Publications - 1994
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SANS studies of the interaction of SDS micelles with gelatin, and the effect of added salt
R.K. Heenan, S.J. White, T. Cosgrove, A. Zarbaksh, A.M. Howe and T.D. Blake
Rutherford Appleton Laboratory, Didcot/Didcot, UK
Prog. Colloid Polym. Sci. (1994), 97(Trends in Colloid and Interface Science VIII), 316-20
Abstract
The structural interaction between the anionic surfactant sodium dodecyl sulfate (SDS) and the biopolymer gelatin has been studied using SANS. The effect of adding excess salt has been examd. Micelles of SDS are strongly coupled to gelatin; intermicellar interactions dominate the structure at low ionic strength while at high ionic strength the polymer network dictates the intermicellar sepns.
Polymer Surfaces and Interfaces II
edited by W.J. Feast and H.S. Munro
T. Cosgrove
School of Chemistry, University of Bristol, Bristol, UK
Trends Polym. Sci. (Cambridge, U. K.) (1994), 2(12), 440; Publisher: Elsevier
Abstract
Book Review written in English
Colloidal dispersions of silica containing physisorbed β-casein-a solvent NMR relaxation study
T. Cosgrove, S.J. Mears and P.C. Griffiths
School of Chemistry, University of Bristol, Bristol, UK
Colloids Surf., A (1994), 86 193-200
Abstract
Spin-spin relaxation rate measurements have been performed on the solvent in aq. silica dispersions contg. a physisorbed polyelectrolyte, the milk protein β-casein. An enhancement in the relaxation rate resulting from the adsorption of β-casein at the silica interface has been studied as a function of pH, protein concn. and ionic strength. Adsorption occurred over a narrow pH range. The conventional adsorption isotherm was measured and allowed a bound fraction to be extd. from the relaxation rate data. With increasing ionic strength, the adsorbed amt. was found to increase.
Monte Carlo simulation of nonionic surfactants at the oil-water interface
Maki Ito and Terence Cosgrove
School of Chemistry, University of Bristol, Bristol, UK
Mol. Simul. (1994), 12(3-6), 393-6
Abstract
A Monte Carlo simulation method was developed for modeling amphiphiles at an oil-water interface. Properties are calcd. for the mixt. water, benzene and tetraoxyethylene glycol dodecyl ether.
Polymers at Interfaces
G.J. Fleer, M.A. Cohen Stuart, J.M.H.M. Scheutjens, T. Cosgrove and B. Vincent
School of Chemistry, University of Bristol, Bristol, UK
502 pp. Publisher: Chapman & Hall, London, UK; 1993
Abstract
Book written in English
Polymers at Interfaces
(A Collection of Papers Presented at the Polymers at Interfaces Conference, held at Bristol University, 8-10 September 1993.) [In: Colloids Surf., A. 1994; 86]
Editors: Th.F. Tadros and T. Cosgrove
School of Chemistry, University of Bristol, Bristol, UK
331 pp. Publisher: Elsevier, Amsterdam, Neth.; 1994
Abstract
Book written in English
Adsorption studies of different end-functionalized linear poly(dimethylsiloxane)
A. Patel, T. Cosgrove, J.A. Semlyen, J.R.P. Webster and J.M.H.M. Schuetjens
Dep. Chemistry, Univ. of York, York, UK
Colloids Surf., A (1994), 87(1), 15-24
Abstract
The adsorption of end-functionalized poly(dimethylsiloxane) (PDMS), of both low and high mol. wt., on to silica and alumina from carbon tetrachloride has been investigated by Fourier transform IR spectroscopy. The adsorbed amts. of these end-functionalized PDMS depend strongly on the compn. of the polymer; samples with end groups having a high surface affinity were found to adsorb to a greater extent. Detailed information on the structure of the adsorbed layer obtained by the Scheutjens-Fleer theor. model and a Monte Carlo simulation indicated that polymers with such end groups adsorb primarily as loops, with fewer segments in trains and tails compared with a homopolymer. Adsorption was found to be greater on alumina than on silica for both mol. wt. series.
Terminally Attached Polystyrene Chains on Modified Silicas
T. Cosgrove, T.G. Heath and K. Ryan
School of Chemistry, University of Bristol, Bristol, UK
Langmuir (1994), 10(10), 3500-6
Abstract
Polystyrene of various mol. wts. has been terminally grafted onto surface-modified silicas. The structure of these adsorbed layers was studied by SANS. As was found for homopolymer adsorption, grafted layers in which the polymer also phys. adsorbs show no evidence of scattering from fluctuations at the highest scattering vector studied (0.7 nm-1). Expts. carried out where the particle scattering length d. has been matched to the substrate give virtually the same vol. fraction profiles as do those which are not matched. However, for a system where the polymer does not phys. adsorb, it is not possible to give an abs. indication of a possible contribution from fluctuations at high Q because of uncertainty in the background scattering. This problem can be overcome by fitting the data sets such that any Lorentzian contribution at high Q is effectively eliminated, minimizing any anomalous scattering. The results are compared with mean-field calcns. and scaling predictions for polymer adsorption. For systems where the adsorption enthalpy is unfavorable, the vol. fraction profiles of the adsorbed layer show a distinct max., whose position depends on mol. wt. and surface coverage. The root-mean-square thickness of the adsorbed layer in this case follows reasonably well the scaling prediction of Alexander and de Gennes. For favorable values of the adsorption enthalpy, the vol. fraction profiles fall monotonically in a manner similar to that found for homopolymer adsorption.
