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|Author(s):||N P. Balsara; B A. Garetz; M C. Newstein; Barry J. Bauer; T J. Prosa;|
|Title:||Evolution of Microstructure in the Liquid and Crystal Directions in a Quenched Block Copolymer Melt and Its Implication on Phase Transition Mechanisms|
|Published:||November 01, 1998|
|Abstract:||Evolution of the disorder-to-order transition within a block copolymer is studied by the thermal quenching of samples from the melt to an ordered state. The ordered state consists of cylinders arranged on a hexagonal lattice and has liquid crystalline symmetry with liquid-like disorder along the cylinders axis and crystalline order in the hexagonal plane. We monitor the kinetics of microstructure formation in the liquid and crystalline directions by a combination of time-resolved depolarized light scattering and small angle x-ray scattering experiments. At small quench depths, microstructure formation along the liquid and crystalline directions is strongly correlated during all stages of the disorder-to-order transition. We demonstrate that this is expected when microstructure formation occurs by classical nucleation and growth; however, at large quench depths microstructure formation along the liquid and crystalline directions is not correlated. The growth of crystalline order occurs before the development of a coherent structure along the liquid direction. We argue that this may be a signature of spinodal decomposition in liquid crystals.|
|Keywords:||block copolymer,depolarized light scattering,order-disorder phase transition,small angle x-ray scattering,spinodal decomposition|
|Research Areas:||Polymers, Characterization|