Synthesis and properties of poly(2-adamantyl vinyl ether)-based optical plastics

Cationic polymerization of 2-adamantyl vinyl ether (2-vinyloxytricyclo[3.3.1.1(3,7)]decane; 2-AdVE) and copolymerization of 2-AdVE with n-butyl vinyl ether (NBVE), 2-methoxyethyl vinyl ether (MOVE), or 2-(2-vinyloxyethoxy)ethyl acrylate (VEEA), vinyl ethers containing a flexible chain or a polymerizable group, were performed to obtain poly(vinyl ether) plastics for optical use. With the living cationic initiating systems such as isobutyl vinyl ether-acetic acid adduct/ethylaluminum sesquichloride (IBEA/Et1.5AlCl1.5) or the hydrogen chloride/zinc chloride (HCl/ZnCl2), all the obtained copolymers had unimodal and relatively narrow molecular weight distributions (polydispersity ratio: M (w)/M (n) = similar to 1.5 at high conversion) throughout the copolymerizations. These results indicate that the copolymerizations of 2-AdVE with the three comonomers led to the statistical copolymers without contamination of homopolymers. With BF3OEt2 as an initiator, homopolymer of 2-AdVE and poly(2-AdVE)-based polymers, poly(2-AdVE-stat-NBVE), poly(2-AdVE-stat-MOVE), and poly(2-AdVE-stat-VEEA), were produced with high-molecular weights (M (n) = 31,800-116,000) in toluene at -30 A degrees C in quantitative yield within 10 min. They have excellent thermal stability owing to their high glass transition and thermal decomposition temperatures. The transparency (86-91 %) and refractive index (1.52-1.53) of the molded polymers are similar to those of conventional optical plastics such as poly(methyl methacrylate) (PMMA) and polycarbonate (PC), whereas their specific gravity (1.09-1.12) and water absorption (0.06-0.17 %) are significantly lower than those of PMMA and PC. In addition, the Abbe number of poly(2-AdVE), poly(2-AdVE-stat-NBVE), and poly(2-AdVE-stat-MOVE) exceeded 60 and was higher than those of PMMA and PC, indicating that the poly(2-AdVE)-based plastics are very suitable for optical lens.