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Publications - 1987

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Neutron scattering from adsorbed polymer layers

Terence Cosgrove, Timothy G. Heath, Keith Ryan and Trevor L. Crowley
Department of Physical Chemistry, University of Bristol, Bristol, UK.

Macromolecules (1987), 20(11), 2879-82


Small-angle neutron scattering data of poly(ethylene oxide) and hydrolyzed poly(vinyl acetate) adsorbed on perdeuterated polystyrene latexes with zero contrast between the particle and solvent could be used to obtain the vol. fraction profile of the adsorbed layer. The scattering was detd. by the av. structure of the adsorbed layer and not by fluctuations in the structure. The use of scattering data away from zero contrast to obtain the vol. fraction profile was unsatisfactory due to difficulties in obtaining data for the Guinier approxn. and of scattering by the particle.

Spectral phasing by reconstruction of partial spin echoes

Terence Cosgrove, Trevor L. Crowley and Mark Morgan
School of Chemistry, University of Bristol, Bristol, UK

J. Magn. Reson. (1987), 73(3), 487-92


An anal. and method are described for constructing complete spin echoes from partial echoes. A min. of 1 point on the rising part of the echo envelope is required. The advantage of this technique over conventional methods is that it removes the necessity for phase correction in the spectrum and the resultant spectral amplitudes are not necessarily dependent on T2. This method should find many applications in high-resoln. NMR and in expts. where partial spin echoes are produced.

On the kinetics and reversibility of polymer adsorption

Terence Cosgrove and James W. Fergie-Woods
School of Chemistry, University of Bristol, Bristol, UK

Colloids Surf. (1987), 25(1), 91-9


The rates of adsorption and desorption of polystyrene at the solid/soln. interface were measured by using NMR. The fraction of segments of adsorbed polymer chains detected by high resoln. NMR was estd. by using the Scheutjens-Fleer theory of polymer adsorption. The time of attainment of the equil. configuration is considerably longer than that suggested by the diffusion time to the surface. Reversible adsorption is found, both by diln. and by concn. of the polymer soln.

Configuration of terminally attached chains at the solid/solvent interface: self-consistent field theory and a Monte Carlo model

Terence Cosgrove, Timothy Heath, Boudewijin Van Lent, Frans Leermakers and Jan Scheutjens
School of Chemistry, University of Bristol, Bristol, UK

Macromolecules (1987), 20(7), 1692-6


Segment d. distributions, root mean square (rms) thicknesses, and bound fractions were calcd. for terminally attached chains at the solid/solvent interface. The effects of coverage, solvent quality, and adsorption energy were considered. Both the SCF theory of Scheutjens and Fleer and a Monte Carlo method were used. The results showed a marked difference between systems with adsorption energies above and below the crit. value. Solvency had a significant effect on the variation of the rms thickness with chain length. At high coverages, polymer conformations with small bound fractions and highly extended tails were found. Differences between the two models were discussed.

The conformation of adsorbed poly(ethylene oxide) at the polystyrene/water interface

T. Cosgrove, T. G. Heath, K. Ryan and B. Van Lent
Department of Physical Chemistry, University of Bristol, Bristol, UK

Polym. Commun. (1987), 28(3), 64-5


Small-angle neutron scattering was used to det. the configuration of poly(ethylene oxide) phys. adsorbed from soln. and terminally attached to polystyrene latex in H2O. The results were compared to theor. predictions of mean-field calcns. Good agreement was found between theory and expts.

Self-consistent field theory for the adsorption of ring polymers from solution

Boudewijn Van Lent, Jan Scheutjens and Terence Cosgrove
Agric. Univ., Wageningen, Netherlands

Macromolecules (1987), 20(2), 366-70


The SCF polymer adsorption theory of Scheutjens and G. J. Fleer (1980) is extended for the case of ring macromols. This is achieved by enumerating the chain conformations in 3 dimensions while maintaining a mean field approxn. to calc. the different interaction enthalpies. A comparison of the adsorption of rings and linear chains shows that under certain phys. conditions the adsorbed amt. of rings is higher, whereas in other cases the reverse is true. The vol. fraction of segments in trains and loops is calcd. as are the root-mean-square thickness and bound fractions for different values of the adsorption energy and for a variety of different solvency conditions.

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