shear for 2 weeks. The wrinkled surfaces were fabricated using three different polymers (Teflon AF, polystyrene, and poly(4-vinylpyridine)) and two shrinkable substrates (Polyshrink and shrinkwrap), and Teflon on Polyshrink was found to be the most effective system. The volume of trapped lubricant was quantified by adding Nile red to the silicone oil before infusion and then extracting the oil and Nile red from the surfaces in heptane and measuring by fluorimetry. Higher volumes of lubricant induced lower roll-off angles for water droplets, and in turn induced better antifouling performance. The infused surfaces displayed stability in seawater and inhibited growth of Pseudoalteromonas spp. bacteria up to 99%, with as little as 0.9 μL cm

Colloid probe characterization: Radius and roughness determination

Publisher: American Chemical Society (ACS)

Date: 28-02-2001

DOI: 10.1021/LA001506Y

Micropatterned substrates made by polymer bilayer dewetting and collagen nanoscale assembly support endothelial cell adhesion

Publisher: Royal Society of Chemistry (RSC)

Date: 2012

DOI: 10.1039/C2SM26557E

An experimental study of interactions between droplets and a nonwetting microfluidic capillary

Publisher: Royal Society of Chemistry (RSC)

Date: 2010

DOI: 10.1039/B925588E

Abstract: We present a detailed experimental study of water drops coming into contact with the end of vertical polytetrafluoroethane (PTFE) capillary tubes. The drops, supported on a superhydrophobic substrate, were between 0.06 and 1.97 mm in radius, and the inner radius of the vertical tube was 0.15 mm. These experiments expand on our recent work, which demonstrated that small water droplets can spontaneously penetrate non-wetting capillaries, driven by the action of Laplace pressure within the droplet, and that the dynamics of microfluidic capillary uptake are strongly dependent on the size of the incident drop. Here we quantitatively bound the critical drop radius at which droplets can penetrate a pre-filled capillary to the narrow range between 0.43 and 0.50 mm. This value is consistent with a water-PTFE contact angle between 107.8 degrees and 110.6 degrees. Capillary uptake dynamics were not significantly affected by the initial filling height, but other experimental factors have been identified as important to the dynamics of this process. In particular, interactions between the droplet, the substrate and the tubing are unavoidable prior to and during droplet uptake in a real microfluidic system. Such interactions are classified and discussed for the experimental set-up used, and the difficulties and requirements for droplet penetration of a dry capillary are outlined. These results are relevant to research into microfluidic devices, inkjet printing, and the penetration of fluids in porous materials.

Self-assembly of magnetic nanoparticles into complex superstructures: Spokes and spirals

Publisher: Elsevier BV

Date: 11-2005

DOI: 10.1016/J.COLSURFA.2005.06.072

Mechanical properties of Ropaque hollow nanoparticles

Publisher: Elsevier BV

Date: 11-2017

DOI: 10.1016/J.POLYMER.2017.10.030

Satellite hole formation during dewetting: Experiment and simulation

Publisher: IOP Publishing

Date: 07-05-2003

DOI: 10.1088/0953-8984/15/19/334

Advances and challenges in slippery covalently-attached liquid surfaces

Publisher: Elsevier BV

Date: 05-2023

DOI: 10.1016/J.CIS.2023.102906

Focused ion beam processing and engineering of devices in self-assembled supramolecular structures

Publisher: IOP Publishing

Date: 30-10-2009

DOI: 10.1088/0957-4484/20/48/485301

Abstract: Self-assembled supramolecular structures such as optical wires, films and 2D slabs offer a new generation of electronic and optical devices. In particular, self-assembled porphyrin devices, including those integrated onto silica and silicon platforms, open new opportunities in photonic applications spanning molecular biosensing, photovoltaics and telecommunications. All reports to date, however, largely highlight the potential but have not established a clear pathway to the actual implementation of more complex device prototypes. In this paper, we propose and demonstrate the use of a focused ion beam (FIB) to process and fabricate devices in porphyrin-based supramolecular structures. These self-assembled structures have an initial root mean squared (rms) values for surface roughness of < 0.5 nm as measured by atomic force microscopy. Under appropriate FIB processing and cutting conditions, the rms value for surface roughness falls to < 0.4 nm, comparable with some of the best optical flatnesses obtained within, for ex le, structured optical fibres and integrated optical waveguides. The milling rate of the porphyrin structures was estimated to be approximately 70% of that of silica. The versatility of a FIB as a tool for rapid processing and fabricating 1D and 2D photonic waveguide structures within supramolecular self-assembled platforms is demonstrated by fabricating a 2D coupler, setting the groundwork for true optical device engineering and integration using these new organic systems.

