Synthetic routes and properties of polyparabanic acid were studied. As model compounds, N,N'-dimethylparabanic acid and N,N'-diphenylparabanic acid were prepared by the reaction of N,N'-dlmethyl urea and N,N'-diphenyl urea, respectively, with oxalyl dichloride in the presence of pyridine as a catalyst. The N-substituted parabanic acids were characterized by IR, ¹H-NMR, Mass spectroscopy and elemental analysis. Various polyureas were synthesized via polyaddition reaction of 1,6-hexamethylene diisocyanate with aliphatic or aromatic diamines In DMF solution. Then, the polyureas were treated wlth oxalyl dichloride to yield polyparabanic acids. Formation of polyparabanic acid was confirmed by the appearance of IR absorption at 1730 cm^-1 and 1780 cm^-1 which were assignable to the carbonyl stretching peaks of 5-membered ring in polyearabanic acld. Inherent viscosities of the obtained polyparabanic acids were in the range of 0.15∼0.48 dL/g and the TGA data revealed 10% weight losses at 370∼458℃ whereas those of polyureas were in the range of 0.29∼0.71 dL/g and 235∼301℃ respectively.

Diisocyanate와 diamine으로 부터 중합된 polyurea를 거쳐 polyparabanic acid를 합성하는 방법이 연구되었다. 모델반응으로 N,N'-dimethylurea와 N,N'-diphenylurea를 pyrldine존재 하에 oxalyl dichloride와 반응시켜 각각 N,N'-dimethylparabanic acid와 N,N'-diphenylparabanic acid를 합성하고 IR, ¹H-NMR, Mass 스펙트럼과 원소분석으로 구조를 확인하였다. Hexamethylene diisocyanate (HDI)와 aliphatic 또는 aromatic diamine을 DMF 중에서 상온 반응시켜 다양한 구조의 polyurea를 합성하였다. 이때 합성한 polyurea를 무수(無水) dichloroethane용매에서 피리딘을 촉매로 oxalyl dichloride와 반응시켜 polyparabanic acid를 합성하였다. IR 스펙트럼에서 polyurea의 3300cm^-1 (NH)와 1650cm^-1 (C=0)의 흡수대가 반응후 사라지고 parabanic acid의 특성 흡수대가 1730cm^-1와 1780cm^-1에서 나타나는 것으로 보아 polyparabanic acid가 합성된 것을 확인할 수 있었다. Polyparabanic acid는 diamlne의 구조에 따라 본질점도가 0.15∼0.48 dL/g이었으며 TGA 분석에서는 10% 중량감소 온도가 370∼458℃ 사이에서 관찰되었다.

Keywords: polyparabanic acid; polyurea; thermal resistance