A new class of high refractive index polymers was developed through the thiol−ene coupling reaction of trivinylphosphine chalcogenides, [(CH 2 CH−)3PX (X = S, Se)], with 1,2-ethane dithiol and 1,3-benzene dithiol. The polymers were obtained through a thermal initiation and polymerization process which yielded robust monolithic materials. The polymers have good transmission properties in the visible region of the spectrum with very high refractive indices ranging from 1.66 to 1.75, placing them in the top echelon of high refractive index polymers, with Abbe numbers between 22 and 31. The high refractive index is due, in large part, to the presence of the highly polarizable PS and PSe groups, which have molar refractivities of 13.84 and 17.33 mol/cm 3 , respectively. The polymers tend to have a high cross-link density that varies with the composition but results in rigid materials for most compositions. The glass-transition temperatures (T g ) for all but one composition were above 70 °C, and the storage moduli ranged from 1.5 to 3.8 GPa. The 1,2-ethane dithiol compositions had lower values of T g than the 1,3-benzene dithiol materials. This was attributed to a lower cross-link density in the 1,2-ethane dithiol polymers, as determined from the residual unreacted vinyl groups measured by Raman spectroscopy and 31 P solid-state nuclear magnetic resonance spectroscopy. The PSe polymers were slower to react and required higher temperatures; they also produced the hardest materials with the highest refractive indices.

Transparent hybrid organic methacrylate capped zirconium oxo‐clusters (ZOCs) with thiol‐ene monomers. The vinyl capping groups potentially enable the ZOCs to become an integral part of the thiol‐ene network. The ZOCs are reasonably soluble in the thiol‐ene monomers yielding a loading of 1 wt. ‐%. The resulting polymer composites were highly transparent in the visible region and exhibited significant enhancement in the refractive indices with measured values ranging from 1. 714 to 1. 744. Moreover, dynamic mechanical analysis (DMA) revealed that all the composites exhibited good mechanical strength and were robust enough to undergo machining and/or polishing without fracture.

A series of hard, transparent, thermoset polymer samples containing tetravinylsilane (TVS) and 1,3‐benzenedithiol (BDT) with varying loadings of zirconium oxide clusters Zr6(OH)4O4(OMc)12 (ZOC) were synthesized. Resulting polymers exhibited a higher refractive index (n) than the parent polymer containing only the monomers TVS and BDT. The refractive index reached a maximum value of 1.711 at a ZOC loading of 3 wt% and then decreased as the ZOC concentration in the polymer matrix increased. The refractive index of ZOC was determined to be 1.540 using the Becke line method. Because the refractive index of ZOC is lower than that of the TVS–BDT polymer matrix, the finding that the incorporation of small quantities of ZOC can increase the refractive index of the TVS–BDT polymer composite was unexpected and is accounted for by the effects of ZOC on the packing efficiency of the composite.