Dynamics and structure formation in thin polymer melt films

Publisher: IOP Publishing

Date: 19-02-2005

DOI: 10.1088/0953-8984/17/9/001

Biomimetic surface coatings for atmospheric water capture prepared by dewetting of polymer films

Publisher: Wiley

Date: 15-07-2011

DOI: 10.1002/ADMA.201100290

Nanostructure Explains the Behavior of Slippery Covalently Attached Liquid Surfaces

Publisher: Wiley

Date: 04-09-2023

DOI: 10.1002/ANGE.202308008

Abstract: Slippery covalently‐attached liquid surfaces (SCALS) with low contact angle hysteresis (CAH, ◦) and nanoscale thickness display impressive anti‐adhesive properties, similar to lubricant‐infused surfaces. Their efficacy is generally attributed to the liquid‐like mobility of the constituent tethered chains. However, the precise physico‐chemical properties that facilitate this mobility are unknown, hindering rational design. This work quantifies the chain length, grafting density, and microviscosity of a range of polydimethylsiloxane (PDMS) SCALS, elucidating the nanostructure responsible for their properties. Three prominent methods are used to produce SCALS, with characterization carried out via single‐molecule force measurements, neutron reflectometry, and fluorescence correlation spectroscopy. CO2 snow‐jet cleaning was also shown to reduce the CAH of SCALS via a modification of their grafting density. SCALS behavior can be predicted by reduced grafting density, Σ, with the lowest water CAH achieved at Σ ≈ 2. This study provides the first direct examination of SCALS grafting density, chain length, and microviscosity and supports the hypothesis that SCALS properties stem from a balance of layer uniformity and mobility.

Boundary slip in Newtonian liquids: a review of experimental studies

Publisher: IOP Publishing

Date: 10-10-2005

DOI: 10.1088/0034-4885/68/12/R05

Depletion of the Lubricant from Lubricant-Infused Surfaces due to an Air/Water Interface

Publisher: American Chemical Society (ACS)

Date: 08-03-2021

DOI: 10.1021/ACS.LANGMUIR.0C02858

Control of nanoparticle formation using the constrained dewetting of polymer brushes

Publisher: Royal Society of Chemistry (RSC)

Date: 2015

DOI: 10.1039/C4NR07412B

Abstract: We propose a method for the preparation of functional surface nanoparticle arrays using the self-assembly of polymer brushes.

On the superhydrophobic properties of nickel nanocarpets

Publisher: Royal Society of Chemistry (RSC)

Date: 2009

DOI: 10.1039/B909899B

Abstract: A surface formed by dense, aligned nickel nanowires (a "nanocarpet") was prepared by electrodeposition through an alumina membrane template, followed by dissolution of the membrane. The nickel nanowires forming the nanocarpet have a very high aspect ratio ( approximately 250), with a diameter of 200 nm and a length of several tens of micrometers. The nickel nanowires are highly rigid, perpendicularly aligned in the nanocarpet with respect to the substrate, and they touch each other at the tips, forming microscale "tepee"-shaped aggregates. By comparison, nanocarpets made of platinum nanowires have a more disordered, wave-like appearance. The nickel nanocarpet, once coated with a hydrophobic surfactant (stearic acid) has superhydrophobic properties (advancing contact angle approximately 158 degrees), and retains its superhydrophobicity after periods of immersion in water, similar to the hydrophobised platinum nanocarpet (advancing contact angle approximately 162 degrees). Interestingly, we observe that simple electrodeposition of platinum also produces pronounced superhydrophobic properties on "flat" copper surfaces. The magnetic properties of nickel might widen the range of applications in which nanocarpets can be gainfully used, such as in surfaces of switchable wettability for microfluidic applications.

Micron-sized polystyrene particles by surfactant-free emulsion polymerization in air: Synthesis and mechanism

Publisher: Wiley

Date: 10-07-2013

DOI: 10.1002/POLA.26841

Micropatterning of polymer brushes: Grafting from dewetting polymer films for biological applications

Publisher: American Chemical Society (ACS)

Date: 24-08-2012

DOI: 10.1021/BM3010534

Abstract: In this novel platform, a micropatterned polymer brush was obtained by grafting poly(poly(ethylene glycol) methyl ether methacrylate) (poly(PEGMA)) from a thin macroinitiator film using atom transfer radical polymerization (ATRP). A pattern of holes was formed in the macroinitiator film by taking advantage of its spontaneous dewetting above the glass transition temperature from a bottom polystyrene film, driven by unfavorable intermolecular forces. Patterning by dewetting can be achieved at length-scales from a few hundred nanometers to several tens of micrometers, by simply thermally annealing the bilayer above the glass transition temperature of the polymer. This approach is substrate-independent, as polymer films can be cast onto surfaces of different size, shape, or material. As a demonstration of its potential, proteins, and in idual cells were attached on targeted bioadhesive polystyrene areas of the micropatterns within poly(PEGMA) protein-repellent brushes. We anticipate this approach will be suitable for the patterning of brushes, especially for biomedical applications such as in the study of single cells and of cell cocultures.

