Gold-Catalyzed Post-Polymerization Modification of Commodity Aromatic Polymers.

Synthetic aromatic polymers are ubiquitous and indispensable to modern life, industry, and the global economy. The direct functionalization of these materials remains a considerable challenge on account of their unreactive aromatic C-H bonds and robust physical properties. Here, we demonstrate that homogeneous gold catalysis offers a mild, chemoselective, and practical approach to functionalize high-volume commodity aromatic polymers. Utilizing a gold-catalyzed intermolecular hydroarylation between a methyl ester functionalized alkyne, methyl propiolate, and nucleophilic arenes within polystyrene (PS) results in direct functionalization of phenyl rings with 1,2-substituted methyl acrylate functional groups. The reactivity and functionalization depend on the steric and electronic environment of the catalyst, counterion pairing, and method of activation. The reactivity is broad in scope, enabling the functionalization of arenes within commercial polysulfone (PSU) and waste polyethylene terephthalate (PET). These reactions open new opportunities to chemically transform aromatic polymers and modify their physical properties.

Gold-Catalyzed C-H Functionalization Polycondensation for the Synthesis of Aromatic Polymers.

Homogeneous gold (Au) complexes have demonstrated tremendous utility in modern organic chemistry; however, their application for the synthesis of polymers remains rare. Herein, we demonstrate the first catalytic application of Au complexes toward the polycondensation of alkyne-containing comonomers and heteroarene nucleophiles. Polymerization occurs through successive intermolecular hydroarylation reactions to produce high molecular weight aromatic copolymers with 1,1-disubstituted alkene backbone linkages. Clear correlations between the rate and degree of polymerization (DP) were established based on catalyst structure and counterion pairing, thus enabling polymerization reactions that proceeded with remarkable efficiency, high reactivity, and exceptional DPs. The reactivity is broad in scope, enabling the copolymerization of highly functionalized aromatic and aliphatic monomers. These results highlight the untapped utility of Au catalysis in providing access to new macromolecular constructs.