Segmented copolymers with monodisperse crystallizable hard segments: novel semi-crystalline materials

Segmented block copolymers with short monodisperse crystallizable hard segments have interesting structures and properties. In the melt, such short monodisperse segments are miscible with the matrix segments. Moreover, upon cooling, they crystallize fast, demonstrating a very high crystallinity, and only a small crystallization window is needed. The melting temperature of the short segments is high, provided that they can H-bond and/or contain aromatic groups. The melting temperature was found to decrease with increasing matrix segment concentration, due to the solvent effect of the matrix segments. At concentrations of crystallizable segment of 4–35 wt%, good dimensional and solvent stabilities were obtained. The monodisperse segments crystallized into nano-ribbons with uniform thickness and high aspect ratio, and these dispersed nano-ribbon crystallites constituted physical crosslinks, while acting also as reinforcing fillers. At concentrations of the monodisperse segments below 20 wt% no spherulitic ordering took place, and the semi-crystalline polymers were transparent. The monodisperse crystallizable segments can be used in combination with matrix segments of either low or high glass transition temperature, and may even contain (bio)functional units.