Phase-separated structures of random methacrylate copolymers with pendant POSS moieties

The phase separation of random methacrylate copolymers with the pendant polyhedral oligomeric silsesquioxanes (POSS) moieties was studied. For the random copolymers of the phenyl-substituted POSS methacrylate (PhPOSSMA) and butyl methacrylate (BMA), the layer-like phase-separated structures were obtained from the copolymers with over circa 20 wt % of PhPOSSMA after thermal annealing in the bulk. The copolymers with larger PhPOSSMA content over 40 wt % showed periodic phase-separated structure with the periodic length ranging from 9.0 to 5.1 nm depending on the composition. The phase separation did not occur by solvent annealing in the bulk. On the other hand, no phase-separated structure was formed from the random copolymer with circa 50 wt % of isobutyl-substituted POSSMA (i-BuPOSSMA) and BMA after thermal annealing. In addition, the phase separation did not occur for both of the random copolymers of PhPOSSMA and i-BuPOSSMA with methyl methacrylate. The resulting phase-separated structures were well characterized by using wide-angle X-ray scattering, small-angle X-ray scattering, and transmission electron microscopy image. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 47246.