Publications - 2001
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Special Issue on the 10th International Conference on Colloid and Interface Science held 23-28 July 2000 in Bristol, UK [In: Colloids Surf., A, 2001; 190(1-2)]
Editor: T. Cosgrove
212 pp. (2001) Publisher: (Elsevier Science B.V., Amsterdam, Neth.)
Abstract
Book written in English.
The 10th International Conference on Colloid and Interface Science, Bristol, 23-28 July 2000
T. Cosgrove
Bristol University, School of Chemistry, Bristol, UK
Colloids and Surfaces, A: Physicochemical and Engineering Aspects (2001), 190(1-2), 1. Publisher: Elsevier Science B.V.
Abstract
No abstract available
The Effects of Temperature and Methanol Concentration on the Properties of Poly(N-isopropylacrylamide) at the Air/Solution Interface
Robert Pelton, Robert Richardson, Terence Cosgrove and Robert Ivkov
McMaster Centre for Pulp and Paper Research Department of Chemical Engineering, McMaster University, Hamilton, ON, Canada
Langmuir (2001), 17(16), 5118-5120
Abstract
Neutron reflectivity was used to study the interfacial properties of poly(N-isopropylacrylamide) (polyNIPAM) on the surface of methanol/water, as a function of compn. and temp. The concn. of polyNIPAM at the soln./air interface is sensitive to the conditions in the soln. and three adsorption regimes are apparent. When the methanol concn. is above 65%, the surface concn. of polyNIPAM is essentially zero, which is consistent with the fact that pure methanol is a good solvent for polyNIPAM. The second regime occurs at lower alc. concns. and at temps. below the LCST [lower crit. soln. temp.]. Under these conditions, conventional adsorbed monolayers form. The third regime occurs above the LCST, where thick layers form in what is essentially the deposition of phase-sepd. polyNIPAM at the air/ soln. interface.
Dynamics and structure of polydimethylsiloxane emulsions as studied by pulsed field gradient NMR and small-angle neutron scattering
Tatjana Garasanin Bellenger, Terence Cosgrove, Andrew J. Goodwin, Axel Kretschmer, Leon Marteaux, Anthony J. Semlyen and Anthony Dagger
School of Chemistry, University of Bristol, Cantock's Close, Bristol, UK
Polymer Preprints (American Chemical Society, Division of Polymer Chemistry) (2001), 42(1), 124-125
Abstract
Polymeric oil-in-water emulsions consisting of polydimethylsiloxane and two surfactants, Brij 35p and Brij 30 were studied by high resoln. pulsed field gradient NMR spectroscopy and by small-angle neutron scattering. Optimum formulations for stability of the emulsions are detd.
Diffusion of Poly(dimethylsiloxane) Mixtures with Silicate Nanoparticles
Claire Roberts, Terence Cosgrove, Randall G. Schmidt and Glenn V. Gordon
School of Chemistry, University of Bristol, Bristol, UK
Macromolecules (2001), 34(3), 538-543 (Copyright 2001 ACS)
Abstract
Pulsed field-gradient (PFG) NMR has been used to measure self-diffusion coeffs. in mixts. of silicate nanoparticles with poly(dimethylsiloxane)s as a function of vol. fraction of particles and of polymer mol. wt. Two different sizes of nanoparticles were used: the smaller acted like a solvent, and the larger one acted more like a colloidal particle. In the former case, two distinct diffusion coeffs. were obtained, corresponding to the particle and the polymer. In the second case, only a signal from the polymer was evident because of the short spin-spin relaxation time (T2) of the particle. However, in this latter case the diffusional attenuation indicated the presence of both free polymer and locally mobile but translationally constrained polymer, characteristic of polymer adsorption from a liq. The data have been interpreted as a function of particle loading, and calcns. have been made to est. the thickness of the polymer layer using a hydrodynamic model.
Polymers at surfaces and interfaces, by R. A. L. Jones, R. W. Richards
Terence Cosgrove
School of Chemistry, University of Bristol, Bristol, UK
International Journal of Adhesion and Adhesives (2001), 21(2), 173
Abstract
Book Review written in English.
