N-Hydroxyphthalimide catalyzed hydrazination of polyethylene glycol
In this work, N-hydroxyphthalimide (NHPI) was used as catalyst to cleave C H bonds in polyethylene glycol (PEG) backbones to generate carbon free radicals that reacted with the N N bonds of di-tert-butyl azodicarboxylate (DBAD) to form C N 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-NHNH 2 ). The structure of functionalized PEG was confirmed by Fourier transform infrared spectroscopy (FTIR), 1 H nuclear magnetic resonance spectroscopy ( 1 H 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-NHNH 2 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.
危险品化学品经营许可证（带存储）