Patterned chemisorption of proteins by thin polymer film dewetting

Publisher: Royal Society of Chemistry (RSC)

Date: 2013

DOI: 10.1039/C3SM27241A

Chemical Curiosity on Campus: An Undergraduate Project on the Structure and Wettability of Natural Surfaces

Publisher: American Chemical Society (ACS)

Date: 27-06-2019

DOI: 10.1021/ACS.JCHEMED.9B00324

Supramolecular porphyrin wires and post-processing

Publisher: IEEE

Date: 07-2009

DOI: 10.1109/OECC.2009.5218375

Reliable Measurements of Interfacial Slip by Colloid Probe Atomic Force Microscopy. II. Hydrodynamic Force Measurements

Publisher: No publisher found

Date: 2011

DOI: 10.1021/LA104597D

Abstract: Here we report a new study on the boundary conditions for the flow of a simple liquid in a confined geometry obtained by measuring hydrodynamic drainage forces with colloid probe atomic force microscopy (AFM). In this work, we provide experimental data obtained using a best practice experimental protocol and fitted with a new theoretical calculation (Zhu, L. Attard, P. Neto, C. Langmuir 2010, submitted for publication, preceding paper). We investigated the hydrodynamic forces acting on a silica colloid probe approaching a hydrophobized silicon surface in a single-component viscous Newtonian liquid (di-n-octylphthalate), a partially wetting system. The measured average slip lengths were in the range of 24-31 nm at approach velocities of between 10 and 80 μm/s. Using our experimental approach, the presence of nanoparticle contaminants in the system can be indentified, which is important because it has been shown that nanoparticles lead to a large apparent slip length. Under our stringent control of experimental conditions, the measurement of the slip length is reproducible and independent of the spring constant of the cantilever.

Durable Superhydrophobic Surfaces via Spontaneous Wrinkling of Teflon AF

Publisher: American Chemical Society (ACS)

Date: 04-03-2016

DOI: 10.1021/ACSAMI.5B12165

Abstract: We report the fabrication of both single-scale and hierarchical superhydrophobic surfaces, created by exploiting the spontaneous wrinkling of a rigid Teflon AF film on two types of shrinkable plastic substrates. Sub-100 nm to micrometric wrinkles were reproducibly generated by this simple process, with remarkable control over the size and hierarchy. Hierarchical Teflon AF wrinkled surfaces showed extremely high water repellence (contact angle 172°) and very low contact angle hysteresis (2°), resulting in droplets rolling off the surface at tilt angles lower than 5°. The wrinkling process intimately binds the Teflon AF layer with its substrate, making these surfaces mechanically robust, as revealed by macroscale and nanoscale wear tests: hardness values were close to that of commercial optical lenses and aluminum films, resistance to scratch was comparable to commercial hydrophobic coatings, and damage by extensive sonication did not significantly affect water repellence. By this fabrication method the size of the wrinkles can be reproducibly tuned from the nanoscale to the microscale, across the whole surface in one step the fabrication procedure is extremely rapid, requiring only 2 min of thermal annealing to produce the desired topography, and uses inexpensive materials. The very low roll-off angles achieved in the hierarchical surfaces offer a potentially up-scalable alternative as self-cleaning and drag-reducing coatings.

Colloidal particles of Ca(OH)(2): Properties and applications to restoration of frescoes

Publisher: American Chemical Society (ACS)

Date: 13-06-2001

DOI: 10.1021/LA010269B

Antifouling Properties of Liquid‐Infused Riblets Fabricated by Direct Contactless Microfabrication

Publisher: Wiley

Date: 13-11-2021

DOI: 10.1002/ADEM.202000905

Mapping Depletion of Lubricant Films on Antibiofouling Wrinkled Slippery Surfaces

Publisher: American Chemical Society (ACS)

Date: 31-08-2018

DOI: 10.1021/ACSAMI.8B11768

Abstract: Slippery liquid infused porous surfaces (SLIPS) have recently gained a lot of attention because of their wide range of applications. We recently showed that SLIPS with most of their surface depleted of lubricant, as little lubricant as 0.02 ± 0.01 μL cm

Rapid photochromic nanopatterns from block copolymers

Publisher: Royal Society of Chemistry (RSC)

Date: 2010

DOI: 10.1039/B920133E

On the superhydrophobic properties of crystallized stearic acid

Publisher: CSIRO Publishing

Date: 2010

DOI: 10.1071/CH09292

Abstract: A surface coating formed by stearic acid (SA) crystals was prepared by repeatedly dipping a silicon substrate into a SA solution and drying it in air. Scanning electron microscopy imaging revealed that the surface roughness of the coating increases with each dip-and-dry cycle. The coating appears as a carpet of hydrophobic ‘blades’, and is superhydrophobic (after 20 dipping cycles advancing contact angle ~160°), even after immersion in water for up to 2 h. This simple method could be applied to large areas, making this an interesting alternative to high-tech surface modification techniques.

Early and Intermediate Stages of Guided Dewetting in Polystyrene Thin Films

Publisher: American Chemical Society (ACS)

Date: 26-06-2012

DOI: 10.1021/LA301773H

Abstract: We investigated the early and intermediate stages of the guided dewetting of polystyrene (PS) thin films on chemically patterned silicon, achieved by micro-contact printing of non-wettable self-assembling monolayers of an alkylsilane. Two different types of ordered patterns could be achieved depending on the annealing temperature and time. Study of the dynamics of hole growth revealed a deviation of the growth profile from the trend on homogeneous substrates, attributed to the pinning of the PS rims on the borders of the hydrophobic regions. The ordered patterns produced could be useful in applications that require spatially localized features of controlled surface chemistry, such as studies in proteomics, single cell studies, and biosensors.

