Multicomponent spiropolymerization of diisocyanides, alkynes and carbon dioxide for constructing 1,6-dioxospiro[4,4]nonane-3,8-diene as structural units under one-pot catalyst-free conditions

Carbon dioxide (CO2) is a greenhouse gas whose release should be reduced to as low as possible. However, using this gas is another method for reducing the greenhouse effect. In this work, a novel multicomponent spiropolymerization was developed by using diisocyanides, alkynes and CO2 based on catalyst-free one-pot polymerization under mild experimental conditions. A structural unit with 1,6-dioxospiro[4,4]nonane-3,8-diene as one of the main chains was instantly formed by converting CO2 into spirosegments, and these resultant spiropolymers had high weight-average molecular weights (Mws, up to 59 000) and good yields (up to 87.7%). In detail, the effect of the diisocyanide monomers on the Mws, yields and solubility of the resultant spiropolymers was investigated and discussed. The obtained spiropolymers showed excellent solubility and high thermal stability. Thus, a simple and high-atom-economical spiropolymerization for preparing new spiropolymers was established by taking full advantage of CO2 and resulted in a unique spiroarchitecture by catalyst-free one-pot polymerization, which provided new kinds of spiropolymers for the materials science field.