A5003677224- Block Copolymer Self-Assembly
- Polymer Surface Interaction Studies
- Micro and Nano Robotics
- Advanced Polymer Synthesis and Characterization
- Pickering emulsions and particle stabilization
- Force Microscopy Techniques and Applications
- Organic Electronics and Photovoltaics
- Molecular Communication and Nanonetworks
- Microfluidic and Bio-sensing Technologies
- Fluid Dynamics and Thin Films
- Surfactants and Colloidal Systems
- Advancements in Photolithography Techniques
- Hydrogels: synthesis, properties, applications
- Nanofabrication and Lithography Techniques
- Electrostatics and Colloid Interactions
- Rheology and Fluid Dynamics Studies
- Liquid Crystal Research Advancements
- Modular Robots and Swarm Intelligence
- Material Dynamics and Properties
- Thermochemical Biomass Conversion Processes
- Thin-Film Transistor Technologies
- Surface Modification and Superhydrophobicity
- Organic Light-Emitting Diodes Research
- Image Processing Techniques and Applications
- Integrated Circuits and Semiconductor Failure Analysis
University of Sheffield
2013-2023
University of Oxford
2014
University of Bristol
2014
Sheffield City Council
2014
Universiti Malaysia Pahang Al-Sultan Abdullah
2013
Loughborough University
2011
Aston University
2011
Rutherford Appleton Laboratory
2008
University of Bath
2008
Daresbury Laboratory
2005
The motion of an artificial microscale swimmer that uses a chemical reaction catalyzed on its own surface to achieve autonomous propulsion is fully characterized experimentally. It shown at short times it has substantial component directed motion, with velocity depends the concentration fuel molecules. At longer times, reverts random walk substantially enhanced diffusion coefficient. Our results suggest strategies for designing chemotactic systems.
This review describes recent developments in self-propelling nano- and micro-scale swimming devices. The ability of these devices to transport nano-scale components a fluidic environment is demonstrated. Furthermore, the adaptations needed for meet biological challenges such as targeted drug delivery are highlighted. Particular emphasis placed on describing autonomously powered driven by asymmetrical chemical reactions. Methods control speed direction using external fields described,...
Abstract The advent of autonomous self-propulsion has instigated research towards making colloidal machines that can deliver mechanical work in the form transport, and other functions such as sensing cleaning. While much progress been made last 10 years on various mechanisms to generate self-propulsion, ability steer self-propelled devices so far more limited. A critical barrier increasing impact motors is directing their motion against Brownian rotation, which randomizes particle...
The propulsion velocity of active colloids that asymmetrically catalyze a chemical reaction is probed experimentally as function their sizes. It found over the accessible range, decays size, with rate compatible an inverse size dependence. A diffusion-reaction model for concentrations fuel and waste molecules takes into account two-step process asymmetric catalytic activity on surface colloid shown to predict similar behavior at large limit, saturation smaller
The effect of added salt on the propulsion Janus platinum-polystyrene colloids in hydrogen peroxide solution is studied experimentally. It found that micromolar quantities potassium and silver nitrate salts reduce swimming velocity by similar amounts, while leading to significantly different effects overall rate catalytic breakdown peroxide. argued seemingly paradoxical experimental observations could be theoretically explained using a generalised reaction scheme involves charged...
In this paper we show that processes such as Brownian motion, convection, sedimentation, and bacterial contamination can cause small particles to move through liquids in a fashion which may be mistaken nanopropulsion. It is shown particle tracking subsequent statistical analysis essential ascertain if actually propel themselves, or they are propelled by another process. Specifically find it necessary calculate the mean-squared displacement of at both short long time intervals, direction...
Nonconductive Janus particle swimmers made by coating fluorescent polymer beads with hemispheres of platinum have been fully characterized using video microscopy to reveal that they undergo propulsion in hydrogen peroxide fuel away from the catalytic patch. The shadows fluorescence signal half each swimmer allow orientation be observed directly and correlated quantitatively resulting swimming direction. direction is consistent both bubble release diffusiophoretic mechanisms.
A class of artificial microswimmers with combined translational and rotational self-propulsion is studied experimentally. The chemically fueled are made doublets Janus colloidal beads catalytic patches that positioned at a fixed angle relative to one another. mean-square displacement the angular active analyzed in context simple Langevin description, using which physical characteristics such as spontaneous velocities extracted. Our work suggests strategies for designing could follow...
We report the use of solvent vapor swelling ultrathin polymer films to determine Flory–Huggins solvent–polymer and polymer–polymer interaction parameters (χi–j) for poly(3-hexylthiophene) (P3HT) polystyrene (PS) over a wide composition range. From calculated parameters, we constructed polymer/polymer/solvent phase diagram that was validated experimentally. χtetrahydrofuran–P3HT (1.04 ± 0.04) χCHCl3–P3HT (0.99 0.01) were determined through P3HT films. Similar experiments using PS gave...
