Construction of membrane reactors coupled with conjugated network hollow microspheres for cascade production of block copolymers

Membrane reactors have inspired a cascading and sustainable approach toward chemical production and processing, offering potential for improving reaction efficiency and addressing limitations to product purification. In this work, hollow microspheres comprising porphyrinic conjugated microporous networks (H-PPrIB-M MSs) are engineered through Sonogashira-Hagihara cross-coupling polycondensation with the assistance of silica templates. Using the photoinduced electron/energy transfer-reversible addition-fragmentation chain transfer (PET-RAFT) polymerization with H-PPrIB-M MSs as heterogeneous catalysts, polymerization was conducted under mild conditions: low-intensity household white light or far-red light, closed or open reaction vessels, ambient temperature, and ultrapure water as the solvent. Taking advantage of the robustness of H-PPrIB-M MSs, the suspended catalysts were fitted into membrane reactors to fabricate the suspended-catalyst-based membrane reactor (SCBMR) system. High polymerization kinetics, oxygen tolerance and precise control over molecular weights and polydispersities were achieved in the SCBMR systems. Separation and reutilization of the catalyst-functionalized nanocomposite was realized through facile centrifugation, which led to negligible catalyst leaching and maintenance of catalytic performance over six polymerization cycles. The purification of PHEAA- b -PNAT- b -PHPGA-CDSP triblock copolymers with purity exceeding 99% could be accomplished within 2.1 diavolumes. With the concept of such catalytic membrane reactors, this work represents a simplified and customizable synthetic tool to unlock macromolecular buildups with precisely controlled architectures and desirable properties for a variety of high-value applications. We present a design for cascade polymer production by exploiting the construction of membrane reactors coupling with conjugated network hollow microspheres as suspended catalysts to combine aqueous photopolymerization and membrane separation process.