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.

We report on the use of photoinitiated reversible addition–fragmentation chain transfer (RAFT) polymerization for the facile fabrication of cross-linked nanoporous polymer films with three-dimensionally (3D) continuous pore structure. The photoinitiated polymerization of isobornyl acrylate (IBA) in the presence of 2-(dodecylthiocarbonothioylthio)-2-methylpropionic acid (CTA) and 2,2-dimethoxy-2-phenylacetophenone as a photoinitiator proceeded in a controlled manner, yet more rapidly compared to thermally initiated polymerization. When polylactide-macroCTA (PLA-CTA) was used, PLA-b-PIBA with high molar mass was obtained after several minutes of irradiation at room temperature. We confirmed that microphase separation occurs in the PLA-b-PIBA and that nanoporous PIBA can be derived from the PLA-b-PIBA precursor by selective PLA etching. To fabricate the cross-linked nanoporous polymer, IBA was copolymerized with ethylene glycol diacrylate (EGDA) in the presence of PLA-CTA to produce a cross-linked block polymer precursor consisting of bicontinuous PLA and P­(IBA-co-EGDA) microdomains, via polymerization-induced microphase separation. We demonstrated that nanoporous P­(IBA-co-EGDA) monoliths and films with 3D continuous pores can be readily obtained via this approach.

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.

Mesoporous nonoxide ceramics are attractive for applications such as catalytic supporters and separations with exceptional thermochemical stability. Here we report on the one-step preparation of microphase-separated bicontinuous organic–inorganic polymer precursors for forming 3D continuous polymer-derived ceramic monoliths without an external block copolymer template and annealing steps. We combined polymerization-induced phase separation with in situ hybrid block polymer formation from a mixture of a preceramic monomer, a cross-linker, and a thermally decomposable organic segment containing a terminal chain transfer agent. The resultant cross-linked polymeric monoliths, moldable to any desired shape, were converted to 3D-continuous mesoporous silicon carbonitride ceramics with a pore size in the 3–11 nm range and a surface area of 107–410 m2 g–1 by varying the molar mass of the sacrificial organic block and the pyrolytic temperature. The 3D-disordered pore structure is beneficial for retaining the monolithic shape via isotropic shrinkage during ceramization. The distinctive characteristics of this synthetic approach, which are the absence of a solvent, a structure-directing block copolymer, and an annealing process, are affordable for the large production of nanoporous ceramic monoliths for various high-temperature applications and should be applicable for additive manufacturing with direct polymerizability for the fabrication of hierarchically porous materials in complex shapes with dimensional scalability.

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