Life and death of liquid-infused surfaces: a review on the choice, analysis and fate of the infused liquid layer

Publisher: Royal Society of Chemistry (RSC)

Date: 2020

DOI: 10.1039/D0CS00036A

Abstract: We review the rational choice, the analysis, the depletion and the properties imparted by the liquid layer in liquid-infused surfaces – a new class of low-adhesion surface.

Shear-Dependent Boundary Slip in an Aqueous Newtonian Liquid

Publisher: American Physical Society (APS)

Date: 17-07-2001

DOI: 10.1103/PHYSREVLETT.87.054504

Effect of Pore Size, Lubricant Viscosity, and Distribution on the Slippery Properties of Infused Cement Surfaces

Publisher: American Chemical Society (ACS)

Date: 30-01-2019

DOI: 10.1021/ACS.JPCC.8B11221

Ultralow surface energy self-assembled monolayers of iodo-perfluorinated alkanes on silica driven by halogen bonding

Publisher: Royal Society of Chemistry (RSC)

Date: 2019

DOI: 10.1039/C8NR08195F

Abstract: Self-assembled monolayers of iodo-perfluoro alkanes are shown to form on silica surfaces, guided by halogen bonding.

Quantification of Nucleation Site Density as a Function of Surface Wettability on Smooth Surfaces

Publisher: Wiley

Date: 07-04-2022

DOI: 10.1002/ADMI.202200246

Abstract: Dew water is recognized as a valuable source of clean water for human consumption. Given the developing concerns over global water scarcity, great focus has been turned toward increasing the efficiency of existing dew harvesting methodologies. Droplet nucleation is a critical first stage in the condensation process – and therefore key to dew water harvesting. In this paper, the droplet nucleation site density ( N s ) as a function of surface wettability on smooth thin polymer films is quantified. A custom‐built environment chamber, operated in low supersaturation conditions relevant to atmospheric water harvesting, allows strict experimental control over temperature and humidity. Droplet growth through coalescence is quantified, and an exponential increase in the rate of coalescence is seen as the test surface wettability increased. N s declines exponentially as wettability decreases according to the fitted equation N s = 1.1 × 10 11 e −0.043θ , where theta is the contact angle of the smooth surface, which can be used to predict N s from a known contact angle, currently not available. The average distance between droplet centers is found to increase at a linear rate. This nucleation behavior is in line with those of droplets in a Rayleigh distribution.

The Good, the Bad, and the Slippery: A Tale of Three Solvents in Polymer Film Dewetting

Publisher: American Chemical Society (ACS)

Date: 09-2016

DOI: 10.1021/ACS.MACROMOL.6B01579

Competition between Dewetting and Cross-Linking in Poly(N-vinylpyrrolidone)/Polystyrene Bilayer Films

Publisher: American Chemical Society (ACS)

Date: 09-11-2011

DOI: 10.1021/LA2029577

Abstract: We investigated the dewetting of metastable poly(N-vinylpyrrolidone) (PNVP) thin films (45 nm) on top of polystyrene (PS) thin films (58 nm) as a function of annealing temperature and molecular weight of PS (96 and 6850 kg/mol). We focused on the competition between dewetting, occurring as a result of unfavorable intermolecular interactions at the PNVP/PS interface, and spontaneous cross-linking of PNVP, occurring during thermal annealing, as we recently reported (Telford, A. M. James, M. Meagher, L. Neto, C. ACS Appl. Mater. Interfaces 2010, 2, 2399-2408). Using optical microscopy, we studied how the dewetting morphology and dynamics at different temperatures depended on the relative viscosity of the top PNVP film, which increased with cross-linking time, and of the bottom PS film. In the PNVP/PS96K system, cross-linking dominated over dewetting at temperatures below 180 °C, reducing drastically nucleated hole density and their maximum size, while above 180 °C the two processes reversed, with complete dewetting occurring at 200 °C. On the other hand, the PNVP/PS6850K system never achieved advanced dewetting stages as the dewetting was slower than cross-linking in the investigated temperature range. In both systems, dewetting of the PNVP films could be avoided altogether by thermally annealing the bilayers at temperatures where cross-linking dominated. The cross-linking was characterized quantitatively using neutron reflectometry, which indicated shrinkage and densification of the PNVP film, and qualitatively through selective removal of the bottom PS film. A simple model accounting for progressive cross-linking during the dewetting process predicted well the observed hole growth profiles and produced estimates of the PNVP cross-linking rate coefficients and of the activation energy of the process, in good agreement with literature values for similar systems.

