Collapse of polymer brushes grafted onto planar ... - Wageningen UR

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COIL-SIZE OSCILLATORY PACKING IN POLYMER SOLUTIONS NEAR A SURFACE J. van der Gucht, N.A.M. Besseling, J. van Male, M.A. Cohen Stuart Laboratory of Physical Chemistry and Colloid Science, Wageningen University, Dreijenplein 6, 6703 HB Wageningen, The Netherlands email: jasper@fenk.wau.nl ABSTRACT Depletion of polymers at a surface has been studied extensively before. Theories predict that the segment concentration profile decreases monotonously with decreasing distance to the surface 1,2) . Furthermore it is generally accepted that the only relevant lengthscale above the overlap concentration is the “blob size”. The coil size is believed to be irrelevant in this regime 1,2) . We have performed detailed calculations of the density profile of nonadsorbing polymers near a surface, using the theory developed by Scheutjens and Fleer 1) . Our results indicate that there is a damped oscillatory contribution to the density profile. Both the period of the oscillations and the decay length are proportional to the size of the individual coils and are independent of the polymer concentration, also above the overlap concentration. This indicates that the size of the individual coils is still a relevant lengthscale above the overlap concentration. The oscillations are associated with a liquid-like layering of polymer coils near the surface. In dilute solutions no oscillations are observed, because the decay length of the oscillations is smaller than the depletion correlation length. This is similar to the behaviour of simple fluids, where the Fisher-Widom line marks the transition from monotonic to oscillatory decay of the density correlation function 3) . The Fisher-Widom line in polymer solutions is proportional to the overlap concentration. On the oscillatory side of the Fisher-Widom line the interaction energy between two plates immersed in a solution of nonadsorbing polymers is an oscillatory function of the separation distance. The size of the oscillations is too small to be detected experimentally, but the effect is expected to be stronger in for example branched polymer solutions. As indicated by Evans et al. the oscillations might be of importance in, for example, wetting phenomena 4) . References 1. Fleer, G.J., Cohen Stuart, M.A., Scheutjens, J.M.H.M.; Cosgrove, T., Vincent, B. Polymers at Interfaces. Chapman and Hall: London, 1993. 2. De Gennes, P.G., Scaling Concepts in Polymer Physics; Cornell University Press: Ithaca, London. 3. Fisher, M.E., and Widom, B., 1969. J. Chem. Phys. 50, 3756. 4. Evans, R., Leote de Carvalho, R.J.F., Henderson, J.R. and Hoyle, D.C., 1993. J. Chem. Phys., 100, 591.
SUPRAMOLECULAR COORDINATION POLYMERS: CHAINS AND RINGS J. van der Gucht Laboratory of Physical Chemistry and Colloid Science, Wageningen University, Dreijenplein 6, 6708 HB Wageningen, The Netherlands email: jasper@fenk.wau.nl ABSTRACT Bifunctional monomers were synthesized, consisting of two ligand groups bridged by a short spacer. With metal ions, these molecules can form coordination polymers. This can be monitored by measuring the viscosity. For linear chains one expects a maximum in the visocity at a 1:1 ratio of metal to monomers. At low concentrations however, a dip is measured there. This dip can be explained using a simple model for equilibrium polymerization into rings and chains, which predicts that short rings dominate at low concentrations at a 1:1 ratio, causing a minimum in the average length, and, hence, in the viscosity.
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Frontis - Wageningen International
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Prof. dr. Hans Fraaije Leiden Unive
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Prof. Ullrich Steiner University of
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Preface Self-consistent field model
Page 9 and 10: covered by polymers), and R. Rajago
Page 11 and 12: FIRST-ORDER WETTING TRANSITION AT F
Page 13 and 14: MOLECULAR SCF MODELLING OF PORES IN
Page 15 and 16: COLLAPSE OF POLYMER BRUSHES GRAFTED
Page 17 and 18: SURFACE FORCES, SUPRAMOLECULAR POLY
Page 19 and 20: SWEET BRUSHES: SYNTHESIS AND INTERF
Page 21 and 22: EFFECT OF MIXING OF TWO CHARGED PHO
Page 23 and 24: Figure 2 show a semi-log comparison
Page 25 and 26: MODELING OF STATIONARY POLYMER DIFF
Page 27 and 28: THEORY AND SIMULATION OF BILAYER ME
Page 29 and 30: Figure 1. Time evolution of the she
Page 31 and 32: SALT EFFECT TO RAYLEIGH DROPLETS OF
Page 33 and 34: MACROMOLECULES AT INTERFACES, A FLE
Page 35 and 36: APPLICATION OF HETEROGENEOUS LATTIC
Page 37 and 38: 8. Linse, P., 1993b. Phase behavior
Page 39 and 40: MODELING INTERFACIAL EFFECTS ON THE
Page 41 and 42: Using this patterned electrode, we
Page 43 and 44: span the gap between the electrodes
Page 45 and 46: desirable to use a probe with a muc
Page 47 and 48: span the gap between the electrodes
Page 49 and 50: MEMBRANE FUSION: RESULTS FROM SIMUL
Page 51 and 52: the transition temperature T * when
Page 53 and 54: PROTEIN ADSORPTION ON SURFACES WITH
Page 55 and 56: MODELLING STRUCTURE AND ADHESION AT
Page 57 and 58: References 1. Fischel, L.B. and The
Page 59: MULTIDOMAIN CONFORMATIONS OF RANDOM
Page 63 and 64: INFLUENCE OF POLYMERS ON THE BENDIN
Page 65 and 66: SPINODAL DECOMPOSITION IN BINARY PO
Page 67 and 68: PERSISTENCE LENGTH OF WORM-LIKE MIC
Page 69 and 70: For small particles with radius R <
Page 71: MEAN-FIELD THEORY FOR THE ADSORPTIO
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