Polymeric materials synthesis and processing in supercritical carbon dioxide
- Univ. of North Carolina, Chapel Hill, NC (United States)
Fluoropolymers are used in technologically demanding applications because of their high-performance properties. An impediment to the synthesis of commercially available fluoropolymers is their general insolubility in most solvents except chlorofluorocarbons (CFC`s). The environmental concerns about CFC`s can be avoided by preparing fluoropolymers in supercritical fluids (SCF`s). The homogeneous solution homo- and copolymerization of highly fluorinated acrylic, styrenic and olefinic monomers in SC CO{sub 2} using free radical methods will be discussed. Homogeneous solution polymerization studies allowed us to consider heterogeneous polymerizations in a CO{sub 2} continuous phase. Conventional heterogeneous polymerization of unsaturated monomers is performed in either aqueous or organic dispersing media with addition of surfactants. An environmentally responsible alternative to aqueous and organic dispersing media for heterogeneous polymerizations utilizes SC CO{sub 2} in conjunction with molecularly engineered amphiphilic molecules designed to be interfacially active in CO{sub 2}. Conventional lipophilic monomers can be polymerized heterogeneously using conventional initiators in liquid, and SC CO{sub 2} in the presence of added stabilizer, to form stable emulsions of monodisperse, micron-size spherical particles. Quantitative yields can be achieved. This process opens the way to new structured latexes, composite materials, and interpenetrating polymer networks not accessible by conventional methods.
- OSTI ID:
- 214882
- Report Number(s):
- CONF-950801--
- Country of Publication:
- United States
- Language:
- English
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