Direct heteroarylation polymerization of a π-conjugated polymer with degradable 1,2,4-oxadiazole linkers

Abstract

The synthesis of π-conjugated polymers containing a degradable 1,2,4-oxadiazole linker by direct heteroaryl polymerization (DHAP) is reported.

Thienoisoindigo-based recyclable conjugated polymers for organic electronics

“…S6, and Table S1†), a method that is commonly used to determine the molecular weight of many acid-degradable polymers. 34,37–41 The M n values for p(TII-PD) and p(TII-2,6ND) were 22.3 kDa and 19.2 kDa, respectively, with dispersity values in the typical range for poly(azomethine)s synthesized via imine polycondensation reactions. 58 Thermogravimetric analysis (TGA) results shown in Fig.…”

“…[28][29][30] Significant efforts have gone into synthesizing new degradable semiconducting polymers for applications in transient electronics [31][32][33] using cleavable moieties such as imines, [34][35][36] imidazoles, 37,38 alkynes 39 or oxadiazoles. 40 However, limited reports on the chemical recyclability of semiconducting polymers exist because it remains a challenge to design π-conjugated polymers that can degrade into stable by-products.…”

Degradable π-Conjugated Polymers

“…Phosphine-free conditions resulted in moderately higher polymerization yields with higher molecular weights compared to those of the β-branching suppression conditions. Interestingly, the authors suggest that the relatively high free energy of activation for the monomers, coupled with the lower temperature and sterically bulky reagents used in the β-branching-suppressing conditions, may be responsible for slowing the polymerization enough for debromination to outcompete and hinder the polymerization of the β-branching-suppressing conditions . More recently, Tran and co-workers have recently demonstrated the first example of a successful optimization of DArP for the synthesis of a degradable imine-based conjugated polymer.…”

“…We have previously highlighted select examples which utilize the imine bond ,,− in the backbone as a cleavable site that maintains π-conjugation (Figure a). However, many other degradable linkers which maintain π-conjugation along the polymer backbone may be used such as imidazoles, oxadiazoles, or simple alkene linkages. These linkers are notably cleaved through chemical, UV, or enzymatic degradation.…”

“…This shed light on the importance of monomeric design when using DArP as a coupling strategy for degradable polymers. In 2022, Seferos and co-workers 77 synthesized a new class of degradable π-conjugated polymers using oxadiazole as the cleavable π-conjugated monomer via DArP (Figure 4h). In their approach, an asymmetric monomer was synthesized flanking the 1,2,4-oxadiazole linker between two thiophene groups.…”