The crystal orientation of poly(ε-caprolactone) (PCL) homopolymers, spatially confined in cylindrical nanodomains surrounded by polystyrene (PS) matrices, has been investigated as a function of crystallization temperature T c (−60 °C ≤ T c ≤ −40 °C) using two-dimensional small-angle X-ray scattering (2D-SAXS) and wide-angle X-ray diffraction (2D-WAXD). The sample was prepared by microphase separation of an PCL-block-PS copolymer followed by photocleavage at the block junction between PCL and PS blocks. The results were compared with crystal orientation of PCL blocks before photocleavage, i.e., PCL chains with one chain-end tethered at the cylinder interface. The lamellar crystals of PCL homopolymers and PCL blocks were preferentially oriented in cylindrical nanodomains irrespective of T c, i.e., the b axis of crystal unit cells was oriented parallel to the long axis of cylinders. The degree of crystal orientation increased remarkably with increasing T c for PCL homopolymers, whereas it improved slightly for PCL blocks, yielding a large difference in the degree of crystal orientation between two systems at higher T c (≥−45 °C).

The crystallization behavior and crystal orientation of poly(ε-caprolactone) (PCL) homopolymers and PCL blocks spatially confined in identical nanocylinders have been investigated using differential scanning calorimetry (DSC) and two-dimensional wide-angle X-ray diffraction (WAXD) as a function of cylinder diameter D. The PCL homopolymers confined in nanocylinders were prepared using microphase separation of PCL-block-polystyrene (PCL-b-PS) copolymers with a photocleavable o-nitrobenzyl group (ONB) between PCL and PS blocks and the subsequent cleavage of ONB by irradiating UV light. The time evolution of PCL crystallinity χ PCL showed a first-order kinetics for both PCL blocks and PCL homopolymers confined in all the nanocylinders investigated. However, the D dependence of crystallization rates for PCL blocks was more drastic than that for PCL homopolymers, and consequently various Ddependent interrelations were observed between crystallization rates of PCL blocks and PCL homopolymers. The crystal orientation was also dependent on D; the b-axis of PCL crystals oriented parallel to the cylinder axis both for PCL blocks and PCL homopolymers confined in the nanocylinder with D = 13.0 nm, whereas the (110) plane of PCL crystals was normal to the cylinder axis in the nanocylinders with D ≥ 14.9 nm. The difference in the degree of crystal orientation was not detected between PCL blocks and PCL homopolymers confined in nanocylinders with D ≥ 14.9 nm.