Unexploited Design and Application of Dynamic Covalent Networks: Phenol-yne Click Reaction and Porous Film Generation

Abstract

Dynamic covalent networks (DCNs) have attracted great attention because of their capacity for reprocessing and remolding, based on macromolecular architecture transformations or rearrangements through dynamic exchange reactions. Here, a new dynamic exchange reaction between a phenol and an enol-one motif yielded from the phenol-yne click reaction is introduced, and the phenol-yne click reaction is facilely integrated into the fabrication of a novel DCN. To expand the scope of material recycling, another degradable DCN prepared using the same click reaction but with a degradable diacetal motif is introduced. After thermal fusion of these two DCNs and subsequent acidic hydrolysis, a porous polymer film with a porosity of 46% is afforded, which is verified to possess excellent oil absorption capacity and recyclability. The strategic design and fabrication of porous polymer films provide an entirely new pathway for the application of DCNs.

Recyclable, Degradable, and Fully Bio-Based Covalent Adaptable Polymer Networks Enabled by a Dynamic Diacetal Motif

“…Hence, recyclable materials that are simultaneously degradable would be more desirable in the context of being applied to commodity products. 7−10 In constructing recyclable network materials, dynamic covalent bonds are generally incorporated into the polymer strands, and to date, various kinds of dynamic motifs have been reported, including Diels−Alder adducts, 11 ester, 12 thioester, 13 silyl ether, 14 boronic ester, 15 amide-imide, 16 enamine, 17,18 enol, 19 and so forth. However, most dynamic motifs generally are not degradable.…”

X‐yne click polymerization

“…Reproduced with permission: Copyright 2022, American Chemical Society. [158] advantage of this fascinating dynamic nature of enamine bonds, Lin and coworkers designed and prepared a vitrimer by amino-yne click polymerization. [155] Compared with the referenced vitrimer BPAE-ATH produced by amineacetoacetate condensation, the resultant vitrimer network BPAE-PTH showed a faster dynamic exchange as verified by Arrhenius analysis, and possessed superior mechanical properties, which was attributed to the absence of byproducts such as water molecules, thus reducing the network defects.…”

“…[ 157 ] Almost at the same time, Lin and coworkers also found this new dynamic exchange reaction and integrated it into the construction of reprocessable dynamic covalent network of BPA‐TH. [ 158 ] By further introducing a degradable network of VPV‐TH containing diacetal motifs into BPA‐TH by hot press and utilizing the selective hydrolysis of acetal motifs under acidic conditions, functional porous polymer film with a porosity of 46% was fabricated (Figure 6C). These works demonstrate the great potential of X‐yne click polymerization in the field of functional dynamic materials.…”

Dynamic covalent polymers generated from X‐yne click polymerization

“…The X-yne adducts have successively been proved to be "dynamic" under external stimuli. 28,29,[47][48][49] As shown in Scheme 1, there are three dynamic exchange processes found in the products of X-yne click polymerization under the promotion of base catalyst or in a spontaneous fashion. When extra nucleophilic reagents are added into the reaction system, dynamic exchange will occur through the formation of β-heteroatom enolate intermediate and eventually reach an equilibrium.…”

“…47 Based on this, the degradation of linear polymers under mild conditions has been realized through dynamic amine exchange, 28,29 and several dynamic covalent polymer networks prepared by X-yne click polymerization have been successfully applied in the fields of CANs (including vitrimers), [50][51][52][53] self-healing injectable hydrogels 54 and functional porous materials. 49 While this branch of X-yne click polymerization is still in its infancy, the combination of "click" and "dynamic" characteristics makes X-yne click polymerization a promising candidate in the field of dynamic covalent chemistry, which can not only provide highly efficient synthetic methodologies, but also introduce new dynamic structures, thus breathing new life into this field. This is why we chose to write this review at this…”