Evolution of Microstructure in the Liquid and Crystal Directions in a Quenched Block Copolymer Melt and Its Implication on Phase Transition Mechanisms

Published

November 1, 1998

Author(s)

N P. Balsara, B A. Garetz, M C. Newstein, Barry J. Bauer, T J. Prosa

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.

Citation

Macromolecules

Volume

31

Issue

No. 22

Pub Type

Journals

Keywords

block copolymer, depolarized light scattering, order-disorder phase transition, small angle x-ray scattering, spinodal decomposition

Citation

Balsara, N. , Garetz, B. , Newstein, M. , Bauer, B. and Prosa, T. (1998), Evolution of Microstructure in the Liquid and Crystal Directions in a Quenched Block Copolymer Melt and Its Implication on Phase Transition Mechanisms, Macromolecules (Accessed July 23, 2024)