Biobased Sulfur- and Phosphate-Containing High-Refractive-Index Polymers: Substituent Effects on Optical Properties of Polymers

Four biobased phosphate-containing aryl monomers with methoxy, allyl, and vinyl groups as substituents have been successfully synthesized. Copolymerizing these monomers with thiophenol or mercaptans via the photoclick thiol-ene reaction gives the polymers with refractive indices (<i>n</i>_D) of 1.63-1.70 and Abbe numbers (<i>v</i>_D) of 12.8-38.5. An investigation of the relationship of the <i>v</i>_D values with the substituents on the benzene rings of the monomers indicates that methoxy and vinyl groups can collectively increase the <i>v</i>_D values. In comparison with allyl groups, vinyl groups endow the polymers with both higher <i>n</i>_D and <i>v</i>_D. Moreover, these polymers also display high transmittance, high thermostability, and low haze values in the visible-light region, suggesting that these biobased functional monomers are satisfactory precursors used in the fabrication of optical devices.