Polymer crystallization in 25-nm spheres

Crystallization within the discrete spheres of a block copolymer mesophase was studied by time-resolved x-ray scattering. The cubic packing of microdo mains, established by self-assembly in the melt, is preserved throughout cr ystallization by strong interblock segregation even though the amorphous ma trix block is well above its glass transition temperature. Homogeneous nucl eation within each sphere yields isothermal crystallizations which follow f irst-order kinetics, contrasting with the sigmoidal kinetics normally exhib ited in the quiescent crystallization of bulk polymers.