Design Optimization of Perfluorinated Liquid‐Infused Surfaces for Blood‐Contacting Applications

Publisher: Wiley

Date: 29-01-2022

DOI: 10.1002/ADMI.202102214

Abstract: Tethered‐liquid perfluorocarbon (TLP) coatings show promise for blood‐contacting medical device applications to reduce blood adhesion and delay thrombosis. However, their fabrication and longevity under external fluid flow is not well characterized. A vapor phase silanization reaction leading to the formation of tethered‐perfluorocarbon (TP) layers containing large bumpy aggregates, 300 ± 200 nm thick, on top of an underlying 35 ± 15 nm thick uniform coating is reported. The vapor phase method compares favorably to the well‐established liquid phase deposition to reproducibly create slippery coatings on silicon and polystyrene with very low water sliding angles (2° ± 1°), without the need to control humidity conditions. The TP layer retains perfluorinated lubricants up to 20 000 s –1 , using a cone‐and‐plate rheometer, with the higher viscosity lubricant perfluoroperhydrophenanthrene being more resistant to depletion than perfluorodecalin. TLP infused with either of the lubricants effectively reduces adhesion of fibrin from human whole blood relative to TP and control hydrophilic and hydrophobic surfaces. The combination of highly fluorinated TP coatings grafted from the vapor phase to create nanoscale structured surfaces infused with higher viscosity lubricant may be the most suitable combination for clinical applications of liquid‐infused surfaces to reduce thrombosis in blood‐contacting medical devices under flow.

Exploring the water capture efficiency of covalently attached liquid-like surfaces

Publisher: AIP Publishing

Date: 06-06-2023

DOI: 10.1063/5.0146847

Abstract: The capture of moisture from the atmosphere through condensation has the potential to provide a sustainable source of water. Here, we investigate the condensation of humid air at low subcooling condition (11 °C), similar to conditions for natural dew capture, and explore how water contact angle and contact angle hysteresis affect the rates of water capture. We compare water collection on three families of surfaces: (i) hydrophilic (polyethylene oxide, MPEO) and hydrophobic (polydimethylsiloxane, PDMS) molecularly thin coatings grafted on smooth silicon wafers, which produce slippery covalently attached liquid surfaces (SCALSs), with low contact angle hysteresis (CAH = 6°) (ii) the same coatings grafted on rougher glass, with high CAH (20°–25°) (iii) hydrophilic polymer surfaces [poly(N-vinylpyrrolidone), PNVP] with high CAH (30°). Upon exposure to water, the MPEO SCALS swell, which likely further increases their droplet shedding ability. MPEO and PDMS coatings collect similar volume of water (around 5 l m−2 day−1), both when they are SCALS and non-slippery. Both MPEO and PDMS layers collect about 20% more water than PNVP surfaces. We present a basic model showing that, under low heat flux conditions, on all MPEO and PDMS layers, the droplets are so small (600–2000 µm) that there is no/low heat conduction resistance across the droplets, irrespective of the exact value of contact angle and CAH. As the time to first droplet departure is much faster on MPEO SCALS (28 min) than on PDMS SCALS (90 min), slippery hydrophilic surfaces are preferable in dew collection applications where the collection time frame is limited.

Large Effective Slip on Lubricated Surfaces Measured with Colloidal Probe AFM

Publisher: American Chemical Society (ACS)

Date: 20-05-2020

DOI: 10.1021/ACS.LANGMUIR.9B02935

Pressure Drop Measurements in Microfluidic Devices: A Review on the Accurate Quantification of Interfacial Slip

Publisher: Wiley

Date: 13-12-2022

DOI: 10.1002/ADMI.202101641

Abstract: The correct theoretical definition of boundary conditions of flow underpins all fluid dynamics studies, and is particularly important in situations in which the flow is confined on the nano‐ and micro‐scale. Microfluidic devices are an excellent platform to measure boundary flow conditions, and the pressure drop versus flow rate method is particularly useful in detecting evidence of microscale interfacial slip and drag reduction. This review focuses on the pressure drop method, identifying the main experimental parameters affecting the accuracy and reproducibility of microfluidic experiments of slip, quantifying the magnitude and source of common errors, and providing practical solutions and guidelines. A summary of literature results of interfacial slip obtained with pressure drop measurements in microfluidic devices is also provided, and the slip results are directly compared to expected slip models. This review serves as an introduction for new researchers moving into the field of interfacial slip, and as reminder for established researchers of the need to create highly controlled experimental procedures in order to obtain reproducible and reliable measurements of boundary flow conditions. A direct comparison of accurate experiments with theoretical models is bound to bring about clarity about the mechanisms of slip on smooth and structured surfaces.

Long self-assembled organic molecular optical wires

Publisher: IEEE

Date: 11-2008

DOI: 10.1109/LEOS.2008.4688686

Receding Contact Line Motion on Nanopatterned and Micropatterned Polymer Surfaces

Publisher: American Chemical Society (ACS)

