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用偶联剂γ-(甲基丙烯酰氧)丙基三甲氧基硅烷(KH-570)对微米级硅胶进行了表面化学改性,采用溶液聚合法,在改性硅胶微粒表面接枝丙烯腈(AN),制备了接枝微粒PAN/SiO_2.用盐酸羟胺对接枝PAN进行偕胺肟 (AO)化转变,制得了接枝有偕胺肟树脂(PAO)的复合型功能微粒PAO/SiO_2.采用红外光谱(FTIR)、热失重(TGA)及扫描电子显微镜(SEM)等测试技术,对接枝微粒PAN/SiO_2以及功能微粒PAO/SiO_2进行了表征,考察了制备条件对AN的接枝聚合过程及对PAN的偕胺肟化转变过程的影响规律.结果表明,适宜的接枝聚合条件为:引发剂质量分数为1.5%,反应温度为75 ℃.接枝聚合5 h可制得接枝度为0.14 g/g的接枝微粒PAN/SiO_2.受偕胺肟基团空间位阻的影响,PAN的偕胺肟化转变反应不能进行彻底,适宜的PAN/SiO_2偕胺肟化转变反应条件为:介质pH值为6～7,温度70 ℃,反应时间4 h.所制得的功能微粒PAO/SiO_2腈基转化率约为78%.

Micron-sized silicon particles were chemically surface-modified with coupling agent KH570,and the grafted particles PAN/SiO_2 were obtained. The graft polymerization of acrylonitrile(AN) on the surfaces of particles PAN/SiO_2 was performed in a solution polymerization system. The transformation reaction of nitrile groups of the grafted PAN to amidoxime groups(AO) was conducted with hydroxylamine hydrochloride as reagent in the presence of Na_2CO_3,resulting in functional composite particles of PAO/SiO_2,on which poly(amidoxime) macromolecules were chemically anchored. The two kinds of particles were characterized with FTIR,TGA and SEM methods. The effects of the main factors on the graft polymerization of AN and on the amidoxime transformation reaction of the grafted PAN were examined. The experimental results show that in the graft polymerization process,the suitable amount of initiator used is 1.5% of monomer mass,and the appropriate reaction temperature is 75 ℃. As the graft polymerization is carried out for 5 h under the proper conditions,the grafted particles PAN/SiO_2 with a grafting degree of 0.14 g/g can be obtained. The amidoxime transformation reaction can not be carried out completely due to the steric hindrance of amidoxime groups. The optimal reaction conditions for the amidoxime transformation reaction of the grafted PAN are as follows:pH value in a range of 6～7,reaction temperature 70 ℃ and reaction time 4 h. Under the appropriate conditions,the functional particles of PAO/SiO_2 with a nitrile group conversion ratio of 78% can be obtained.