Main Chain 1,5-Disubstituted-1 H -Tetrazole-Based Polymers via Ugi-Azide-Four-Multicomponent Polymerization (UA-4MCP)

Abstract

The utilization of the distinctive molecular architecture of tetrazoles, which comprises a five-membered ring containing four nitrogen atoms, offers tremendous potential in the field of polymer chemistry. Although research on pendant chain tetrazole-containing polymers has been considerably reported, the exploration of advanced synthesis methods for main chain tetrazole-based polymers has not been extensively undertaken. On this premise, the synthesis of main chain 1,5-disubstituted-1H-tetrazole (1,5-DS-T)-based compounds was investigated to showcase the possibility of polymer formation by using the Ugi-azide-four-multicomponent polymerization (UA-4MCP) strategy. Particularly, UA-4MC polymers were designed with various side groups (e.g., aliphatic or aromatic) and engineered for a post-polymerization modification via thiol-ene photo-click reaction. The chemical characterization confirmed 1,5-DS-T-based polymer formation with a number average molecular mass (Mn) up to 8500 g mol–1. Importantly, side-group variation permitted tuning the glass-transition temperature (Tg) between −25 and 60 °C. Furthermore, the polymers exhibited moderate thermal stability up to 305 ± 10 °C besides interesting nonconventional fluorescence behavior.