초록
액정 polyurethane은 DMF 용매중 1,4-bis(6-hydroxyhexoxy)benzene (BHB6)과 2,5-tolylene diisocyanate (2,5-TDI)를 중부가 반응에 의해서 합성하였다. 고유점도는 0.26, $0.42d{\ell}/g$였다. 생성된 polyurethane의 열적성질 및 구조확인은 DSC, 편광현미경, X-ray회절 그리고 $^1H$-NMR 및 FT-IR에 의해 확인하였다 특히 분자량이 서로 다른 polyurethane 2,5-TDI/BHB6의 열적성질 및 물성에 대해서 비교 검토하였다. 고유점도가 [${\eta}$]=0.26인 polyurethane 2,5-TDI/BHB6는 monotropic 액정성을 나타내었다. 이러한 것은 구조적으로는 mesogen을 포함하고 있지 않다. 예를 들면 LCPU-L(저분자량)은 $T_{I-LC}$(등방성액체상전이점-액정) 및 $T_{LC-K}$(액정-결정)은 $122^{\circ}C$부터 $89^{\circ}C$까지 관찰되었다.
Liquid crystalline polyurethanes were prepared from 1,4-bis(6-hydroxyhexoxy)benzene (BHB6) and 2,5-tolylene diisocyanate (2,5-TDI) solution polymerization in dimethylformamide produced intrinsic viscosities in the range 0.26 and $0.42d{\ell}/g$. The polyurethanes were investigated by DSC, Polarizing microscopy, X-ray, $^1H$-NMR and IR spectroscopy. Polyurethanes of two different molecular weights were studied in detail and these will be referred to as low molecular weight and high molecular weight. Polyurethane 2,5-TDI/BHB6 with $[{\eta}]=0.26d{\ell}/g$ prepared from BHB6 and 2,5-TDI, exhibited monotropic liquid crystallinity, although these polyurethanes contained no mesogenic core unit. For example, LCPU-L(low molecular weight) exhibited $T_{I-LC}$ of $122^{\circ}C$ $T_{LC-K}$ $89^{\circ}C$.