表面引发接枝聚合法制备凹凸棒土/聚甲基丙烯酸甲酯杂化粒子的研究

PREPARATION OF ATTAPULGITE/PMMA HYBRID PARTICLES VIA SURFACE-INITIATED GRAFT POLYMERIZATION

将γ-氨丙基三乙氧基硅烷(APTES)接枝到凹凸棒土(AT)表面,制得表面键合伯氨基的改性粒子AT-APTES;通过AT-APTES表面的伯氨基和过硫酸铵(APS)构成氧化-还原引发体系,采用无皂乳液法实现甲基丙烯酸甲酯(MMA)在AT表面接枝聚合,制得最高接枝率为29.4%的杂化粒子AT-g-PMMA;采用红外光谱(FTIR)、拉曼光谱(Raman)、透射电镜(TEM)以及热失重分析(TGA)等方法对杂化粒子AT-g-PMMA进行了表征;研究了主要配方及工艺条件对表面引发接枝聚合接枝率的影响.结果表明,伯氨基-过硫酸铵引发体系可以有效引发MMA在AT表面接枝聚合,由于引发点位于AT表面,故接枝率较高.本研究体系适宜的温度为65℃,单体MMA用量为水质量的6%,APS用量为单体质量的1%,此工艺条件下可有效减小均聚反应对接枝聚合反应的影响.先接枝到AT表面的聚合物对后续的接枝聚合反应产生抑制作用,接枝率越高,抑制作用越大.

γ-Triethoxysilylpropylamine(APTES) was grafted onto the surface of attapulgite rod crystals to get the modified particles AT-APTES,and then a redox initiating system was constructed with the primary amino groups on the surface of AT-APTES particles and the ammonium persulphate in the solution,the 'surface-initiated graft polymerization' of methyl methacrylate was realized and the hybrid particles AT-g-PMMA with a high grafting degree of 29.4% were obtained at last.The hybrid particles were characterised by FTIR,Raman,TEM and TGA.The results showed that APTES was grafted onto the surface of attapulgite rod crystals and PMMA was grafted from the surface of AT-APTES particles successfully.The effects of some factors on the grafting polymerization of MMA were investigated mainly.The experimental results show that the optimal temperatures is of the 'surface-initiated graft polymerization' is 65 ℃ and the decrease of grafting degree at higher temperatures is due to the heat decomposition of ammonium persulphate.The quantity of APS which accounted for 1 wt% of the monomer mass was chosen as the most reasonable amount,and the appropriate monomer concentration 6 wt% of the water mass.In addition,the grafted polymer layer would restrain subsequent grafting polymerization and polymerization location would transfer from the surface of attapulgite to half polymer micelle with higher temperature and excessive monomer or ammonium persulphate.