Direct Polymerization of Carbon Dioxide, Diynes, and Alkyl Dihalides under Mild Reaction Conditions

Fixing carbon dioxide (CO2) into useful polymeric materials has attracted broad interest since carbon dioxide is an abundant, inexpensive, nontoxic, and renewable Cl resource. Nevertheless, the polymerization of CO2 and alkynes attracted less attention because the propagation step involving CO2 is a major obstacle. Herein, we overcome this obstacle by developing a facile and efficient Ag2WO4-catalyzed polymerization of CO2, diynes, and alkyl dihalides under mild reaction conditions. Soluble and thermally stable poly(alkynoate)s with high weight-average molecular weights (up to 31 400) were obtained in high yields (up to 95%). Thanks to its unique reaction mechanism, this step-growth polymerization can produce an ethynyl group terminated telechelic polymer that can be used as macromonomer to prepare poly(alkynoate)s with higher molecular weights by either continually adding alkyl dihalide into the reaction solution or mixing the isolated telechelic polymers with alkyl dihalide and catalytic system under a CO2 atmosphere. The resultant polymers show versatile properties. The tetraphenylethene, silole, and tetraphenylpyrazine moieties that feature the aggregation-induced emission (AIE) characteristics can be facilely incorporated into the polymer main chains to make them AlE active with high absolute quantum yields up to 61% in the film state. Their containing ester linkages endow the polymers degradable under basic conditions, and the alkynoate repeating units enable them to be postfunctionalized by the powerful amino-yne click reaction to generate nitrogen-containing stereo- and regioregular polymers with unity grafting ratio. Thus, this work not only establishes a powerful polymerization to directly fix CO2 but also provides poly(alkynoate)s with versatile properties.