A thermotropic liquid crystalline polymer (TLCP) nanocomposite was synthesized via in-situ intercalation polymerization of 4-(4-acetoxy-1,4-phenyleneoxytetramethyleneoxy)benzoic acid, which was newly synthesized in the presence of organoclay. Organoclay was prepared by the cation exchange reaction of sodium-montmorillonite (Na⁺-MMT) with a solution of the ammonium salt of ethyl-4-aminobenzoate (EAB). Ethyl-4-aminobenzoate-montmorillonite (EAB-MMT) and Cloisite^® 30B were used in the formation of TLCP hybrids. The thermal properties, morphologies, and liquid crystalline phases of TLCP hybrids with two different organoclays were compared. The addition of only a small amount of organoclay was sufficient to improve the thermal properties of the TLCP hybrids. Even polymers with low organoclay content (1-9 wt%) were found to exhibit much higher glass transition temperature (T_g), melt transition temperature (T_m), and initial decomposition temperature (T_Dⁱ) values than those of pure TLCP. The addition of EAB-MMT was more effective than that of Cloisite^® 30B in improving the thermal properties. The intercalation of the polymer chains in the clays was examined by wide-angle X-ray diffraction (XRD) and transmission electron microscopy (TEM).

4-(4-acetoxy-1,4-phenyleneoxytetramethyleneoxy)benzoic acid와 유기화 점토를 사용하여 in-situ 삽입 중합법 (in-situ intercalation polymerization)을 통해 열방성 액정고분자(thermotropic liquid crystalline polymer, TLCP) 나노복합체를 합성하였다. Ethyl-4-aminobenzoate(EAB) 암모늄 염 용액과 나트륨 양이온 몬모릴로나이트(Na+-MMT)와의 양이온 교환 반응을 통해 유기화 점토(EAB-MMT)를 제조하였다. 유기화 점토인 EAB-MMT와 Cloisite^® 30B를 이용하여 TLCP 복합체를 만들었으며, 두 가지 유기화 점토를 사용하여 만든 TLCP 나노 복합체의 열적 특성, 모폴로지 및 액정상을 서로 비교하였다. 단지 소량의 유기화 점토를 사용하여 TLCP 복합체의 열적 특성을 향상시켰으며, 낮은 유기화 점토 함량(1-9 wt%)을 넣은 TLCP가 순수한 TLCP보다 더 높은 유리 전이 온도(T_g), 녹음 전이 온도(T_m) 및 초기 열 분해 온도(T_Dⁱ) 값을 보였다. 열적 특성에 관해서는 EAB-MMT가 Cloisite^® 30B보다 더 효과적이었다. 고분자 사슬이 삽입된 점토는 넓은 각 X-선 회절도(X-ray diffraction, XRD)와 투과 전자 현미경(transmission electron microscopy, TEM)을 통해 관찰하였다.

Keywords: thermotropic liquid crystalline polymer, organoclay, nanocomposite, thermal property, morphology