The segmented polyurethanes were synthesized by the reaction of polypropylene glycols having a different molecular weight and OH-terminated dimethylsiloxane with 4,4'-diphenyl methane diisocyanate (MDI) and N-methyl diethanolamine (MDEA) as a chain extender.
Diphenyl bis(4-isocyanatophenyl)silane as organosilicon diisocyanate was synthesized from corresponding diacid via Wienstock-Curtius modified rearrangement of diacidazide in benzene. This diisocyanate was reacted with N-methyl diethanolamine by the condensation polymerization to improve thermal resistance.
The structures of organosilicon diisocyanate and all resulting polymers in this study were identified by IR and $^1H$-NMR spectroscopy.
The obtained polyurethanes had inherent viscosity in the range of 0.25-0.36 dl/g.
The thermal stability of the polyurethanes was evaluted by TGA and Tg of the polymers was determined by using DSC. It was turned out that the incorporation of silicon atom increased their thermal stabilities and that the increasing molecular weight of polypropylene glycol as a soft segment decreased glass transition temperature.
분자량이 다른 폴리프로필렌 글리콜과 말단기가 수산기인 디메칠 디실록산을 MDI와, 연장쇄로서 N-메칠 디에탄올아민 (MDEA) 을 반응시키면 절편 폴리우레탄이 합성된다.
열적 성질을 개선하기 위해 유기 실리콘 디이소시아네이트를 합성하여 MDEA와 중합하여 폴리우레탄을 합성했다.
생성된 고분자 및 유기 실리콘 디이소시아네이트의 구조는 IR과 $^1H$-NMR 분광학에 의해 확인했다. 얻어진 폴리우레탄의 점도는 0.28-0.36 dl/g의 범위에 있었다.
폴리우레탄의 열적 안정도는 TGA로, 이의 Tg는 DSC로 측정했다.
실리콘 분자의 도입은 열적 안정도를 증가시켰고, 폴리프로필렌의 분자량이 증가함에 따라 Tg 값이 감소했다.
