Reevaluation of Tetrahydrophthalic Anhydride as an End Cap for Improved Oxidation Resistance in Addition Polyimides
作者:Mary Ann B. Meador、Aryeh A. Frimer、J. Christopher Johnston
DOI:10.1021/ma0353078
日期:2004.2.1
Several substituted 1,2,3,6-tetrahydrophthalic anhydride end caps, including the 3-phenyl, 3-methoxy, 3-trimethylsilyloxy, and 3,6-diphenyl analogues, were synthesized via the Diels−Alder condensation of the corresponding butadienes and maleic anhydride. These anhydrides, as well as the commercially available 3-hydro and 4-methyl analogues, were each ground up together with methylenedianiline in a
几个取代的1,2,3,6-四氢邻苯二甲酸酐端基,包括3-苯基,3-甲氧基,3-三甲基甲硅烷氧基和3,6-二苯基类似物,是通过相应丁二烯和丁二烯的Diels-Alder缩合合成的。马来酸酐。将这些酸酐以及可商购的3-氢和4-甲基类似物分别与亚甲基二苯胺以2:1的比例一起研磨,并逐渐从204加热到371°C,并进行热解和NMR。一般而言,在较低温度范围内观察到通过单酰亚胺到双酰亚胺的转变,然后是交联和芳构化之间的竞争。我们相信,这种竞争会产生很大比例的芳香产品,伴随着交联的相对量的降低,并且导致四氢邻苯二甲酸端基封端的聚酰亚胺的热氧化稳定性的提高以及它们的易碎性。在惰性气氛下四氢邻苯二甲酰亚胺的热解显着降低了芳构化的量。因此,芳香化的机制是一种氧化机制。