Pressure-Induced Polymerization: Addition and Condensation Reactions

Under pressure of 1–100 GPa, unsaturated organic molecules tend to form covalent bond to each other for a negative enthalpy change, which often produces polymeric materials with extended carbon skeleton. The polymerization reactions typically happen in crystal, which promotes the topochemical process. This review summarized the topochemical polymerization processes of several alkynes, aromatics, and alkynylphenyl compounds, including the critical crystal structures before the reaction, bonding process, and the structure of the products. Secondly, this review also summarized the condensation reaction identified in the polymerization process, including the elimination of small molecules such as NH3, etc.

Solution-processable and functionalizable ultra-high molecular weight polymers via topochemical synthesis

Topochemical polymerization reactions hold the promise of producing ultra-high molecular weight crystalline polymers. However, the totality of topochemical polymerization reactions has failed to produce ultra-high molecular weight polymers that are both soluble and display variable functionality, which are restrained by the crystal-packing and reactivity requirements on their respective monomers in the solid state. Herein, we demonstrate the topochemical polymerization reaction of a family of para-azaquinodimethane compounds that undergo facile visible light and thermally initiated polymerization in the solid state, allowing for the first determination of a topochemical polymer crystal structure resolved via the cryoelectron microscopy technique of microcrystal electron diffraction. The topochemical polymerization reaction also displays excellent functional group tolerance, accommodating both solubilizing side chains and reactive groups that allow for post-polymerization functionalization. The thus-produced soluble ultra-high molecular weight polymers display superior capacitive energy storage properties. This study overcomes several synthetic and characterization challenges amongst topochemical polymerization reactions, representing a critical step toward their broader application.

Reversible Topochemical Polymerization and Depolymerization of a Crystalline Three-Dimensional Porous Organic Polymer with C–C Bond Linkages

Three-dimensionally connected porous organic polymers are of interest because of their potential in adsorption, separation, and sensing, among others. When crystalline, they also afford accurate structure description, which in turn can enable particular functions. However, crystallization of three-dimensional (3D) polymers is challenging. This is especially true when targeting polymerization via stable C–C bonds, whose formation is usually irreversible and does not allow for error correction typically required for crystallization. Here, we report polyMTBA, the first 3D-connected crystalline organic polymer with permanent porosity, here formed via C–C linkages. High crystallinity is achieved by solid-state topochemical reaction within monomer MTBA crystals. polyMTBA is recyclable via thermal depolymerization and is solution-processable via its soluble monomers. These results reveal topochemical polymerization as a compelling methodology for generating stable, crystalline, and porous 3D organic frameworks.

Reversible Topochemical Polymerization and Depolymerization of a Crystalline Three-Dimensional Porous Organic Polymer with C–C Bond Linkages

Three-dimensionally connected porous organic polymers are of interest because of their potential in adsorption, separation, and sensing, among others. When crystalline, they also afford accurate structure description, which in turn can enable particular functions. However, crystallization of three-dimensional (3D) polymers is challenging. This is especially true when targeting polymerization via stable C–C bonds, whose formation is usually irreversible and does not allow for error correction typically required for crystallization. Here, we report polyMTBA, the first 3D-connected crystalline organic polymer with permanent porosity, here formed via C–C linkages. High crystallinity is achieved by solid-state topochemical reaction within monomer MTBA crystals. polyMTBA is recyclable via thermal depolymerization and is solution-processable via its soluble monomers. These results reveal topochemical polymerization as a compelling methodology for generating stable, crystalline, and porous 3D organic frameworks.

Pressure induced topochemical polymerization of solid acrylamide facilitated by anisotropic response of the hydrogen bond network

Our first-principles studies reveal the mechanism of pressure-induced polymerization in solid acrylamide. Pressure not only drives a topochemical mechanism but also lowers the polymerization barrier at room temperature.

Polymers with advanced structural and supramolecular features through topochemical polymerization

Polymers are an integral part of our daily life. Hence, there are constant efforts towards synthesizing novel polymers with unique properties. As the composition and packing of polymer chains influence...