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 (nD) of 1.63-1.70 and Abbe numbers (vD) of 12.8-38.5. An investigation of the relationship of the vD values with the substituents on the benzene rings of the monomers indicates that methoxy and vinyl groups can collectively increase the vD values. In comparison with allyl groups, vinyl groups endow the polymers with both higher nD and vD. 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.