Polarized FTIR spectroscopy experiments were carried out to investigate the effects of temperature on molecular arrangement of liquid crystal mixtures. Photo-reactive nematic liquid crystal LC242 (2-methyl-1,4-phenylene bis(4- (((4-(acryloyloxy)butoxy)carbonyl)oxy)benzoate)) was compared with a mixture of 5CB (4'-pentyl-[1,1'-biphenyl]-4- carbonitrile) having a relatively small molecular size and a mixture of PBN (4-phenylbenzonitrile) which is similar in molecular structure but not liquid crystal. As the temperature increased, the orientation of the liquid crystal axes remained the same in the liquid crystal film as well as in the cured liquid crystal film, but the degree of alignment decreased. PBN was interposed between the nematic arrays of LC242 similarly to 5CB, and the movement according to the temperature was the same. However, the order of the PBN molecules calculated by the order parameter value was lower than that of 5CB.

광반응성 네마틱 액정 LC242(2-methyl-1,4-phenylene bis(4-(((4-(acryloyloxy)butoxy)carbonyl)oxy)benzoate))와 분자 크기가 상대적으로 작은 액정 5CB(4'-pentyl-[1,1'-biphenyl]-4-carbonitrile), 분자구조는 액정과 유사하지만 액정이 아닌 PBN(4-phenylbenzonitrile)을 이용하여 액정혼합물을 제작하였다. 두 혼합물의 온도에 따른 분자 배열 변화를 편광 FTIR 분광실험을 이용하여 비교 조사하였다. 온도가 증가함에 따라 액정상에서 뿐만 아니라 경화시킨 액정필름에서도 분자들이 액정 축의 방향은 유지하지만 배열 정도가 감소하였다. 액정성을 띠지 않는 PBN도 액정 5CB와 비슷하게 LC242 액정의 네마틱 배열 사이에 끼어들어 같이 배열이 되며 온도에 따른 움직임도 동일하게 나타났지만, order parameter 값으로 계산한 분자들의 배열 정도는 5CB에 비하여 낮게 나타났다.

Keywords: reactive liquid crystal, mixtures, LC alignment, FTIR