Dynamics and structure of polydimethylsiloxane emulsions as studied by pulsed field gradient NMR and small-angle neutron scattering
Terence Cosgrove, Tania Garasanin Bellenger, Andrew J. Goodwin, Axel Kretschmer and Leon Marteaux
School of Chemistry, University of Bristol, Bristol, BS8 1TS, UK
Abstracts of Papers, 221st ACS National Meeting, San Diego, CA, United States, April 1-5, 2001 (2001), POLY-222. Publisher: American Chemical Society
Abstract
Polymeric-oil in water emulsion have been made, using polydimethylsiloxane PDMS (350cS and 1000cS) fluids and two non-ionic surfactants: polyoxethylene (4) lauryl ether (Brij-30) and polyoxethylene (23) lauryl ether (Brij-35p). The emulsions have been prepd. using phase inversion methods and a high-speed mixer. The ratio of the two surfactants has been varied in order to find the compn. for the highest emulsion stability. High resoln. NMR techniques have been used to study the translational diffusion of the PDMS fluid, the surfactants and the water phase. Pulsed field gradient (PFG) NMR has been proven to be a very powerful technique for studying emulsion systems. One of the important applications of this method is the detn. of the droplet size distribution. This method has the advantage of covering the range from very concd. down to very dil. systems. For concd. systems, the restricted diffusion of the fluid inside the emulsion droplets is measured and the size distribution is obtained using a modified Murday and Cotts expression. For dil. systems the Brownian diffusion of the emulsions droplets has been measured for the first time and the size distribution was obtained from the Stokes-Einstein equation. The difference between free diffusion of the fluid, partially restricted diffusion, restricted and Brownian diffusion of the emulsion will be discussed. The stimulated spin-echo method (STE) is used in order to extend the limit of the PFG technique to large diffusion time. Photon correlation spectroscopy (PCS) and Fraunhofer diffraction studies (using the MasterSizer) to measure the particle size distributions compare very well with the NMR results. Small-angle neutron scattering has also been used to probe the structure of the surfactant film at the interface as function of the ratio of the two surfactants used. The results have been used to design and characterize the best formulation for making PDMS emulsions with long-term stability.
Diffusion of polydimethylsiloxane mixtures with silicate nanoparticles
Terence Cosgrove, Claire Roberts, Glen V. Gordon and Randall G. Schmidt
School of Chemistry, University of Bristol, Bristol, BS8 1TS, UK
Abstracts of Papers, 221st ACS National Meeting, San Diego, CA, United States, April 1-5, 2001 (2001), POLY-199. Publisher: American Chemical Society
Abstract
Fillers are frequently added to com. polymers to enhance their mech. properties without great expense. Despite the widespread use of such systems, there remains a need to provide a fundamental understanding of how their mech. properties are altered, and few techniques have proved suitable for studying such systems at a mol. level. In this presentation the system of interest consists of low mol. wt. polydimethylsiloxanes (PDMS) filled with trimethylsilyl-treated silicate nanoparticles. Pulsed field-gradient (PFG) NMR was used to measure self-diffusion coeffs. in mixts. of silicate nanoparticles with PDMS as a function of vol. fraction of particles and of polymer mol. wt. Two different sizes of silicate nanoparticles were used. The smaller silicate (R1) acted like a solvent, and the larger (R3) one behaved more like a colloidal particle. The data have been interpreted as a function of particle loading and calcns. have been made to est. the thickness of the polymer layer using the hydrodynamic model of Batchelor and assuming deviations from the pure particle behavior was due to the adsorbed layer of the 5k PDMS. The results are consistent with scaling theory predictions of adsorption from melts.
Surface, Interfaces and Colloids, Second Edition, Edited by Drew Myers
Terence Cosgrove
School of Chemistry, University of Bristol, Bristol, UK
Journal of Surfactants and Detergents (2001), 4(1), 115
Abstract
Book Review written in English.
Diffusion of Poly(dimethylsiloxane) Mixtures with Silicate Nanoparticles
Claire Roberts, Terence Cosgrove, Randall G. Schmidt and Glenn V. Gordon
School of Chemistry, University of Bristol, Bristol, UK
Macromolecules (2001), 34(3), 538-543
Abstract
Pulsed field-gradient (PFG) NMR was used to measure self-diffusion coeffs. in mixts. of silicate nanoparticles with poly(dimethylsiloxanes) as a function of vol. fraction of particles and of polymer mol. wt. Two different sizes of nanoparticles were used: the smaller acted like a solvent, and the larger one acted more like a colloidal particle. In the former case, two distinct diffusion coeffs. were obtained, corresponding to the particle and the polymer. In the second case, only a signal from the polymer was evident because of the short spin-spin relaxation time (T2) of the particle. However, in this latter case the diffusional attenuation indicated the presence of both free polymer and locally mobile but translationally constrained polymer, characteristic of polymer adsorption from a liq. The data have been interpreted as a function of particle loading, and calcns. have been made to est. the thickness of the polymer layer using a hydrodynamic model.
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