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

Abstract

Copolymerization of norbornene (NB) and fluorene-containing alkene comonomers using the Me 2 Si(Flu)(N t Bu)-TiMe 2 complex as a catalyst was investigated. The copolymerization successfully proceeded at any monomer feed ratio in high activity and gave copolymers with various comonomer contents. The structure of these copolymers would be gradient because NB was preferentially consumed in a quasi-living polymerization system. Two relaxation processes at 100−150 and 270−300 °C in dynamic mechanical analysis, which show phase-separation of the copolymer, supported the formation of the gradient structure. The obtained copolymers showed a high refractive index as hydrocarbons and extremely low photoelasticity (<10 −11 Pa −1 ). For reducing the photoelasticity, a monomer design free from reactive tertiary carbons would be important.

Synthesis and properties of cyclic olefin polymers by ring-opening metathesis (co)polymerization of α-methyl-substituted norbornene lactones

“…Specifically, the high refractive index of the perpendicular direction can be offset by introducing high refractive index aromatic groups into the side chain. [20][21][22][23][24][25] However, a systematic investigation of such optical properties in COPs and COCs is still required. Understanding the relationships between the primary structure of the polymer and its thermal and optical properties is of great significance.…”

Cyclic Olefin Terpolymers with High Refractive Index and High Optical Transparency

“…Notably, with an only 5.0 mol % incorporation of the carbazolyl group, a significantly high refractive index of 1.569 is accessible. This reveals an efficient method to enhance the desired refractive index of COC …”

“…One shortcoming of the optical properties in these notable COC materials is the relatively low refractive indices of 1.52–1.54, however. How to enhance the refractive index of COC is a paramount but greatly challenging project, because even a small increase on the refractive index makes a great impact on optical materials in terms of diverse design; and much less attention has been paid to produce novel high refractive index COC, although numerous COCs have been disclosed and studied. ,− In principle, introducing an atom or a substituent with a high molar refraction into the polymer chain can increase the intrinsic refractive index of the material, and these atoms or groups including sulfur, aromatic groups, halogens (except fluorine) are significantly promising candidates . Particularly, the carbazole unit stands out from these high refractive index groups including diphenylmethane ( n = 1.578), fluorene ( n = 1.640), o -phenylphenol ( n = 1.610), diphenylamine ( n = 1.636), and carbazole ( n = 1.708) …”

“…This reveals an efficient method to enhance the desired refractive index of COC. 8 The optical transparency of COC and these COT samples that are noncrystalline is another key optical parameter and is further studied over the range of visble light from 400 to 800 nm (Figure 2f). The film thickness of samples is comparable in the range of 28−38 μm, and they are very transparent.…”

Cyclic Olefin Copolymers (COC)—Excellent Glass Formers with Low Dynamic Fragility

“…Applications of COCs are manifold and range from materials for advanced packaging, [6,7] thermal insulation, [8] gas separation [9] to optical [10][11][12] and microfluidic devices for diverse applications [13][14][15][16] or artificial muscles [17] and optical biosensors. [18,19] Developing a full understanding of the characteristics of the glass transition behavior of these materials is important to their processing and use in a variety of those applications.…”