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

Four biobased phosphate-containing\naryl monomers with methoxy,\nallyl, and vinyl groups as substituents have been successfully synthesized.\nCopolymerizing these monomers with thiophenol or mercaptans via the\nphotoclick thiol–ene reaction gives the polymers with refractive\nindices (<i>n</i><sub>D</sub>) of 1.63–1.70 and Abbe\nnumbers (<i>v</i><sub>D</sub>) of 12.8–38.5. An investigation\nof the relationship of the <i>v</i><sub>D</sub> values with\nthe substituents on the benzene rings of the monomers indicates that\nmethoxy and vinyl groups can collectively increase the <i>v</i><sub>D</sub> values. In comparison with allyl groups, vinyl groups\nendow the polymers with both higher <i>n</i><sub>D</sub> and <i>v</i><sub>D</sub>. Moreover, these polymers also\ndisplay high transmittance, high thermostability, and low haze values\nin the visible-light region, suggesting that these biobased functional\nmonomers are satisfactory precursors used in the fabrication of optical\ndevices.