Abstract
We reexamine the stability of hexagonally modulated layer (HML) and hexagonally perforated layer (HPL) morphologies in a number of block copolymer systems of low to moderate molecular weight. Using small-angle X-ray scattering and dynamic mechanical spectroscopy, we show that these structures are long-lived nonequilibrium states which convert to the bicontinuous gyroid (G) morphology upon isothermal annealing. Comparison of phase transition kinetics across chemically distinct systems spanning a wide range of molecular weights and monomeric friction coefficients reveals a composition dependence to these dynamics. This suggests effects associated with the mobility of individual chains are of lesser importance in explaining the apparent metastability of the HML and HPL structures: instead, the composition dependence of the transition mechanism appears to dominate the observed behavior. The revised phase behavior for these materials is in excellent agreement with mean-field predictions for diblock copolymer melts.
Original language | English |
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Journal | Macromolecules |
Volume | 30 |
Issue number | 13 |
Pages (from-to) | 3788-3795 |
ISSN | 0024-9297 |
DOIs | |
Publication status | Published - 1997 |