环氧乙烷／四氢呋喃共聚醚的热氧降解机理

Thermooxidation Mechanism of the Co-polyether (EO/THF)

应用电子自旋共振（ＥＳＲ）、核磁共振（ＮＭＲ）及傅里叶红外光谱（ＦＴ－ＩＲ）技术研究了环氧乙烷／四氢呋喃共聚醚在空气中加热降解的机理．发现共聚醚的热氧降解首先发生在醚键的α碳上，采用苯基叔丁基硝酸灵作捕捉剂，用ＥＳＲ成功地捕捉到α碳上脱氢后形成的碳自由基和氧自由基．用ＦＴ－ＩＲ跟踪检测了共聚醚在老化过程中的结构变化．结合－维核磁共振波谱及二维化学位移相关谱对降解产物进行了结构表征和归属，揭示了共聚醚热氧降解的机理．

Theamooxidation mechanism of co-polyether (ethyleneoxide-terahydrofuran) at 90℃ in air was determined by electron spin resonance (ESR), FT-IR and NMR (including 1H , 13C, Dept and 2D COLOC NMR). The initial degradation site was found tO be at the α-carbon of ether bond. Two faee radicals which derived from dehydrogenation and oxygen addition were successfully detected by spin-trapping technique which used α-phenyl-N-tert-butylnitrone (PBN) as spin trap. FT-IR was used to follow the structural changes of the co-polyether (EO/THF) during thermooxidation, the spectrometric results indicated that there were many carbonyl groups accompanying few alkene groups and existed no aldehyde, no carbonylic acid in the products . 1D NMR, combined with 2D COLOC NMR were effectively utilized to analyze the structure of there products, over ten sorts of segmental structure were characterized. Thermooxidation mechanism was therefore schematically proposed.