Aromatic Polyphosphonates with Ultra-High Refractive Indices

Highly refractive and transparent polyphosphonates with varying aromatic backbones have been synthesised by polycondensation of phosphonic dichlorides and diols. The polyphosphonates display excellent thermal properties, with most thermally stable to up to 450°C. The glass transition temperatures of the polymers could be readily tuned from 41-214°C by terminating the polymer with different alcohols. The polymers synthesised also possess exceptional optical properties, with low UV cut off points and ultra-high refractive indices up to 1.70, the highest reported for this type of polymer. Most importantly, the polymers also display high Abbe numbers (≥52), the highest reported for intrinsic HRIPs, displaying an unprecedented combination of these two key optical metrics.