Photocurable selenophene/maleimide-based high-refractive-index copolymers obtained via radical copolymerization

• Published in: Reactive & functional polymers 2021-08, Vol.165, p.104960, Article 104960
• Main Authors: Tokushita, Yoshihisa, Watanabe, Airi, Torii, Ayaka, Nakabayashi, Kazuhiro, Samitsu, Sadaki, Mori, Hideharu
• Format: Article
• Language: English
• Subjects: Abbe number; Chemical synthesis; Copolymerization; Copolymers; Free radical polymerization; Glass transition temperature; High refractive index polymer; Maleimide; Nanoparticles; Photocuring; Polymerization; Refractivity; Selenophene; Temperature effects; Thermal stability; Thiol-ene reaction; Ultraviolet radiation
• ISSN: 1381-5148; 1873-166X
• DOI: 10.1016/j.reactfunctpolym.2021.104960

Selenophene-containing copolymers with either alternating or random sequences and high refractive indices were synthesized via conventional free-radical copolymerization of 2-vinylselenophene (2VS). Copolymers with a moderate alternating tendency were obtained via radical copolymerization of electron-donating 2VS and electron-accepting maleimide derivatives, such as N-methyl maleimide (MMI), N-phenyl maleimide (PMI), and N-vinyl maleimide (VMI). Copolymerization of 2VS with glycidyl methacrylate (GMA) also afforded copolymers containing selenophene and reactive epoxy units in the side chains. The selenophene-containing poly(2VS) showed a high refractive index (1.6420 @ 589 nm) and a reasonable Abbe number (30.7). High refractive indices of 1.6138–1.5959 with corresponding Abbe numbers of ~30 were similarly achieved for the selenophene/maleimide copolymers. The introduction of the maleimide moiety into the polymer side chain improved its thermal stability (Td5 > 320 °C) and enhanced the glass transition temperature (Tg = 158–160 °C). Selenophene-containing copolymers with pendant N-vinyl units were obtained via copolymerization of 2VS and VMI, which was successfully employed as a precursor for obtaining a photoinduced crosslinked film via a thiol-ene reaction with 1,6-hexanedithiol in the presence of a photo-radical initiator under ultraviolet irradiation. Thus, for the first time, photocurable and high-refractive-index selenophene-based copolymers were developed through the combination of a selenophene-containing vinyl monomer and a maleimide derivative with a pendant N-vinyl group. [Display omitted] •Photocurable and high-refractive-index selenophene-based copolymers were developed for the first time.•A moderate alternating sequence was obtained via radical copolymerization of electron-donating 2-vinylselenophene and accepting maleimides.•High refractive indices of 1.6138–1.5959 with Abbe numbers of approximately 30 were achieved for the selenophene/maleimide copolymers.•Selenophene/maleimide copolymers exhibited high thermal stability (Td5 > 320 °C) and enhanced glass transition temperature (Tg = 158–160 °C).•Selenophene-containing copolymers with pendant N-vinyl units were employed as a precursor for obtaining a photoinduced crosslinked film via a thiol-ene reaction.