Lamellar ordering and crystallization in a symmetric block copolymer

By using time-resolved small-angle x-ray scattering, the crystallization and melting behavior in an ordered lamellar morphology has been investigated for a symmetric short-chain poly(ethylene oxide)-b-butadiene (PEO-b-PBh) block copolymer. The long period of the crystallized lamella continuously increases with the crystallization temperature, and no integer number of stems can be assigned to the folded chain crystals. The effects of deviations of the poly(ethylene oxide) (PEO) and PB chains from a Gaussian coil in the ordered phase on the PEO crystallization are evaluated and modeled. Samples cooled fast from different temperatures in the molten state reveal a significant coupling between lamellar ordering and crystallization. The reorganization of the chains during cooling promotes nucleation and shortens the induction period.

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