| Institution: | 1. FORTH/Institute of Electronic Structure and Laser, P.O. Box 1527, 711 10 Heraklion, Greece
Department of Materials Science and Technology, University of Crete, Heraklion, Greece;2. FORTH/Institute of Electronic Structure and Laser, P.O. Box 1527, 711 10 Heraklion, Greece;3. Department of Microsystems Engineering, IMTEK, University of Freiburg, Georges-Köhler Allee 103, 79110, Freiburg, Germany |
| Abstract: | The dynamics of the concentration fluctuations in end-grafted polystyrene brushes in a theta solvent (cyclohexane) are probed by evanescent wave dynamic light scattering at different wavevectors q and temperatures. When the solvent quality changes from marginal to poor, the relaxation function C(q, t) exhibits strong effects as compared with the smooth variation of the brush density profile. From a single exponential above 50 °C, C(q, t) becomes a two-step decay function. The fast decay is still assigned to the cooperative diffusion albeit slower than in the good solvent regime whereas the slow nonexponential and nondiffusive process might relate to microsegragated and/or chain dynamics in the present polydisperse brush. The relaxation function of the present three brushes with different grafting density reveals similarities and disparities between wet brushes and semidilute polymer solutions. © 2006 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 44: 3590–3597, 2006 |