Date: 24-10-2017

DOI: 10.1021/ACS.LANGMUIR.7B03100

Abstract: Surface properties such as topography and chemistry affect the motion of the three-phase contact line (solid/liquid/air), which in turn affects the contact angle of a liquid moving on a solid surface. In this work, the motion of the receding water contact line was studied on chemically and topographically patterned surfaces obtained from the dewetting of thin polymer films. The patterned surfaces consisted of hydrophilic poly(4-vinylpyridine) (P4VP) bumps, which were either microsized and sparse or nanosized and dense, on top of a hydrophobic polystyrene (PS) background layer. These patterns are designed for atmospheric water capture, for which the easy roll off of water droplets is crucial to their efficient performance. The dynamic receding water contact angle and contact line height of the patterned surfaces were measured by vertically withdrawing the surfaces from a water bath and compared to those of a flat P4VP substrate. For both the micropatterned and nanopatterned surfaces, the height of the dynamic contact lines normalized by the capillary length was characterized by the equilibrium limit that was predicted from static states. The nanopatterned surface had a faster increase in the normalized height as the capillary number increased. The dynamic receding contact angles on all surfaces studied decreased with increasing withdrawing velocity. Surprisingly, even for these patterned surfaces with high hysteresis, the dynamic receding contact angle followed the Cox-Voinov relation at capillary numbers of between 1 × 10

Novel fibrinogen mutation γ314Thr→Pro (fibrinogen AI duPont) associated with hepatic fibrinogen storage disease and hypofibrinogenaemia

Publisher: Wiley

Date: 23-07-2010

DOI: 10.1111/J.1478-3231.2010.02312.X

Abstract: Mutation in fibrinogen genes may lead to quantitative or qualitative disorders that result in bleeding, thrombosis or hepatic fibrinogen storage disease. Only three mutations in the fibrinogen γ gene have been identified that cause hepatic endoplasmic reticulum storage of mutant fibrinogen. To investigate the possibility of hepatic fibrinogen storage disease in a 4-year-old male with persistently elevated serum aminotransferases and preserved synthetic function except for a prolonged INR. After informed consent, liver and blood s les were obtained. Liver sections were examined by light microscopy, anti-fibrinogen immunolabelling and electron microscopy. Purified fibrinogen was analysed by sodium dodecyl sulphate-polyacrylamide gel electrophoresis and reverse phase high performance liquid chromatography DNA sequencing was performed using a BigDye Terminator (v. 3.1) cycle sequencing kit. Four-year-old male with persistently elevated transaminases with an INR 1.5 but otherwise normal synthetic function. Fibrinogen activity and thrombin clotting time were abnormal at 0.47 g/L and 46 s respectively. Hepatic histological examination revealed portal inflammatory infiltrates with bridging fibrosis. Clumped eosinophilic material was observed in hepatocytes that was immunoreactive to fibrinogen antisera. Ultrastructural examination showed cytoplasmic inclusions arrayed in fingerprint-like patterns. DNA sequence analysis revealed heterozygosity for a novel γ314Thr →Pro mutation (fibrinogen AI duPont) in the fibrinogen γ gene. Protein analyses showed normal patterns of Aα, Bβ and γ chains suggesting that the variant γ allele was not expressed in plasma fibrinogen. We describe only the fourth mutation to be identified, γ314Thr→Pro (fibrinogen AI duPont), giving rise to hypofibrinogenaemia and hepatic fibrinogen storage disease.

Halogen-bond driven self-assembly of perfluorocarbon monolayers on silicon nitride

Publisher: Royal Society of Chemistry (RSC)

Date: 2019

DOI: 10.1039/C9TA04620H

Abstract: We demonstrate that self-assembled monolayers of reproducible thickness can be formed on silicon nitride, driven by halogen bonding using iodo-perfluorinated molecules.

Micropatterned Surfaces for Atmospheric Water Condensation via Controlled Radical Polymerization and Thin Film Dewetting

Publisher: American Chemical Society (ACS)

Date: 21-09-2015

DOI: 10.1021/ACSAMI.5B06856

Abstract: Inspired by an ex le found in nature, the design of patterned surfaces with chemical and topographical contrast for the collection of water from the atmosphere has been of intense interest in recent years. Herein we report the synthesis of such materials via a combination of macromolecular design and polymer thin film dewetting to yield surfaces consisting of raised hydrophilic bumps on a hydrophobic background. RAFT polymerization was used to synthesize poly(2-hydroxypropyl methacrylate) (PHPMA) of targeted molecular weight and low dispersity spin-coating of PHPMA onto polystyrene films produced stable polymer bilayers under appropriate conditions. Thermal annealing of these bilayers above the glass transition temperature of the PHPMA layer led to complete dewetting of the top layer and the formation of isolated PHPMA domains atop the PS film. Due to the vastly different rates of water nucleation on the two phases, preferential dropwise nucleation of water occurred on the PHPMA domains, as demonstrated by optical microscopy. The simplicity of the preparation method and ability to target polymers of specific molecular weight demonstrate the value of these materials with respect to large-scale water collection devices or other materials science applications where patterning is required.

