Mesoporous Phenolic/POSS Hybrids Induced by Microphase Separation Arising from Competitive Hydrogen Bonding Interactions
Yen‐Chi Huang, Wei‐Cheng Chen, Shiao‐Wei Kuo
Abstract
We used ring-opening living polymerization to synthesize various linear poly(ethylene oxide–b–caprolactone) (PEO-b-PCL, EC) diblock copolymers featuring PCL blocks of various molecular weights and prepared phenolic resins with various double-decker silsesquioxane (DDSQ) cage compositions in the form of phenolic/DDSQ (PDDSQ) hybrids. Upon forming PDDSQ/EC blends, competitive hydrogen bonding of the phenolic OH units of PDDSQ occurred with both ether units of the PEO block and C═O units of the PCL block, with the fraction of hydrogen-bonded C═O groups increasing upon increasing the PDDSQ compositions but decreasing upon increasing the molecular weight of the PCL block in EC diblock copolymers. Small-angle X-ray scattering revealed the self-assembled structures and corresponding phase diagram of these PDDSQ/EC blends after thermal polymerization at 150 °C, with the d-spacing increasing upon increasing the molecular weight of PCL block in the EC diblock copolymers. After removal of the EC diblock copolymer template, we obtained mesoporous phenolic/DDSQ hybrids possessing high surface areas and pore volumes, with the highly ordered mesoporous structures featuring double-gyroid, hexagonal-packing cylindrical, spherical, and even Frank–Kasper (FK) structures depending on the molecular weight of PCL block and the content of the PPDSQ hybrid. Overall, this study provides a general principle for obtaining mesoporous double-gyroid and FK phases mediated by diblock copolymer compositions through competitive hydrogen-bonding interactions.