在交联聚合物微球GMA/MMA表面接枝固载聚乙二醇的研究

以乙二醇二甲基丙烯酸酯为交联剂,采用悬浮聚合方法,制备了甲基丙烯酸缩水甘油酯(GMA)和甲基丙烯酸甲酯(MMA)的交联微球GMA/MMA.使用Lewis酸催化剂,通过环氧键的开环反应,将聚乙二醇(PEG)偶合接枝在交联微球GMA/MMA表面,实现了PEG的固载化,制得了三相相转移催化剂PEG-GMA/MMA.重点考察了各种因素对PEG接枝固载过程的影响,并研究了反应机理.实验结果表明,以交联微球GMA/MMA为载体,可以顺利地实现PEG的固载化,这是制备PEG三相相转移催化剂的简捷途径.实验发现,Lewis酸也能催化环氧键的开环反应,而且比质子酸的催化更加有效.溶剂的极性对偶合接枝反应的影响较大,采用极性大的溶剂有利于PEG的接枝固载.偶合接枝体系中,过高的催化剂用量会导致PEG双端羟基参与接枝反应,使载体表面大分子之间发生附加交联,不利于PEG的接枝固载.在适宜的反应条件下,接枝微球PEG-GMA/MMA表面的PEG接枝度可达0.20 g/g.

STUDIES ON GRAFTING AND IMMOBILIZING POLYETHYLENE GLYCOL ON POLYMERIC MICROSPHERES GMA/MMA

The copolymerization of glyceryl methacrylate (GMA) and methyl methacrylate (MMA) was performed in a suspension polymerization system using ethylene glycol dimethacrylate (EGDMA) as crosslinker,resulting in the crosslinked microspheres GMA/MMA. Via ring-opening reaction,polyethylene glycol (PEG) was grafted onto the surfaces of microspheres GMA/MMA in the coupling graft manner,the immobilization of PEG was realized,and a kind of phase-transfer catalysts PEG-GMA/MMA,namely,triphase catalyst,was prepared.The effects of various factors on the grafting reaction of PEG were studied,and the reaction mechanism was investigated.The experimental results show that the immobilization of PEG on microspheres GMA/MMA can be conducted favorably,and this is a shortcut route to prepare triphase catalysts of PEG.It is found that Lewis catalysts are more effective than protonic acids for the ring-opening reaction of epoxy groups.The polarity of the solvents affects the coupling graft reaction between PEG and microspheres GMA/MMA greatly,and to use the solvents with higher polarity is advantageous to the graft reaction.In the graft reaction system,the additional crosslinking will be produced between the micromolecules on microspheres GMA/MMA if the used amount of the catalyst is excessive,and the additional crosslinking is adverse to the coupling graft of PEG.Under the suitable conditions,the PEG graft degree of the grafted microspheres PEG-GMA/MMA can get up to 0.20 g/g.