Surface force and neutron scattering studies on adsorbed poly(2-vinylpyridine)-b-polystyrene
Terence Cosgrove, John S. Phipps, Robert M. Richardson, Michael L. Hair and David A. Guzonas
School of Chemistry, University of Bristol, Bristol, UK
Colloids Surf., A (1994), 86 91-101
Abstract
A low-mol.-wt., highly asym. block poly(vinylpyridine)-polystyrene has been adsorbed on silica particles suspended in toluene soln.; the system was examd. using small-angle neutron scattering (SANS). The results are compared with theor. calcns. based on the Evers-Scheutjens-Fleer model. The same polymer has been adsorbed on mica in the surface-force app. Both the extended length of the polymer in toluene and the amt. adsorbed are in good agreement with previous scaling predictions in the literature. Changing the solvent is complicated in the particulate system, because flocculation is induced by theta or below-theta solvents. However, the SANS data clearly show the shrinking of the polymer in the poorer solvents and the increase in vol. fraction close to the surface. The scaled length of highly asym. block copolymers can be rationalized in terms of the breakdown of the uniformly wetting anchor film, but it is pointed out that slow adsorption kinetics could give rise to the same scaling.
The measurement of volume fraction profiles for adsorbed polymers under compression using neutron reflectometry
T. Cosgrove, P. F. Luckham, R.M. Richardson, J.R.P. Webster and A. Zarbakhsh
School of Chemistry, University of Bristol, Bristol, UK
Colloids Surf., A (1994), 86 103-10
Abstract
A new surface force app. is described which enables simultaneous measurement of the interaction forces between adsorbed polymer layers as well as their surface structure by neutron reflectometry. The app. utilizes 2 optically flat quartz plates that are brought together by applying a known external force. Surface force and structural profiles have been obtained for polystyrene adsorbed on quartz from cyclohexane, i.e., a poor solvent.
Atomistic simulation of short-chain polymers at the liquid/liquid interface
Maki Ito and Terence Cosgrove
School of Chemistry, University of Bristol, Bristol, UK
Colloids Surf., A (1994), 86 125-31
Abstract
The structure of short-chain diblock copolymers adsorbed at the interface between two immiscible liqs. has been simulated using an atomistic level computer simulation. A rotational isomeric search is carried out to obtain the chain flexibility, and the equil. interfacial structure is studied by the Metropolis Monte Carlo procedure. The interface is characterized by no. d. profiles of the components comprising the simulated systems.
Characterization of adsorbed polymer layers using NMR solvent diffusion studies
T. Cosgrove and P.C. Griffiths
School of Chemistry, University of Bristol, Bristol, UK
Colloids Surf., A (1994), 84(2-3), 249-58
Abstract
A new method is discussed for estg. the av. concn. of adsorbed polymer layers in concd. dispersions from NMR solvent diffusion measurements. The av. concn. of the adsorbed polymer layer modeled as a spherical block is shown to depend on particle vol. fraction, polymer mol. wt., and adsorbed amt. Desorption has also been induced and the removal of the layer obsd. through changes in the diffusional behavior of the solvent.
The critical overlap concentration measured by pulsed field gradient nuclear magnetic resonance techniques
T. Cosgrove and P.C. Griffiths
School of Chemistry, University of Bristol, Bristol, UK
Polymer (1994), 35(3), 509-13
Abstract
The absence of any crit. effects around c* (crit. overlap concn.) in the diffusional behavior of a range of mol. wts. of narrow-fraction polystyrene in CCl4 is reexamd. Anal. of the mol. wt.-dependent concn. coeffs. of the concn. dependence shows sharp transitions between the dil. and semi-dil. behavior. Spin-spin relaxation time measurements are also performed and yield a value for c*. These values and other calcd. and measured values are discussed in terms of the spectrum of motions present in a polymer system.
Self-diffusion, viscosity and spin-spin relaxation in liquid poly(propylene oxide) melts
T. Cosgrove, P.C. Griffiths and J.R.P. Webster
School of Chemistry, University of Bristol, Bristol, UK
Polymer (1994), 35(1), 140-4
Abstract
Self-diffusion, viscosity and spin-spin relaxation have been measured for a series of low-mol.-wt. liq. poly(propylene oxide) melts. The data are discussed within the framework of theories commonly invoked for polymer dynamics including the Rouse chain and free-vol. effects. The av. diffusion coeffs. of a range of bimodal blends have also been measured and the results interpreted using the Rouse model.
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