A series of new semi-rigid polyspiroacetals with flexible side groups was prepared by interfacial polycondensation reactions of 4,4'-bis-(p-aminophenoxy)- dibenzalpentaerythritol with 2,5-dialkoxyterephthaloylchlorides having different alkoxy side chains. The resulting polymers showed improved solubilities in common organic solvents such as N,N-dimethylacetamide, N-methyl-2-pyrrolidinone, m-cresol, etc. All polymers dissolved in these solvents could be cast into good quality films. The glass transition temperature (T_g) of the polymers decreased with increasing length of alkoxy substituent from 177℃ to 103℃. It was also found that the polymer decomposition starts in the temperature range of 270∼320℃, and their residual weight was in the range 27∼36%, depending upon alkoxy side chain lengths. According to X-ray diffraction studies, all polymers were found to be nearly amorphous due to flexible ether linkage in polymer backbone. The solution-cast film of PSA-Ⅱ-4 having butoxy side groups showed tensile strength of 43 MPa and Young's modulus of 2000 MPa.

중합체 골격에 스피로아세탈을 함유하고 에테르기와 알콕시 곁사슬을 갖는 방향족 폴리아미드를 2,5-dialkoxyterephthaloyl chlorides와 4,4'-bis(p-aminophenoxy)dibenzalpentaerythritol로부터 저온 계면중합시켜 합성하였다. 이 중합체들은 N,N-dimethylacetamide, N-methyl-2-pyrrolidinone, m-cresol 등에 용해되었으며, 유리전이온도는 알콕시 곁사슬 길이가 증가함에 따라 177℃에서 103℃ 까지 감소하는 경향을 보였다. 또한 이들 중합체들은 272∼321℃에서 분해가 시작되었고, 800℃에서의 잔존질량은 27∼36%이었다. 모든 중합체는 결정도가 낮거나 또는 무정형임이 광각 X-선 산란패턴에서 나타났다. 곁사슬이 부톡시기로 치환된 중합체의 기계적 성질을 조사한 결과 인장강도가 43MPa, 인장탄성률이 2000MPa로 나타나 기존의 엔지니어링 플라스틱 수준과 유사함을 알 수 있었다.

Keywords: spiroacetal; flexible side chains; aromatic polyamides; semi-rigid backbone