Publications - 1995
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Adsorption studies on mixed silica-polymer-surfactant systems
T. Cosgrove, S.J. Mears, L. Thompson and I. Howell
School of Chemistry, University of Bristol, Bristol, UK
ACS Symp. Ser. (1995), 615(Surfactant Adsorption and Surface Solubilization), 196-204
Abstract
Photon correlation spectroscopy measurements have been performed on aq. silica dispersions contg. physisorbed poly(ethylene oxide) in the presence of the surfactant sodium dodecyl sulfate. From the measurements, it appeared that near complete desorption of the polymer occurred around the crit. micelle concn. of the pure surfactant. However, at very high surfactant concns., the apparent hydrodynamic thickness returned to its initial value in the absence of surfactant. The results are discussed in terms of the specific interactions between the polymer and the surfactant.
Polymer interfaces - structure and strength
Terence Cosgrove
School of Chemistry, University of Bristol, Bristol, UK
Chem. Ind. (London) (1995), (23), 975-6
Abstract
News Announcement written in English
Diffusion in bimodal and polydisperse polymer systems: 2. Fully protonated bimodal and polydisperse polymer solutions
T. Cosgrove and P.C. Griffiths
School of Chemistry, University of Bristol, Bristol, UK
Polymer (1995), 36(17), 3343-7
Abstract
In the second of two papers studying diffusion in bimodal and polydisperse polymer solns., the av. self-diffusion coeff. of two polydisperse polystyrene samples has been measured as a function of concn. by the pulsed-field-gradient NMR technique. Utilizing the concepts introduced in the previous paper, ests. of the mol.-wt. distribution obtained from these self-diffusion coeffs. show reasonable agreement with values obtained from gel-permeation chromatog. Simple model systems reinforce the validity of this approach.
Diffusion in bimodal and polydisperse polymer systems: 1. Bimodal solutions of protonated and deuterated polymers
T. Cosgrove and P.C. Griffiths
School of Chemistry, University of Bristol, Bristol, UK
Polymer (1995), 36(17), 3335-42
Abstract
In the first of two papers studying diffusion in bimodal and polydisperse polymer solns., the self-diffusion coeffs. of various protonated polymers in a series of bimodal solns. contg. deuterated polymers have been measured. Utilizing the chem. specificity of the pulsed-field gradient NMR (p.f.g.n.m.r.) technique, it was possible to study the effects of both mol. wt. and concn. of each component. A simple friction dependence was shown to account for the obsd. trends. The p.f.g.n.m.r. results are contrasted with mutual-diffusion-coeff. measurements, obtained from multi-tau photon-correlation spectroscopy on similar bimodal systems.
Adsorption of polystyrene-poly(ethylene oxide) block copolymers on quartz using a parallel-plate surface-force apparatus and simultaneous neutron reflection
Terence Cosgrove, Ali Zarbakhsh, Paul F. Luckham, Michael L. Hair and John R.P.W. Webster
School of Chemistry, University of Bristol, Bristol, UK
Faraday Discuss. (1995), Volume Date 1994, 98(Polymers at Surfaces and Interfaces), 189-201
Abstract
Block copolymers of polystyrene and poly(ethylene oxide) adsorbed on quartz plates under compression have been studied using neutron reflectometry. Adsorption from a good solvent (toluene) leads to the preferential adsorption of the ethylene oxide chains, but because of the very high asymmetry of the polymers and the favorable adsorption energy, the polystyrene is also adsorbed. The extent of the polystyrene adsorbed layer is less than the radius of gyration for both samples studied. On the approach of a second coated plate, the polystyrene vol. fraction increases near the interface, indicative of a strong interlayer repulsion. On changing the solvent to octane the profiles indicate collapse of the polymer layer and there is a dramatic decrease in the pressure required to hold the quartz plates at the same sepn.
Polymer Adsorption. The Effect of the Relative Sizes of Polymer and Particle
T. Cosgrove, P.C. Griffiths and P.M. Lloyd
School of Chemistry, University of Bristol, Bristol, UK
Langmuir (1995), 11(5), 1457-63
Abstract
The adsorption of relatively large polymers onto the surfaces of small particles is, potentially, fundamentally different from the "normal" case where the substrate is assumed to be locally flat. In a concd. dispersion of small particles, the sepn. of the particles is such that a large polymer may bridge the gap between two adjacent surfaces dependent on the surface coverage and the manner in which the adsorption sample is prepd. In this paper, we present data from small-angle neutron scattering (SANS) of high mol. wt. poly(ethylene oxide) (PEO) adsorbed onto colloidal silica and solvent relaxation studies of a smaller PEO sample adsorbed onto a range of different sized silica particles. The effects of particle size and concn. and polymer mol. wt. and concn. have been studied. Mol. dynamics (MD) simulations illustrate the importance of the relative sizes of the adsorbent and adsorbate.
Small-Angle Scattering Studies of Sodium Dodecyl Sulfate Interactions with Gelatin. 1.
Terence Cosgrove, Sarah J. White, Ali Zarbakhsh, Richard K. Heenan and Andrew M. Howe
School of Chemistry, University of Bristol, Bristol, UK
Langmuir (1995), 11(3), 744-9
Abstract
The structural perturbations that result from the interactions between the anionic surfactant SDS and the biopolymer gelatin were studied by using small-angle neutron scattering. In particular, contrast variation was used to highlight the various components in the mixt. The authors discuss these data in terms of structural changes assocd. with the individual components and their interactions with each other. The effect of ionic strength on these structures is also considered.
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