Half-sandwich titanocene catalysts such as cyclopentadienyltitanium trichloride (CpTiC13), indenyltitanium trichloride (IndTiC13), fluorenyltitanium trichloride (FluTiC13), trimethylsilylindenyltitanium trichloride ((Me3Si)IndTiCl3) and pentamethylcyclopentadienyltitanium trichloride (Cp*TiCl3) have been examined with modified methylaluminoxane(MMAO) for styrene polymerization. IndTiC13 showed higher activity than CpTiC13. Polystyrene (PS) of the highest syndiotactic index and molecular weight was obtained by using Cp*TiCl3. By supporting IndTiC13 or Cp*TiCl3 on silica or cyclodextrin, the catalyst had a reasonable activity even with a smaller amount of MMAO compared to the unsupported catalysts. For microtacticity observed with 3C-NMR, PS of higher syndio triads [rr] was obtained by using IndTiCl3 or Cp*TiCl3 instead of CpTiCl3. Crystalline structure of sPS was found to be mainly δ form with X-ray Diffractometer.
Half-sandwich형 titanocene 촉매인 cyclopentadienyltitanium trichloride (CpTiCl3), indenyltitanium trichloride (IndTiC13), fluorenyltitanium trichloride (FluTiCl3), trimethylsily-lindenyltitanium trichloride ((Me3Si)IndTiC13) 및 Pentamethylcyclopentadienyltitanium trichloride (Cp*TiC13) 등과 공촉매로 modified methylaluminoxane (MMAO)을 사용하여 스티렌중합을 행하고 그들의 중합거동을 조사하였다. IndTiC13가 CpTiCl3 보다 높은 촉매활성을 보였고, 폴리스티렌의 분자량 및 신디오탁틱 지수는 Cp*TiCl3 촉매를 사용한 경우에 가장 높게 나타났다. 또한 IndTiC13 및 Cp*TiCl3를 실리카 또는 시클로덱스트린에 담지시켜 제조한 촉매는 적은 양의 MMAO를 사용하고도 높은 촉매활성을 나타내었다. 중합체의 미세구조를 13C-NMR로 조사한 결과, CpTiCl3로 얻은 sPS에 비해 IndTiC13 및 Cp*TiC13로 얻은 것의 입체규칙성이 더 높았다. X-ray Diffractometer로 분석한 sPS의 결정구조는 대부분 δ형이었다.
Keywords: syndiotactic polystyrene; half-sandwich titanocene; activity; syndiotactic index