Crystallization Behavior of Poly(ε-caprolactone) Chains Confined in Nanocylinders: Effects of Block Chains Tethered to Nanocylinder Interfaces

Abstract

The crystallization behavior of poly(e-caprolactone) (PCL) chains (i.e., PCL block + PCL homopolymer systems) spatially confined in nanocylinders with different diameters D has been investigated as a function of the mole fraction of PCL homopolymers fhomo existing in the PCL chains. The nanocylinders with PCL chains inside were prepared using the microphase separation of PCL-block-polystyrene (PCL-b-PS) diblock copolymers with a photocleavable o-nitrobenzyl group (ONB) between PCL and PS blocks, and subsequently ONB was cleaved by a controlled irradiation of UV light to get the PCL chains with various fhomo. In the isothermal crystallization process, the crystallinity of PCL chains showed an exponential time evolution (or first-order kinetics) for all the systems investigated. The half-time of crystallization of PCL chains with 0 < fhomo < 1 was found to be intermediate between those of PCL blocks (fhomo = 0) and PCL homopolymers (fhomo ∼ 1); it decreased moderately with increasing fhomo in a smaller nano...