A5075247944- Surfactants and Colloidal Systems
- Advanced Polymer Synthesis and Characterization
- Material Dynamics and Properties
- Polymer Surface Interaction Studies
- Polymer Nanocomposites and Properties
- Fluid Dynamics and Thin Films
- Material Properties and Processing
- Nanomaterials and Printing Technologies
- Conducting polymers and applications
- Pickering emulsions and particle stabilization
- Silicone and Siloxane Chemistry
- Surface Modification and Superhydrophobicity
- Polymer composites and self-healing
- Analytical Chemistry and Sensors
- Carbon Nanotubes in Composites
- Polymer crystallization and properties
- Liquid Crystal Research Advancements
- Phase Equilibria and Thermodynamics
- Rheology and Fluid Dynamics Studies
- NMR spectroscopy and applications
- Photopolymerization techniques and applications
- Spectroscopy and Quantum Chemical Studies
- Force Microscopy Techniques and Applications
- biodegradable polymer synthesis and properties
- Photonic Crystals and Applications
University of Surrey
2015-2024
Guildford Hospital
2017-2019
École d'Ingénieurs en Chimie et Sciences du Numérique
2016
Centre National de la Recherche Scientifique
2016
Université Claude Bernard Lyon 1
2016
South East Physics Network
2012
University of the Basque Country
2003-2010
National Academy of Sciences of Belarus
2009
B.I. Stepanov Institute of Physics
2009
Clausthal University of Technology
2008
The glass transition temperature of thin polystyrene films has been measured as a function film thickness. It is found that the decreases in thickness reduced. effect not strongly molecular-weight dependent, ruling out chain confinement major cause; instead we suggest at surface glassy liquidlike layer exists whose size diverges approached from below.
We have measured the thickness dependence of glass-transition temperature (Tg) thin films poly(methyl methacrylate)(PMMA) by using spectroscopic ellipsometry to detect discontinuity in thermal expansivity occurring at Tg. studied on two surfaces: native oxide silicon, and evaporated gold. The Tg PMMA a gold surface decreases with decreasing film thickness, accordance previous results for polystyrene silicon. suggest that air liquid-like layer exists whose size diverges as is approached from...
In simulations and experiments, we study the drying of films containing mixtures large small colloidal particles in water. During drying, mixture stratifies into a layer larger at bottom with smaller on top. We developed model to show that gradient osmotic pressure, which develops dynamically during is responsible for segregation mechanism behind stratification.
High quality opal-like photonic crystals containing graphene are fabricated using evaporation-driven self-assembly of soft polymer colloids. A miniscule amount pristine within a colloidal crystal lattice results in the formation with strong angle-dependent structural color and stop band that can be reversibly shifted across visible spectrum. The mechanically deformed or change as function their temperature, hence sensitive mechanochromic thermochromic response make them attractive candidates...
Abstract Pressure‐sensitive adhesives (PSAs) are made from soft, irreversibly lightly crosslinked polymers. Even after removal surfaces, they retain insoluble networks which pose problems during the recycling of glass and cardboard. Herein, degradable PSAs presented that provide required performance in use but have can be degraded use. A series copolymers was prepared through radical copolymerization n ‐butyl acrylate, 4‐acryloyloxy benzophenone (ABP) photo‐crosslinker,...
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTKinetics of Film Formation in Acrylic Latices Studied with Multiple-Angle-of-Incidence Ellipsometry and Environmental SEMJ. L. Keddie, P. Meredith, R. A. Jones, M. DonaldCite this: Macromolecules 1995, 28, 8, 2673–2682Publication Date (Print):April 1, 1995Publication History Published online1 May 2002Published inissue 1 April 1995https://pubs.acs.org/doi/10.1021/ma00112a012https://doi.org/10.1021/ma00112a012research-articleACS PublicationsRequest...
Abstract We have used ellipsometry to measure the glass transition temperature (T g ) of ultra‐thin films polystyrene (PS) (less than 20 nm thick) obtained by spin‐casting from solution onto silicon substrates. find that T in these is depressed bulk value qualitative accord with our earlier results on thicker PS. In as thin 8 nm, depression 35 K. also prepared ultra‐thins grafting PS‐COOH native oxide Si and Si. Here we been able 5‐nm which a 10 tentatively ascribe smaller for grafted chains...