Interaction of the tea polyphenol epigallocatechin gallate (EGCG) with β-casein in milk affects taste and also stability antioxidant ability EGCG. In addition, interaction polyphenols chemically similar salivary proline-rich proteins is largely responsible for astringency red wine. With use single molecule force microscopy, we demonstrate that EGCG a casein multivalent leads to reduction persistence length as calculated using wormlike chain model its radius gyration. The extra required...
A scalable synthetic muscle has been constructed that transducts nanoscale molecular shape changes into macroscopic motion. The working material, which deforms affinely in response to a pH stimulus, is self-assembled block copolymer comprising nanoscopic hydrophobic domains weak polyacid matrix. device assembled where the does work on cantilever and force generated measured. When coupled chemical oscillator this provides free running motor generates peak power of 20 mW kg-1 by serial...
Model poly(glycerol monomethacrylate)-based macromonomers have been used to prepare sterically stabilized polystyrene latexes by either aqueous emulsion or alcoholic dispersion polymerization, affording mean latex diameters of approximately 107 1188 nm respectively as judged dynamic light scattering. Such PGMA50−PS appropriate surface wettability stabilize 25−250 μm oil-in-water Pickering emulsions, depending on the concentration and oil type. Colloidosomes were formed covalent cross-linking...
Composition control in multi-component low molecular weight hydrogels can be achieved, using an electrochemically triggered approach.
Spin coating polymer blend thin films provides a method to produce multiphase functional layers of high uniformity covering large surface areas. Applications for such include photovoltaics and light-emitting diodes where performance relies upon the nanoscale phase separation morphology spun film. Furthermore, at micrometer scales, route self-organized structures templating applications. Understanding factors that determine final phase-separated in these systems is consequently an important...
ADVERTISEMENT RETURN TO ISSUEPREVCommunication to the...Communication the EditorNEXTAntagonistic Triblock Polymer Gels Powered by pH OscillationsPaul D. Topham, Jonathan R. Howse, Colin J. Crook, Steven P. Armes, Richard A. L. Jones, and Anthony RyanView Author Information Department of Chemistry, University Sheffield, S3 7HF, U.K., Physics Astronomy, 7RH, U.K. Cite this: Macromolecules 2007, 40, 13, 4393–4395Publication Date (Web):June 1, 2007Publication History Received8 May 2007Revised14...
We report the effect of a range monovalent sodium salts on molecular equilibrium swelling simple synthetic microphase separated poly(methyl methacrylate)-block-poly(2-(diethylamino)ethyl methacrylate)-block-poly(methyl methacrylate) (PMMA88-b-PDEA223-b-PMMA88) pH-responsive hydrogel. Sodium acetate, chloride, bromide, iodide, nitrate and thiocyanate were selected for study at controlled ionic strength pH; all are taken from Hofmeister series (HS). The influence anions expansion hydrogel was...
The field of active colloids is attracting significant interest to both enable applications and allow investigations new collective colloidal phenomena. One convenient system that has been much studied spherical Janus particles, where a hemispherical coating platinum decomposes hydrogen peroxide produce rapid motion. However, at present producing these relies on physical vapor deposition (PVD) process, which difficult scale requires access expensive equipment. In this work, it demonstrated...
Through the technique of stroboscopic microscopy we are able to directly identify a number different mechanisms by which colloids self-assemble during spin-coating.
Controlling polymer thin-film morphology and crystallinity is crucial for a wide range of applications, particularly in organic electronic devices. In this work, the crystallization behavior model polymer, poly(ethylene oxide) (PEO), during spin-coating studied. PEO films were spun-cast from solvents possessing different polarities (chloroform, THF, methanol) probed via situ grazing incidence wide-angle X-ray scattering. The was found to follow solvent polarity order (where chloroform < THF...
A series of novel block copolymers, processable from single organic solvents and subsequently rendered amphiphilic by thermolysis, have been synthesized using Grignard metathesis (GRIM) reversible addition–fragmentation chain transfer (RAFT) polymerizations azide–alkyne click chemistry. This chemistry is simple allows the fabrication well-defined copolymers with controllable lengths. The designed for use as interfacial adhesive layers in photovoltaics to enhance contact between photoactive...
Progress in the development of generic molecular devices based on responsive polymers is discussed. Characterisation specially synthesised polyelectrolyte gels, "grafted from" brushes and triblock copolymers reported. A Landolt pH-oscillator, bromate/ sulfite/ferrocyanide, with a room temperature period 20 min range 3.1 < pH 7.0, has been used to drive periodic oscillations volume hydrogel. The gel coupled reaction changes by factor at least 6. continuously stirred, constant volume, tank...