Y. Okamoto, Hong-xiang Teng
2009
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Chimica Oggi-chemistry Today
Abstract
Various perfluoro-2-methylene-1,3-dioxolanes substituted on 4 and 5 positions were synthesized from corresponding hydrocarbon precursors by direct fluorination in fluorinated solvent by F 2 / N 2 mixture. These perfluorodioxolane monomers were readily polymerized in bulk at 60-80°C using a perfluoroperoxide as the free radical initiator. The polymers obtained are completely amorphous. The refractive indexes and the glass transition temperatures are in the range of 1.3280 ~ 1.3570 at 632 nm and 90-185°C, respectively. They exhibit extraordinary optical transmittance from UV to near IR. They are chemically as well as thermally stable. The polymer obtained from perfluoro-2-methylene-1,3-dioxolane (without substitute on 4 and 5 position) was semi crystalline and melted at 230°C. However, when the crystalline powder was heated above the melting temperature and pressed, it became an amorphous transparent and flexible film and did not recrystallize below the glass transition temperature (110°C). The copolymers of these perfluorodioxolane monomers are also readily prepared in the solution or in bulk. The copolymers have only one T g from 110 to 165°C depending on the copolymer composition. The films prepared by casting were flexible and tough and had high optical transparency. The perfluorodioxolane polymers synthesized have extraordinary properties similar to commercially available perfluoropolymers such as Teflon AF ® , Hyflon AD ® and Cytop ® , and may have a wide range of applications in advanced optical and electronic technologies.