多种谱学方法研究环氧乙烷/四氢呋喃共聚醚的热氧降解  

Spectrometric Investigation on the Thermooxidative Degradation of Ethylene Oxide and Tetra-hydrofuran Co-polyether

作　　者：罗善国[1] 陈福泰[1] 谭惠民[1] 张建国[2] 罗运军[1] 

机构地区：[1]北京理工大学化工与材料学院高分子材料研究室,北京100081 [2]中国科学院长春应用化学研究所,长春130022

出　　处：《分析化学》2001年第5期516-521,共6页Chinese Journal of Analytical Chemistry

基　　金：国家"8 63"计划资助课题 (No .863 715 0 11 0 0 90 )

摘　　要：采用电子自旋共振 (ESR)、傅里叶变换红外光谱 (FT IR)和多种核磁共振 (NMR)技术研究了环氧乙烷 /四氢呋喃共聚醚的热氧降解 ,表征了近 2 0种产物结构碎片 ,并对EO和THF两种链节的降解作了定量讨论。共聚醚的氧化降解发生在醚键氧碳上 ,遵循自由基氧化机理 ,最后形成大量的甲酸酯、碳酸酯等酯类以及甲基、亚甲二氧基和醇 ,此外还检测到过氧化氢和半缩甲醛结构。分析表明共聚醚中THF链节的降解程度明显大于EO链节 ,而且降解容易发生在两种链节交替连接处。抗氧剂 2 ,6 二叔丁基 4 甲基酚 (BHT)不仅降低了共聚醚的氧化降解程度 ,还改变了降解产物的结构分布 ,显著抑制了碳酸酯和亚甲二氧基结构的生成 。The thermooxidative degradtion of ethylene oxide and tetra-hydrofuran (EO-THF) co-polyether has been studied by electron spin resonance (ESR), Fourier transform infrared (FT-IR) and nuclear magnetic resonance (NMR) spectroscopy. The initial degradation site was found to be at the a-carbon of the ether bond. Two free radicals which derived from dehydrogenation and oxygen addition were successfully detected by spin-trapping technique which used alpha -phenyl-N-tert-butyl nitrone(PBN) as spin trap. Both FT-IR and NMR have been used to follow structural changes of the copolyether during degradation. Nearly 20 product fragments including formate, carbonate, methyl, alcohol, methylene-dioxy, hydroperoxide and semiformal have been characterized by D-1 and D-2 NMR. The thermooxidtion of co-polyether preferred to occur on the THF units especially at the alternating linkage of EO and THF. Antioxidant (BHT) not only retarded the thermooxidation but also modified the degradation products with less ester and methylene-dioxy groups hut more hydroxyl and methyl groups.

关 键 词：共聚醚 热氧降解 电子自旋共振 傅里叶变换红外光谱 核磁共振 自由基氧化 环氧乙烷 四氢呋喃 

分 类 号：O631[理学—高分子化学]