How Slippery are SLIPS? Measuring Effective Slip on Lubricated Surfaces with Colloidal Probe Atmoc Force Microscopy

Publisher: American Chemical Society (ACS)

Date: 05-02-2019

DOI: 10.1021/ACS.LANGMUIR.8B03767

Abstract: Lubricant-infused surfaces have attracted great attention recently and are described as slippery liquid-infused porous surfaces (SLIPS). Here, we measured the hydrodynamic drainage forces on SLIPS by colloid probe atomic force microscopy (AFM) and quantified the effective slip length over a nanothin silicone oil layer on hydrophobized [octadecyltrichlorosilane (OTS)-coated] silicon wafers. The thickness of a stable silicone oil film on OTS-Si under sucrose solution was determined to be 1.8 ± 1.3 nm and was found to induce an average effective slip length of 29 ± 3 nm, very close to that of an uninfused OTS substrate. These relatively low values of effective slip are confirmed by the relatively large macroscopic roll-off angle values of water droplets on the same substrates. Both nano- and macroscale results reflect the immobilized nature of a silicone oil layer of thickness around 2 nm within an underlying monolayer. These results have important implications in the design of drag-reducing coatings using lubricant infusion.

Premature detonation of an NH4NO3 emulsion in reactive ground

Publisher: Elsevier BV

Date: 02-2015

DOI: 10.1016/J.JHAZMAT.2014.08.070

Abstract: When NH4NO3 emulsions are used in blast holes containing pyrite, they can exothermally react with pyrite, causing the emulsion to intensively heat and detonate prematurely. Such premature detonations can inflict fatal and very costly damages. The mechanism of heating of the emulsions is not well understood though such an understanding is essential for designing safe blasting. In this study the heating of an emulsion in model blast holes was simulated by solving the heat equation. The physical factors contributing to the heating phenomenon were studied using microscopic and calorimetric methods. Microscopic studies revealed the continuous formation of a large number of gas bubbles as the reaction progressed at the emulsion-pyrite interface, which made the reacting emulsion porous. Calculations show that the increase in porosity causes the thermal conductivity of a reacting region of an emulsion column in a blast hole to decrease exponentially. This large reduction in the thermal conductivity retards heat dissipation from the reacting region causing its temperature to rise. The rise in temperature accelerates the exothermic reaction producing more heat. Simulations predict a migration of the hottest spot of the emulsion column, which could dangerously heat the primers and boosters located in the blast hole.

Mechanisms for Reduced Fibrin Clot Formation on Liquid‐Infused Surfaces

Publisher: Wiley

Date: 09-09-2022

DOI: 10.1002/ADHM.202201360

Abstract: Biomedical devices are prone to blood clot formation (thrombosis), and liquid‐infused surfaces (LIS) are effective in reducing the thrombotic response. However, the mechanisms that underpin this performance, and in particular the role of the lubricant, are not well understood. In this work, it is investigated whether the mechanism of LIS action is related to i) inhibition of factor XII (FXII) activation and the contact pathway ii) reduced fibrin density of clots formed on surfaces iii) increased mobility of proteins or cells on the surface due to the interfacial flow of the lubricant. The chosen LIS is covalently tethered, nanostructured layers of perfluorocarbons, infused with thin films of medical‐grade perfluorodecalin (tethered‐liquid perfluorocarbon), prepared with chemical vapor deposition previously optimized to retain lubricant under flow. Results show that in the absence of external flow, interfacial mobility is inherently higher at the liquid–blood interface, making it a key contributor to the low thrombogenicity of LIS, as FXII activity and fibrin density are equivalent at the interface. The findings of this study advance the understanding of the anti‐thrombotic behavior of LIS‐coated biomedical devices for future coating design. More broadly, enhanced interfacial mobility may be an important, underexplored mechanism for the anti‐fouling behavior of surface coatings.

A novel approach to the micropatterning of proteins using dewetting of polymer bilayers

Publisher: Royal Society of Chemistry (RSC)

Date: 2007

DOI: 10.1039/B614085H

Abstract: The ability to control protein and cell positioning on a microscopic scale is crucial in many biomedical and bioengineering applications, such as tissue engineering and the development of biosensors. We propose here a novel, simple, and versatile method for the micropatterning of proteins. Micropatterned substrates are produced by the dewetting of a metastable polymer film on top of another polymer film. Selective adsorption, or micropatterning, of proteins can be achieved on such substrates by choosing pairs of polymers which differ in protein affinity. In this study, patterns were produced in bilayers of poly(methylmethacrylate) (PMMA) and polystyrene (PS), and of PMMA and octadecyltrichlorosilane (OTS). Fluorescence microscopy and atomic force microscopy (AFM) provide evidence that model proteins adsorb preferentially on isolated bio-adhesive (PS and OTS) micropatches in a protein-resistant (PMMA) matrix. "Inverse" protein patterns, containing non-adhesive (PMMA) islands in a protein-adhesive (PS) matrix can also be produced. Such micropatterned substrates could potentially be used in the development of biosensors and bioassays, and in the study of cell growth and motility.

Guiding the Dewetting of Thin Polymer Films by Colloidal Imprinting

Publisher: Wiley

Date: 21-04-2015

DOI: 10.1002/ADMI.201500068

Morphological characterization of H aggregates in Langmuir-Blodgett films of pyridinium-dicyanomethanide dyes

Publisher: American Chemical Society (ACS)

Date: 27-02-1999

DOI: 10.1021/LA981364W

Influence of long-range forces and capillarity on the function of underwater superoleophobic wrinkled surfaces

Publisher: Royal Society of Chemistry (RSC)

Date: 2018

DOI: 10.1039/C8SM00709H

Abstract: The forces that stabilise a thin water film in a structured surface are described, forming the basis for underwater superoleophobic behaviour.

