Development of Polymer Membranes for Gas/Organic Vapor Separation by Using Substituted Polyacetylenes

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1. Synthesis of Poly (diphenylacetylenes) with Ring-Substituents and Its Gas Permeability-Polymerization of diphenylacetylenes (DPA) with various substituent and polymer properties were investigated. TaCl_5/organometallic cocatalyst systems proved to be quite effective for the polymerization of diphenylacetylenes, providing high molecular weight polymers in good yields. Most of the produced polymers are completely soluble in organic solvents. High thermal stability and film-forming ability of the polymers make it possible to prepare thin tough membranes with high gas permeability. Interestingly, quite large P_<O2> values (P_<O2>〜1100 barrer) were observed with poly (DPAs) bearing bulky round-shaped para-substituents such as tert-butyl and trimethylsilyl.2. Synthesis and Properties of Poly (phenylacetylene) with Bulky Silyl Groups-Polymerization of p-[tris (trimethylsilyl) silyl] phenylacetylene [p (Me_3Si)_3SiPA] and chiral silicon-containing (+)-1-p-{[methyl (1-naphthyl) phenyl]silyl} … More phenylacetylene (MeNpPhSi^*PA) was studied. Homopolymerization of p(Me_3Si)_3SiPA by Rh catalyst provided insoluble polymer. On the other hand, copolymerization of p(Me_3Si)_3SiPA with p-(trimethylsilyl) phenylacetylene at various feed ratios afforded high molecular weigh copolymers in high yields, all of which were soluble in many organic solvents. The P_<O2> value of the copolymer for the 80 : 20 feed ratio reached 770 barrer. The Rh-based poly (MeNpPhSi^*PA) showed a very large optical rotation. Its circular dichroism spectrum exhibited very large Cotton effects in the UV region in CHCl_3. The P_<O2> value of poly (MeNpPhSi^*PA) was 900 barrers.3. Gas-Permeation Behavior of Poly (diphenylacetylene) with Trimethylsilyl and Triisopropylsilyl Groups-Gas permeation behavior of poly (diphenylacetylenes) with trimethylsilyl and triisopropylsilyl groups (PTMSDPA and PTPSDPA, respectively) was investigated. The gas permeability coefficients of both polymers were very high, and these polymers were more permeable to larger, condensable vapors hydrocarbons (e.g., n-butane) than to small, permanent gases (e.g., hydrogen). As temperature increased, the permeability in PTMSDPA increased for light gases (helium, hydrogen, and nitrogen) and decreased for more condensable gases. Less