Transparent and conductive pressure-sensitive adhesives are cast from aqueous colloidal dispersions of poly(butyl acrylate) (P(BuA)) functionalized carbon nanotubes (CNTs). At the percolation threshold for network formation (at only 0.3 wt % CNT), remarkably double amount strain at adhesive failure increase adhesion energy by 85 (see figure). The tack properties explained current models debonding.
The formation and characterization of close-packed monolayers negative, poly(N-isopropylacrylamide)-based microgel particles onto positively charged silicon wafers is described. were rendered positive by first oxidizing their surface to silica then adsorbing a layer poly(ethyleneimine). thickness the deposited (under aqueous conditions) has been determined spectroscopic ellipsometry as function temperature (20-60 degrees C), pH (3-8), added NaCl concentration (0-1 M). No actual desorption...
Waterborne polyurethane-acrylic hybrid nanoparticles for application as pressure-sensitive adhesives (PSAs) were prepared by one-step miniemulsion polymerization. The addition of polyurethane to a standard waterborne acrylic formulation results in large increase the cohesive strength and hence much higher shear holding time (greater than seven weeks at room temperature), which is very desirable characteristic PSAs. However, with cohesion, there decrease relative viscous component, tack...
A significant reduction in the electrical percolation threshold is achieved by locking carbon nanotubes (CNTs) a predominantly hexagonally close-packed (HCP) colloidal crystal lattice of partially plasticized latex particles. Contrary to other widely used processing where CNTs are randomly distributed within matrix, for first time, we show that excluding from occupying interior volume particles promotes formation nonrandom segregated network. The four times lower an ordered network made with...
In films cast from a colloidal dispersion comprising two particle sizes, we experimentally examine the distribution of particles normal to substrate. The concentrations at various positions in film are determined through atomic force microscopy and NMR profiling. results compared previously derived diffusional model. Evidence for driven stratification is found, but importance other flows also highlighted. conditions that enhance found be colloidally stable dispersion, low initial volume...
Self-stratification is found when drying concentrated binary suspensions of particles only the concentration small and size ratio are high enough.
In an externally imposed electrolyte (salt) concentration gradient, charged colloids drift at speeds of order one micrometre per second. This phenomenon is known as diffusiophoresis. systems with multiple salts and “crossed” salt gradients, a nonlocal component the electric field associated circulating (solenoidal) ion current can arise. in addition to conventional local that depends only on gradients. Here we report experimental observations verifying existence this contribution. To our...
Latex dispersions having a well-controlled, bimodal particle size distribution are gaining attention because they potentially enable control of the dispersion rheology, film formation characteristics, and final properties. Here we study with (large:small ratio ca. 6:1) varying concentrations two sizes. We also compare blends containing only deformable (i.e., "soft") particles both soft nondeformable "hard") particles. use ellipsometry as noninvasive tool for studying morphology proceeds....
Numerous synthesis routes toward nanostructured polymer particles have emerged, but few examples demonstrate the essential need for such complex particle structures to achieve any added benefit in a target application. Here, having Laponite clay armor were prepared by Pickering miniemulsion polymerization of n-lauryl acrylate. The resulting "soft–hard" poly(lauryl acrylate) (PLA)–Laponite hybrid blended at various low concentrations with standard poly(butyl acrylate-co-acrylic acid) (PBA)...
Although poor mechanical properties are usually found in films cast from waterborne colloidal polymers relative to their solvent counterparts, these materials offer the opportunity control structure and composition very precisely at nanoscale. Here, we introduce a knowledge-based strategy design what call "soft–soft nanocomposite" which percolating crosslinked phase contains second less dispersed distributed regularly throughout it. This new type of uses polymer colloid particles as building...
Semiconducting polymers have previously been used as the transduction material in x-ray dosimeters, but these devices a rather low detection sensitivity because of attenuation efficiency organic active layer. Here, we demonstrate way to overcome this limitation through introduction high density nanoparticles having atomic number (Z) increase attenuation. Specifically, bismuth oxide (Bi2O3) (Z = 83 for Bi) are added poly(triarylamine) (PTAA) semiconducting polymer layer an detector. Scanning...
A major drawback of conventional emulsion polymers arises from the presence migrating low molar mass surfactants that contribute to poor water barrier properties and adhesion substrates. In this paper, we demonstrate how living polymer chains obtained by reversible addition–fragmentation chain transfer (RAFT) can be used as an efficient stabilizer in polymerization, leading production surfactant-free latexes, which then form cross-linked films with beneficial properties. Hydrophilic...