On the crystallization behavior of a poly(stearyl methacrylate) comb-like polymer inside a nanoscale environment

Abstract

Using a composite “hard” and “soft” template, approached by a macroscopic polystyrene (PS) matrix and a microscopic coaxial nanofiber, the crystallization of poly(stearyl methacrylate) (PSMA), a comb-like polymer under nanoscale conditions was explored. Crystalline structures and morphologies of a polyethylene terephthalate (PET)/PSMA nanofiber (NF) and PET/PSMA@PS composite membrane (CM) were characterized by differential scanning calorimetry, scanning electron microscopy, and transmission electron microscopy. Regulated by an orientated PET NF shell and PS matrix, the PSMA inner core showed a nanosize-dependent crystallization phenomenon. A “hard” or “soft” condition was approached by controlling the annealing temperature below 60 °C or above 120 °C, respectively. Confined crystallization in the entrapped PSMA was demonstrated, and PET/PSMA@PS CM showed a longer half-time of crystallization (t_1/2 = 1.69) than that of PET/PSMA NF (t_1/2 = 1.14). Therefore, against bulk PSMA (t_1/2 = 0.61), the increased crystallization time under nanoscale conditions was attributed to the reduced chain relaxation and mobility of alkyl groups.