PolyCOFs: A New Class of Freestanding Responsive Covalent Organic Framework Membranes with High Mechanical Performance

Abstract

Traditional covalent organic frameworks (COFs) are prepared via polymerization based on small molecular monomers. However, the employment of polymers as building blocks to construct COFs has not been reported yet. Herein, we create a new concept of polymer covalent organic frameworks (polyCOFs) formed by linear polymers as structural building blocks, which inherit the merits from both COFs and linear polymers. PolyCOFs represent a new category of porous COF materials that demonstrate good crystallinity and high stability. More importantly, benefiting from the flexibility and processability of a linear polymer, polyCOFs can spontaneously form defect-free, flexible, and freestanding membranes that exhibit excellent mechanical properties and undergo reversible mechanical transformation upon exposure to various organic vapors. For the first time, we demonstrated that polyCOF membranes can be used as artificial muscles to perform various complicated motions (e.g., lifting objects, doing “sit-ups”) triggered by vapors. This study bridges the gap between one-dimensional amorphous linear polymers and crystalline polymer frameworks and paves a new avenue to prepare stimuli-responsive actuators using porous COF materials.

Combined Intrinsic and Extrinsic Proton Conduction in Robust Covalent Organic Frameworks for Hydrogen Fuel Cell Applications

“…These advantages render COFs a promising platform for proton conductivity and PEMs. Recently, significant progress has been made by Dichtel, Banerjee, our group, and others to fabricate high‐performance COF membranes. The Banerjee group achieved a benchmark proton conductivity (7.8×10 −2 S cm −1 ) for a freestanding COF membrane that further served as the PEM of a membrane electrode assembly (MEA) and delivered the highest power output (maximum 24 mW cm −2 ) among all reported COFs .…”

Polymer Networks: From Plastics and Gels to Porous Frameworks

“…Thed evelopment of new reaction methodologies and advanced (macro)molecular architectures and topologies will further fuel the design of polymer networks with fascinating behaviors [275][276][277][278] and improved mechanical properties.I n addition, practical, scalable synthetic strategies are necessary to meet the existential need for sustainable polymer networks, [279,280] next-generation energy storage/harvesting materials,separations membranes,and catalysts.Finally,new tools for the generation of polymer network databases amenable to advanced computational screening and machine learning are highly sought after. [281] Thus,t here is no doubt that this field will continue to witness exciting progress for the foreseeable future.…”

Emerging porous nanosheets: From fundamental synthesis to promising applications

“…Inspired by this, nanosheets materials may be prepared by this method. Specifically, building blocks are restricted and reacted in the confined interface region to modulate the growth direction of MOFs and COFs, leading to the formation of MOF and COF nanosheets at the interface [69][70][71][72][73][74][75]. Notably, choosing suitable solvents or substrates to build the interfacial growth environment remains one of the key factors in this method.…”