Poly(disubstituted acetylene)s: Advances in polymer preparation and materials application

Conjugated polymers (CPs) have drawn great attention due to their excellent optical and electronic properties for decades. Among the varieties of CPs, polyacetylenes (PAs) triggered a revolution in polymer science due to their conductivity in highly doped state. Yet, the unstability and unprocessability of the pristine polyacetylene led researchers exploring their derivatives with substituents. Luckily, greatly improved stability and processability have been achieved by poly(disubstituted polyacetylene)s or PDSAs, that show efficient fluorescence emission in both solution and solid state and excellent circular polarized luminescence. This review summarizes recent research regarding PDSAs, beginning with the novel achievements of the discovery of the Pd-based catalyst systems for the polymerization of disubstituted acetylene monomers (DSAms), followed by a description of the effect of polymerization catalysts on the stereochemistry of obtained polymers and the effect of the stereochemistry on functional properties. Then, an updated summary of alternative synthetic routes to PDSAs, that is, post-polymerization modifications is contributed. This strategy has shown strong vitality due to the highly efficient reaction tools furnished by organic chemists such as click chemistry and activated esters. PDSAs usually possess intrinsically porous structure, exhibiting significant and variable fluorescent responses to exotic species such as solvents with different polarities, metal cations and explosives, and these properties indicate that PDSAs are promising candidates for fluorescent sensors and probes. Their reversible responses to applied fields such as stress and fluid gradient allow PDSAs to be active components of actuators. Moreover, due to the unique conjugated polyene main-chain and metathesis polymerization mechanism, PDSAs pronounced chirality transfer capacity and outstanding circular polarized luminescent property. Finally, an outlook of the application and suggestions of the synthetic efforts are forwarded.