2,3-Dihydrofuran(DHF) and 5-methyl-2,3-dihydrofuran(MDHF) were polymerized by various transition metal catalyst systems in toluene at -78℃. The catalyst systems were consist of a basic tungsten catalyst, a stoichiometric tungsten catalyst, and a pretreated stoichiometric tungsten catalyst, i.e., $WCl_6$, $WCl_6: Et_2AlCl(1:4)$, and $WCl_6:Et_2AlCl$:Base(1:4:0.2), respectively.
The higher polymerization yields of DHF and MDHF were obtained in the SW and the PSW catalyst system than in the basic catalyst system. And the high molecular weight polymers were obtained by these catalyst systems.
The stereochemical structures of the resulting polymers were determined by PMR, CMR, and IR spectra. All transition metal catalyst gave very high stereoregularity for the polymerization of MDHF, but did not for the polymerization of DHF. And the PSW catalyst gave the best stereoregular polymer in the polymerization of MDHF. The major stereochemical structure of this polymer was erythro-diisotactic, and the percent of erythro-diisotactic structure was about 80% for the SW catalyst and 90% for the PSW catalyst according to NMR integration.
PMDHF was insoluble in methyl ketone which is used as the measure of the stereoregularity, but PDHF was partially soluble. This behavior indicates that PMDHF has very high stereoregularity.
PDHF and PMDHF were simultaneously decomposed at the range of 300-420℃. And PDHF had Tg of 136℃.
The model approach to the polymer structure and the action mechanism of these catalyst were investigated in detail.
본 논문은 여러가지 전이금속 촉매에 의한 DHF 와 MDHF의 입체규칙성 중합에 관한 연구로서, 새로운 촉매체계를 개발하여 높은 분자량을 가지며, 열에 안정하고 높은 입체규칙성을 갖는 고분자를 만드는 데 성공하였다.
촉매체계는 기본 텅스텐 촉매, 화학 양론적 텅스텐 촉매( SW ), 전치 화학 양론적 텅스텐 촉매( PSW ) 등으로 구성되며, SW촉매와 PSW 촉매는 DHF 과 MDHF 중합에서 기본 텅스텐 촉매보다 높은 중합 수율을 보였으며, 특히 MDHF 의 중합에 대해서는 높은 입체규칙성을 보였다.
고분자의 입체적 구조는 모델 연구 및 고성능 기기분석 스펙트럼을 통해 확인하였는데, 그 구조는 erythro-diisotactic 이었으며, SW 촉매에 대해서는 80%, PSW 촉매에대해서는 90%의 입체규칙성을 나타내었다. 그러나 DHF 는 어떤 촉매 체계에 대해서도 입체규칙성 고분자를 생성하지 않았다. 뿐만 아니라 PMDHF는 입체규칙성 판별 기준으로 사용되는 메틸 에틸 케톤에 전혀 녹지 않았으므로 높은 입체 규칙성을 갖는다는 것을 알수 있었다.
PDHF 과 PMDHF 는 300-400℃ 범위에서 동시에 분해되었고 PDHF만이 136℃에서 Tg를 가졌다.
상세한 모델 연구를 통해 고분자의 구조 및 촉매들이 작용하는 메카니즘을 자세히 규명하였다.