Laboratorio De Economia E Modelagem Aplicada

Location: Brazil

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University Of Florence, Italy

Location: Italy

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University Of Sydney

Location: Australia

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Polymer Micro-capsules For Stain-resistant Paint

Start Date: 2018

End Date: 2020

Funder: Australian Research Council

Janus Particles And Nanorattles: New Materials For Paint Technology

Start Date: 2011

End Date: 2013

Funder: Australian Research Council

Gas-enriched Slippery Surfaces

Start Date: 2023

End Date: 2026

Funder: Australian Research Council

Biomimetic Surface Coatings For Drag And Fouling Reduction

Start Date: 2018

End Date: 2021

Funder: Australian Research Council

Micropatterned Polymer Film Coatings For The Capture Of Water Directly From The Atmosphere

Start Date: 2013

End Date: 2016

Funder: Australian Research Council

Inhibition Of Spontaneous Detonations Of Explosive Emulsions In Hot And Reactive Grounds

Start Date: 2010

End Date: 2012

Funder: Australian Research Council

Australian Rheo-Scattering Facilities

Start Date: 2020

End Date: 2020

Funder: Australian Research Council

New Surfaces For The Control Of Endothelial Cell Function: Application In The Design Of Biocompatible Stents

Start Date: 2010

End Date: 2012

Funder: Australian Research Council

Nanorheology: Hydrodynamic Slip In Newtonian Fluids

Start Date: 2003

End Date: 2005

Funder: Australian Research Council

Key Functional Additives In Paint Technology

Start Date: 2014

End Date: 2017

Funder: Australian Research Council

Dynamics At Interfaces: A Facility For The Characterisation Of The Dynamics Of Structural Reorganisation And Adsorption At Interfaces

Start Date: 2005

End Date: 2005

Funder: Australian Research Council

Tailoring Surface Properties To Maximise Boundary Slip For Microfluidic Applications

Start Date: 2011

End Date: 2013

Funder: Australian Research Council

A Unique Soft Matter High-performance Scanning Probe Microscopy (HP-SPM) Facility

Start Date: 2010

End Date: 2010

Funder: Australian Research Council

An X-ray Scattering Facility For Bulk And Interfacial Nanostructure

Start Date: 2017

End Date: 2017

Funder: Australian Research Council

Discovery Projects - Grant ID: DP230100555

Start Date: 04-2023

End Date: 04-2026

Amount: $432,307.00

Funder: Australian Research Council

Discovery Projects - Grant ID: DP110101533

Start Date: 03-2011

End Date: 11-2014

Amount: $250,000.00

Funder: Australian Research Council

Discovery Projects - Grant ID: DP1094768

Start Date: 08-2010

End Date: 09-2013

Amount: $270,000.00

Funder: Australian Research Council

Linkage Projects - Grant ID: LP100100720

Start Date: 10-2010

End Date: 12-2013

Amount: $420,000.00

Funder: Australian Research Council

Linkage Projects - Grant ID: LP130100088

Start Date: 05-2014

End Date: 12-2014

Amount: $325,000.00

Funder: Australian Research Council

Linkage Projects - Grant ID: LP200200806

Start Date: 10-2021

End Date: 10-2024

Amount: $471,900.00

Funder: Australian Research Council

ARC Future Fellowships - Grant ID: FT180100214

Start Date: 02-2019

End Date: 02-2023

Amount: $858,125.00

Funder: Australian Research Council

Linkage Projects - Grant ID: LP110100109

Start Date: 05-2011

End Date: 12-2013

Amount: $480,000.00

Funder: Australian Research Council

Linkage Projects - Grant ID: LP170100090

Start Date: 2018

End Date: 12-2020

Amount: $660,683.00

Funder: Australian Research Council

Linkage Infrastructure, Equipment And Facilities - Grant ID: LE0560758

Start Date: 2005

End Date: 12-2007

Amount: $187,000.00

Funder: Australian Research Council

Linkage Infrastructure, Equipment And Facilities - Grant ID: LE220100114

Start Date: 07-2022

End Date: 12-2023

Amount: $1,040,375.00

Funder: Australian Research Council

Linkage Infrastructure, Equipment And Facilities - Grant ID: LE200100221

Start Date: 02-2021

End Date: 02-2022

Amount: $320,000.00

Funder: Australian Research Council

Linkage Projects - Grant ID: LP140100285

Start Date: 07-2014

End Date: 11-2017

Amount: $480,000.00

Funder: Australian Research Council

Linkage Infrastructure, Equipment And Facilities - Grant ID: LE170100148

Start Date: 2017

End Date: 12-2018

Amount: $300,000.00

Funder: Australian Research Council

Linkage Infrastructure, Equipment And Facilities - Grant ID: LE100100096

Start Date: 2010

End Date: 06-2011

Amount: $450,000.00

Funder: Australian Research Council

Discovery Projects - Grant ID: DP0343788

Start Date: 10-2003

End Date: 12-2007

Amount: $291,000.00

Funder: Australian Research Council