Synthesis and Characterization of High Refractive Index Polythiocyanurates

Abstract

The polythiocyanurates with high molecular weights were successfully prepared by the phase-transfer catalyzed polycondensation of triazinedithiol with activated dibromides. These polymers were soluble in tetrahydrofuran (THF) and N -methyl-2-pyrrolidone (NMP), and readily afforded colorless and transparent cast films. The films of polythiocyanurates exhibited good thermal stabilities such as thermal decomposition temperatures of 320 ˚C in air. A relatively high glass transition temperatures of the polymers were in the range of 112-143 ˚C. The optical transmittance of the films was as high as 80% at 400 nm. The films exhibited high refractive index of 1.73 at d line, which is attributed to the triazine rings and sulfur atoms, and Abbe's number of around 18. Furthermore, the f ilms showed the low birefringence of 0.0007-0.0022 at d-line. The obtained polymers are promising candidates for thermoplastic optical lens application. Copolymers of polysilane and allyl methacrylate were prepared using the polysilane as a photoradical initiator. The polysilane block and allyl group were retained even after photopolymerization. The σ -conjugation of polysilane block in the copolymer allowed it to exhibit light absorption in the ultraviolet region. Subsequently, an ene-thiol reaction between the copolymer and mercapto-containing molecule was carried out by photocuring a thin film of the mixture. The photoreaction formed –CH–CH 2 –S– bonding between the organic component and a silica component that was formed by photolysis of the polysilane block in the copolymer. Therefore, the polysilane-allyl methacrylate copolymer successfully provided a silicon-rich organic–inorganic hybrid material.