We report the preparation of hierarchically porous polymers containing fully interconnected and controlled micro-, meso-, and macropores, where a hyper-cross-linked microporous polymer skeleton forms a reticulating mesoporous wall that supports a highly porous macropore framework. These materials provide high specific surface area and >90% porosity, useful for rapid sorption of organic molecules.

This image from the research of Soobin Kim and Myungeun Seo on page 900 shows a scanning electron micrograph of a hierarchically porous polymer synthesized by combination of hyper‐crosslinking with polymerization‐induced microphase separation (PIMS). Three‐dimensionally continuous mesopores with size of ca. 10 nm are evident. The PIMS process allows them to readily produce a crosslinked block polymer precursor with a disordered bicontinuous morphology composed of polylactide (PLA) and polystyrenic microdomains. A hyper‐crosslinking reaction degrades the PLA to generate the mesoporous space, and it simultaneously creates micropores smaller than 2 nm (not visible) within the polystyrenic microdomain to yield the hierarchical pore structure. This provides improved stability and accelerated diffusion to microporous surface. (DOI: 10.1002/pola.28966)

Microcapsules with nanoporous membranes can regulate transmembrane transport in a size-dependent fashion while protecting active materials in the core from the surrounding, and are thereby useful as artificial cell models, carriers for cells and catalysts, and microsensors. In this work, we report a pragmatic microfluidic approach to producing such semipermeable microcapsules with precise control of the cutoff threshold of permeation. Using a homogeneous polymerization mixture for the polymerization-induced microphase separation (PIMS) process as the oil phase of water-in-oil-in-water (W/O/W) double emulsions, a densely cross-linked shell composed of a bicontinuous nanostructure that percolates through the entire thickness is prepared, which serves as a template for a monolithic nanoporous membrane of microcapsules with size-selective permeability. We demonstrate that the nanopores with precisely controlled size by the block polymer self-assembly govern molecular diffusion through the membrane and render manipulation of the cutoff threshold.

We report synthesis of hierarchically porous polymers (HPPs) consisting of micropores and well-defined 3D continuous mesopores by combination of hyper-cross-linking and block polymer self-assembly. Copolymerization of 4-vinylbenzyl chloride (VBzCl) with divinylbenzene (DVB) in the presence of polylactide (PLA) macro-chain-transfer agent produced a cross-linked block polymer precursor PLA-b-P(VBzCl-co-DVB) via reversible addition–fragmentation chain transfer polymerization. A nanoscopic bicontinuous morphology containing PLA and P(VBzCl-co-DVB) microdomains was obtained as a result of polymerization-induced microphase separation. While a basic treatment of the precursor selectively removed PLA to yield a reticulated mesoporous polymer, hyper-cross-linking of the precursor by FeCl3 generated micropores in the P(VBzCl-co-DVB) microdomain via Friedel–Crafts alkylation and simultaneously degraded PLA to produce the HPP containing micropores in the mesoporous framework. The mesopore size of the HPP could be precisely controlled from 6 to 15 nm by controlling the molar mass of PLA. We demonstrate acceleration in adsorption rate in the HPP compared to a hyper-cross-linked microporous polymer.