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CAPILLARY-INDUCED FORCES BETWEEN PARTICLES IN POLYMER SOLUTIONS NEAR PHASE SEPARATION M. Olsson, F. Joabsson, P. Linse, L. Piculell Physical Chemistry 1, Center for Chemistry and Chemical Engineering, Lund University, P.O. Box 124, S-221 00 Lund email: Martin.Olsson@fkem1.lu.se ABSTRACT Capillary-induced phase separation (CIPS) leads to a long-ranged attractive force between two surfaces immersed in a bulk solution. The formation of a new phase in the gap between the surfaces is driven by a lower surface energy for the new (capillary) phase compared to the bulk phase. The decrease in free energy is larger at shorter separations between the particles than for longer ones. An important condition for CIPS to arise is that the particle-free solution has to be close to phase separation. CIPS forces are known to affect particle aggregation in mixed solvents and in polymer blends as well as protein aggregation in biological membranes. We have instead looked at polymer solutions with added colloidal dispersed particles both experimentally and theoretically. Previous surface force measurements have showed that CIPS occurs in mixed polymer solutions as well as in quasi-binary polymer solutions [1,2]. A complementary experimental study [3] for the mixed polymer system displays phase separation at compositions far into the one-phase area for the original phase diagram, when colloidal particles are added. To investigate more generally the parameters affecting CIPS for the mixed polymer system, a theoretical mean-field lattice study has been done [4]. This study shows that CIPS occurs close to phase separation for the system and is affected by parameters like the molecular weight of the polymer, the affinity of the polymer to the surface, the composition of the sample and the distance between the particles. A recent study [5] shows that CIPS can also appear in quasi-binary solutions. This has also been shown experimentally. References 1. Freyssingeas, E., Thuresson, K., Nylander, T., Joabsson, F., Lindman, B., 1998. Langmuir 14, 5877-5889. 2. Wennerström, H., Thuresson, K., Linse, P., Freyssingeas, E., 1998. Langmuir 14, 5664-5666. 3. Joabsson, F., Calatayu, A., Thuresson, K., Piculell, L., submitted. Journal of Physical Chemistry B. 4. Joabsson, F. and Linse, P. “Capillary-Induced Phase Separation in Mixed Polymer Solutions. A Lattice Mean-Field Calculation Study”, manuscript. 5. Olsson, M., Linse, P., Piculell, L. “Capillary-Induced Phase Separation in Binary and Quasi-binary Solutions. A Lattice Mean-Field Calculation Study”, manuscript.
span the gap between the electrodes. Throughout the course of growth, the characteristic wavelength remains invariant. The characteristic length scale coupled with the sharpening of the peaks of the fluctuations gives rise to a hexagonal packing of the cylinders laterally. By replacing the air gap with a second fluid or polymer layer between the electrodes reduces the energetic cost of generating interfacial area by replacing the surface energy with an interfacial energy. In general, the interfacial energy is approximately one order of magnitude smaller than the surface energy. This translates into a reduction in the characteristic fluctuation wavelength. The experimentally measured wavelengths are in excellent agreement with the predictions. Theoretically, significant changes are unexpected, but a significant decrease is observed. While unexpected, this represents a tremendous advantage for end-use of this phenomenon.
Page 1 and 2: Frontis - Wageningen International
Page 3 and 4: Prof. dr. Hans Fraaije Leiden Unive
Page 5 and 6: Prof. Ullrich Steiner University of
Page 7 and 8: 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: Using this patterned electrode, we
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 and 60: MULTIDOMAIN CONFORMATIONS OF RANDOM
Page 61 and 62: SUPRAMOLECULAR COORDINATION POLYMER
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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