Synthesis of Bimodal Distributed Cyclic Olefin Copolymers with Improved Tensile Properties

Abstract

Ethylene/norbornene(NBE) copolymers are the most representative and widely-used cyclic olefin copolymers (COCs). Higher NBE content in COCs leads to higher transparency, glass transition temperature and mechanical strength, but also makes the COC more brittle and therefore hampers its end uses. In this study, to improve the brittleness of COCs while maintaining their high strength, heat-resistant and transparency, bimodal distributed COCs have been prepared via two selective catalysts reactive blending in one pot. The shape of the molecular weight distribution curves of the obtained COCs could be easily controlled by adjusting the proportion of the two catalysts. These COCs maintained high glass transition temperature, balanced tensile performance, high transparency. Roles of the molecular weight and NBE incorporation in physical properties of the COC blends were studied. As we proved, the bimodal distribution COCs, which were composed of COC with high NBE incorporation, high molecular weight and COC with low NBE incorporation, low molecular weight, showed evident improvement in tensile properties (elongation at break up to 9.6%, tensile strength beyond 50.5 MPa), which were more flexible than the neat ethylene/NBE copolymer, while their glass transition temperatures were almost equally high (beyond 130 C).

Simultaneously improving of thermal resistance and mechanical performances of cyclic olefin copolymers by incorporation of bulky adamantane side group

“…[1][2][3][4][5][6][7] Furthermore, COCs display lower moisture absorption, better radiation resistance and lower birefringence compared to the common optical plastics as polymethylmethacrylate (PMMA) and polycarbonate (PC). [8][9][10][11][12] Therefore, COCs could be employed as an ideal alternative of PMMA and PC in various fields. As a typical COCs, copolymer of ethylene with norbornene (NBE) shows decent thermal resistance and high transparency.…”

“…Cyclic olefin copolymers (COCs) always show high transparency, outstanding chemical resistance, and dimensional stability 1–7 . Furthermore, COCs display lower moisture absorption, better radiation resistance and lower birefringence compared to the common optical plastics as polymethylmethacrylate (PMMA) and polycarbonate (PC) 8–12 . Therefore, COCs could be employed as an ideal alternative of PMMA and PC in various fields.…”

Bidentate Pyridyl‐Amido Hafnium Catalysts for Copolymerization of Ethylene with 1‐Octene and Norbornene

“…Interestingly, recent studies have shown that the elastic properties can also be installed through branching formation via chain walking homopolymerization of ethylene [28–32] . The incorporation of cyclic comonomers such as norbornene endows cyclic olefin copolymers ( COC ) with unique properties such as high heat stability, good chemical resistance, low density and high transparency [33–35] …”

“…[28][29][30][31][32] The incorporation of cyclic comonomers such as norbornene endows cyclic olefin copolymers (COC) with unique properties such as high heat stability, good chemical resistance, low density and high transparency. [33][34][35] To efficiently prepare the abovementioned copolymers, the catalysts must possess high reactivity toward these comonomers, along with the capabilities of incorporating a large amount of comonomers. The design and development of highperformance copolymerization catalysts are crucial for the further evolution of these copolymer materials.…”

Cyclic Olefin Terpolymers with High Refractive Index and High Optical Transparency

“…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) …”