| Budget Amount *help |
¥1,800,000 (Direct Cost: ¥1,800,000)
Fiscal Year 1990: ¥300,000 (Direct Cost: ¥300,000)
Fiscal Year 1989: ¥1,500,000 (Direct Cost: ¥1,500,000)
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| Research Abstract |
1. Aldol condensationーtype group transfer polymerization (GTP) of silyl dienyl ethers, CH_2=C (R) -CH=CH-OSi (CH_3)_3, [BdTMS (R=H); 3-MeBdTMS (R=CH_3); 3-PhBdTMS (R=C_6H_5)] was examined by using Lewis acid catalysts and aldehydes as an initiator. The best system of the initiatorーcatalyst was found as rhoーanisaldehydeーZnBr_2. Poly (BdTMS) obtained from the above system at 35^ﾟC showed Mn close to one calculated from [BdTMS]_0/ [Initiator]_0 and also molecular weight distribution (Mw/Mn=1.2-1.3).
2. Kinetic studies on GTP of BdTMS were carried out by NMR-monitoring. Formation of formylcation due to interaction between ーCH=0 at a polymer end (or initiator) and ZnBr_2 should be the rateーdetermining step for propagation (or initiation). In the case of ZnBr_2, the rate constant of the initiation was about 3 times that of propagation. Homogenious GTP was realized by addition of diethyl ether solvent, where the rate of polymerization could be described as Rrho=k [initiator] [ZnBr_2] [BdTMS]^2
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3. GTP of 3-MeBdTMS was accompanied by elimination of (CH_3)_3SiOSi(CH_3)_3 and forming cyclic ester in part. However, the Mw/Mn value of the polymer was 1.14.3-PhBdTMS was obtained as a mixture of EPSILON- (57%) and ZETA-geometric (43%) isomers. Under the conditions for GTP, it was revealed that only the EPSILON-isomer successfully gave the polymer with wellーregulated molecular weight (Mw/Mn=1.1) at the early stage of polymerization. The ZETA-isomer slowly polymerized in a different manner from GTP.
4. Complete desilylation of poly (BdTMS) was achieved in CH_3OH containing a small amount of (C_4H_9)_4NF, resulted in the polymer with ー [CH_2CH=CHCH(OH)]_n- linkage. By catalyーtic hydrogenation in the presence of Pd/charcoal, RhCl [P(C_6H_5)_3]_3, or PtO_2, this polymer could be converted to the polymer, - [CH_2CH_2-CH_2CH(OH)]_n-, which was recognized as an alternating ethyleneーvinyl alcohol copolymer. Acetylation of the hydrolyzed polymer, followed by catalytic hydrogenation, gave the alternating ethyleneーvinyl acetate copolymer. The molecular weight distribution of these alternating copolymers remained narrow in accordance with their parent polymer. Less
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