In this work, N-hydroxyphthalimide (NHPI) was used as catalyst to cleave CH bonds in polyethylene glycol (PEG) backbones to generate carbon free radicals that reacted with the NN bonds of di-tert-butyl azodicarboxylate (DBAD) to form CN grafts (PEG-g-DBAD). Subsequently, the tert-butoxycarbonyl (-Boc) groups of PEG-g-DBAD were removed by treating with trifluoroacetic acid (TFA) to obtain hydrazino functionalized PEG (PEG-g-NHNH₂). The structure of functionalized PEG was confirmed by Fourier transform infrared spectroscopy (FTIR), ¹H nuclear magnetic resonance spectroscopy (¹H NMR), elemental analysis and size exclusion chromatography (SEC). Thermal gravimetric analysis (TGA) and differential scanning calorimetry (DSC) were applied to investigate thermal stability and crystallization properties of the functionalized PEG. The synthesized PEG-g-NHNH₂ could be used to toughen epoxy resin (EP). The results of mechanical testing and SEM images indicated that the compatibility between PEG backbones and EP has been improved due to the existing of hydrazino groups. The grafted hydrazine groups could also react with 2-bromoisobutyryl bromide (BIBB) to obtain PEG-g-BIBB which initiated the polymerization of (methyl) methacrylate (MMA) by ARGET-ATRP. Thus, we presented a methodology with high efficiency for hydrazination of PEG under mild condition, and the functionalized PEG might have many potential applications.

在这项工作中，N-羟基邻苯二甲酰亚胺（NHPI）被用作裂解聚乙二醇（PEG）主链中的C H键以生成碳自由基，该碳自由基与偶氮二羧酸二叔丁酯（DBAD）的N N键反应形成C N接枝（PEG-g-DBAD）。随后，通过用三氟乙酸（TFA）处理除去PEG-g-DBAD的叔丁氧羰基（-Boc）基团，获得肼基官能化的PEG（PEG-g-NHNH ₂）。功能化PEG的结构通过傅里叶变换红外光谱（FTIR），¹ H核磁共振光谱（¹1 H NMR），元素分析和尺寸排阻色谱法（SEC）。应用热重分析（TGA）和差示扫描量热法（DSC）研究功能化PEG的热稳定性和结晶特性。合成的PEG-g-NHNH ₂可用于增韧环氧树脂（EP）。机械测试和SEM图像的结果表明，由于存在肼基，PEG主链与EP之间的相容性得到了改善。接枝的肼基还可以与2-溴异丁酰溴（BIBB）反应，得到PEG-g-BIBB，它通过ARGET-ATRP引发了甲基丙烯酸甲酯（MMA）的聚合反应。因此，我们提出了一种在温和条件下高效PEG酰化的方法，而功能化PEG可能具有许多潜在应用。