Cyclic Olefin Terpolymers with High Refractive Index and High Optical Transparency

Cyclic olefin copolymer (COC) is one of the most promising optical materials; however, the brittle COC suffers from issues including a low refractive index. In this contribution, by the introduction of high refractive index comonomers including phenoxy substituted α-olefin (C4OAr), p-tolylthio substituted α-olefin (C4SAr) and carbazolyl substituted α-olefins (C4NAr, C3NAr, and C2NAr), the zirconocene mediated terpolymerization of ethylene (E) and tetracyclododecene (TCD) produces the preferred E-TCD-CnNAr (n = 2, 3, and 4) cyclic olefin terpolymers (COT) with tunable compositions (TCD: 11.5- 35.8 mol %, CnNAr: 1.2-5.0 mol %), high molecular weights and high glass transition temperatures (up to 167 °C) in high catalytic activities. Compared to the E-TCD copolymer (COC) material, these COT materials show the comparable thermal decomposition temperature (Td,5% = 437 °C), slightly higher strain at break value (up to 7.4%) and higher tensile strength (up to 60.5 MPa). In particular, these noncrystalline optical COT materials have significantly higher refractive indices of 1.550-1.569 and are more transparent (transmittance: 93-95%), relative to the COC materials, indicative of an excellent optical material.