High Refractive Index Polymers Based on Thiol–Ene Cross-Linking Using Polarizable Inorganic/Organic Monomers

Abstract

The self-initiation of the thiol–ene coupling reaction of tetravinyl monomers containing main group elements and trivinyl heterocycles with alkyl and aryl dithiols resulted in the formation of highly cross-linked prepolymer gels which upon final curing at 120 °C yielded hard, monolithic polymeric materials. Because of the presence of highly polarizable main group elements such as Si, Ge, Sn, and S and the relative absence of highly electronegative elements, the resulting polymers exhibited high refractive indices ranging from 1.590 to 1.703 and Abbe numbers between 24.3 and 45.0. All of the polymers were highly transparent over the UV–vis region of the spectrum. Moreover, due to the high cross-linked density achievable in specific compositions, very hard materials capable of being ground and polished could be produced. The range of compositions produced yields important structure–property relationships, indicating the effect of monomer structure on mechanical and optical properties.

Renewable sulfur-containing thermoplastics via AB-type thiol-ene polyaddition

“…However, storage of the purified product at room temperature should be avoided as a precipitation of crystalline oligomeric polythioethers occurs due to self-initiation. The successful isolation of an α-olefinic ω-thiol and especially its long-term stability is surprising, since there are several reports of self-initiated thiol-ene reactions, where no initiator is needed for the (poly)addition to proceed [26,27].…”

Protected thiol strategies in macromolecular design

“…Normally, it is more difficult to react non-activated alkenes in a thiol-ene reaction. However, double bonds activated with silane groups were already proven to be quite reactive towards radical reactions [202]. When two silane groups are activating the unsaturated bond, the reactivity is even increased, as shown by Vandervoort and co-workers [201].…”

Synthesis and Solution Self‐Assembly of Polyisoprene‐block‐poly(ferrocenylmethylsilane): A Diblock Copolymer with an Atactic but Semicrystalline Core‐Forming Metalloblock

“…104 Notably, the inclusion of highly polarisable atoms (Si, Ge, Sn, S), substituents with low molar volumes and high molar refractions (aromatic rings, halogens excluding F), or metallic elements into macromolecules increases the RI exhibited by the material without significantly increasing the optical dispersion. 106,107 Frequently, as several components are combined in a polymer, the refractive index of the material is increased further by synergistic effects.…”