Mesoporous Phenolic/POSS Hybrids Induced by Microphase Separation Arising from Competitive Hydrogen Bonding Interactions

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.

Organic‐Inorganic Phenolic/POSS Hybrids Provide Highly Ordered Mesoporous Structures Templated by High Thermal Stability of PS‐b‐P4VP Diblock Copolymer

“…Phenyltrimethoxysilane, methyl dichlorosilane, sodium hydroxide (NaOH), CH 2 O, nadic anhydride, paraformaldehyde (CH 2 O), phenol, and 4‐aminophenol were acquired from Sigma‐Aldrich. Phenolic/DDSQ (PDDSQ) hybrid with 30 wt.% DDSQ weight fraction was synthesized through phenol and DDSQ−4OH, which was described previously as shown in Scheme 1(b) [54–56] …”

“…Phenolic/DDSQ (PDDSQ) hybrid with 30 wt.% DDSQ weight fraction was synthesized through phenol and DDSQÀ 4OH, which was described previously as shown in Scheme 1(b). [54][55][56] The preparation of PPDSQ/PS-b-P4VP blends and mesoporous PDDSQ hybrids PS-b-P4VP with various concentrations of PDDSQ-30 were separately stirred in THF solution at 25 °C for 24 h, and these solutions were poured into an aluminum plate, sealed with aluminum foil, and slowly evaporated based on the evaporation-induced selfassembly mechanism at 40 °C for 2 days. After drying out the THF solution, the samples were placed in an oven for thermal polymer- Chemistry-A European Journal ization at 180 °C for 24 h, and self-assembled structures of the PDDSQ/PS-b-P4VP hybrids were achieved.…”

“…Since the DDSQ cage structure could provide a protected inorganic layer, the thermal decomposition temperature, and char yield could be extensively improved to 532 °C and 70.4 wt.% [54] . As a result, various mesoporous phenolic PDDSQ hybrids can be prepared templated by PEO‐ b ‐PCL, including cylindrical, spherical, double gyroid, and even Frank‐Kasper structures [55–57] . In this study, using a PS‐ b ‐P4VP diblock copolymer as a template, highly ordered mesoporous phenolic materials containing DDSQ hybrids was constructed.…”

“…Incorporating inorganic materials into phenolic resins could be considered a simple way to achieve this goal. [47][48][49][50][51] In our previous studies, [52][53][54][55][56][57][58] we synthesized various compositions of double-decker silsesquioxane (DDSQ) into the phenolic resin to form phenolic/DDSQ hybrids (PDDSQ), and the thermal decomposition temperature was increased substantially with an increase in DDSQ concentration. Since the DDSQ cage structure could provide a protected inorganic layer, the thermal decomposition temperature, and char yield could be extensively improved to 532 °C and 70.4 wt.%.…”

Construction of Fluorescent Conjugated Polytriazole Containing Double-Decker Silsesquioxane: Click Polymerization and Thermal Stability

“…The polyhedron structures include complete cage and partial cage structures [ 11 , 12 , 13 , 14 , 15 , 16 , 17 , 18 , 19 , 20 ]. Polyhedral oligomeric silsesquioxane (POSS) as an inorganic cage structure in the polymer matrix could improve the thermal, mechanical, surface, and dielectric properties that have been widely investigated during the last two decades [ 21 , 22 , 23 , 24 , 25 ] because of its high molecular weight and three-dimensional structure that could reduce the possibility of molecular stacking and even crystallization. Our previous studies have proposed the polymer matrix’s non-functional, mono-functional, di-functional, and multi-functional POSS cage structures [ 15 ].…”