Porous polymers can be classified into three classes based on their pore size ranging from micro- (&lt; 2 nm), meso- (2 - 50 nm) and macropore (&gt; 50 nm). Hierarchically porous polymers containing interconnected pores across multiple length scales are desirable for applications where high surface area as well as efficient transport within the porous space is important. To make such materials, different pore generation methodologies should be adequately combined to achieve orthogonal control over pore size and porosity at different length scales ranging from angstroms to micrometers. We report a methodology to construct HPPs containing micropores within the mesoporous framework by combining hyper-cross-linking with block copolymer self-assembly. Hyper-cross-linking has been a well-known strategy for synthesis of microporous polymers. Typically, lightly cross-linked polystyrenic precursors such as poly(vinylbenzyl chloride-co-divinylbenzene) are synthesized and reacted with FeCl3 in the swollen state with 1,2-dichloroethane. Friedel-Crafts alkylation connects the aromatic rings via methylene bridge formation, which firmly arrests free volume between the polymer chains to form permanent micropores of ca. 1 nm. High specific surface area up to 2000 m2 g-1 and synthetic feasibility of the precursors via radical polymerization render hyper-cross-linking suitable particularly for synthesis of hierarchically porous polymers in combination with block copolymer self-assembly. In this talk, I will discuss our recent efforts on synthesis of hierarchically porous polymers by hyper-cross-linking of block copolymer precursors. By utilizing polylactide (PLA)-b-polystyrenic block copolymers which template well-defined mesoporous polymers by selective removal of PLA, I will show that hyper-cross-linking can successfully generate micropores within the polystyrenic microdomain and also reinforce it to firmly support the mesoporous space. I will also demonstrate facilitated diffusion in hierarchically porous polymers and acceleration in adsorption rate of target substances.

Hierarchically porous polymers via hyper-cross-linking of block copolymer precursors

256th National Meeting (2018)

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