Cyclic Olefin Copolymer Bearing Pendant Fluorenyl Groups with High Refractive Index and Low Chromatic Dispersion

Chemically Recyclable Poly(tetrathioorthocarbonate)s: Combining High Refractive Index and Abbe Number

Polymers with high refractive index (n) and Abbe number (vD) have the potential to be used in advanced optical devices. However, fabricating such materials is challenging because of the inherent trade-off between light refraction and dispersion. Herein, we present an efficient strategy for synthesizing sulfur-rich polymers with tetrathioorthocarbonate as the functional group through the alternating copolymerization of thiiranes and cyclic trithiocarbonates in a controlled fashion. Notably, the tetrathioorthocarbonates with features of high sulfur content, cyclic structure, and free C═S bonds afforded excellent optical properties with an n under 589.3 nm of 1.706, vD of 40.9, and optical transparency of 90%. Density functional theory calculations of the copolymerization process suggest that the high selectivity of poly(tetrathioorthocarbonate)s (PTOCs) originates from the thermodynamically unfavorable elimination of trithiocarbonate anions. In particular, PTOCs can be recycled to the original thiiranes and cyclic trithiocarbonates via spiro intermediates by simple pyrolysis.

Fluorinated Cyclic Olefin Copolymers (COCs) and Cyclic Olefin Polymers (COPs)

The demand for insulating materials with superior dielectric properties has increased. Among these materials, polymers containing cyclic structure including cyclic olefin copolymer (COC) and cyclic olefin polymer (COP) stand out because of their excellent dielectric properties originating from the pure hydrocarbon structure. Introducing fluorine into polymers is one efficient strategy for optimizing the dielectric and the related important properties. Here, three fluorinated norbornene derivatives with high fluorine content are synthesized and copolymerized via coordination-insertion polymerization (CIP) and ring-opening metathesis polymerization (ROMP). The obtained fluorinated COCs and COPs have high fluorine contents (up to 48.2 wt.%) and exhibit excellent dielectric properties with dielectric constant (Dk) of 2.11-2.24 and dielectric loss (Df) of 0.0021-0.0031 at 10 GHz. Moreover, these fluoropolymers show good solvent tolerance, high toughness (elongation at break up to 779%), enhanced thermal stability (Td,5% of 427-440 °C), low hydrophilicity (water uptake <0.01%), and excellent gas separation properties. These results imply that these fluoropolymers are suitable as a potential candidate for substrate material utilized in the application of insulating materials.

High-Refractive-Index Cross-Linked Cyclic Olefin Polymers with Excellent Transparency via Thiol-Ene Click Reaction

High-refractive-index polymers are important optical materials in optoelectronics. Conventional cyclic olefin polymers (COPs), possessing many excellent optical properties, are a class of highly promising optical materials; however, one of the greatest obstacles is their low refractive index of n = 1.52-1.54. Here, one efficient strategy of first incorporating high molar refraction groups, including carbazolyl and indolyl moieties, into unsaturated COPs via ring-opening metathesis polymerization (ROMP) and then introducing another high molar refraction sulfur atom by a subsequent thiol-ene click reaction is presented. The obtained cross-linked COPs bearing both an aromatic group and sulfur possess significantly higher refractive indices (n = 1.611-1.684 at 589 nm) and highly optical transparency (approximately 95%) in the range of vis-NIR. This provides a way toward potential applications of new-generation optical materials.

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-C_nNAr (n = 2, 3, and 4) cyclic olefin terpolymers (COT) with tunable compositions (TCD: 11.5- 35.8 mol %, C_nNAr: 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 (T_d,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.