Novel second-order nonlinear optical main-chain polyurethanes: Adjustable subtle structure, improved thermal stability and enhanced nonlinear optical property

A series of main-chain polyurethanes containing sulfonyl-based NLO chromophores in the polymer backbone were prepared, the subtle structure of the chromophore moieties could be easily modified to adjust the property of the resultant polymers. The polymers exhibit improved stability of their enhanced NLO effects, besides their good processability, thermal stability, and relatively good transparency. The tested NLO properties of the polymers demonstrate that there is a suitable isolation group present for the sulfonyl-based chromophore to boost its microscopic β value to possibly higher macroscopic NLO property efficiently, and BOP moieties are the best choice for this series of polymers to achieve optimized properties.