亲水性含环氧基磁性聚合物微球的制备与性能表征

选择甲酰胺作磁性Fe3O4微晶的分散剂,通过设计反相悬浮聚合体系,合成了粒径分布窄、球状亲水性含环氧基磁性聚合物(MGM).利用扫描电子显微镜(SEM)、红外光谱(FT-IR)、X射线粉末衍射仪(XRD)、振动样品磁强计(VSM)和低温N2吸附以及化学分析方法对聚合物进行了性能表征.结果表明,合成的MGM呈球形,且粒度分布较窄,粒径为0.13~0.28 mm的粒子占91%;甲酰胺分散Fe3O4,微晶表面的亲水性进一步增强,单体甲基丙烯酸缩水甘油酯和N,N′-亚甲基双丙烯酰胺交联共聚生成的胶粒能够包埋Fe3O4微晶形成胶核,胶核聚集形成均匀、稳定的MGM微球.MGM中Fe3O4含量为6.17%时,比饱和磁化强度σs达6.5 emu/g;其比表面积、平均孔径和孔容分别为117.6 m2/g,15.6 nm和0.46 cm3/g,表面环氧基团含量为0.53 mmol/g.MGM借助自身的活性环氧基团在十分温和的条件下共价偶联青霉素酰化酶(penicillin G acylase EC 3.5.1.11,简称PGA),制备的固定化酶在37℃下催化水解青霉素G钾生成6-氨基青霉烷酸(6-APA)的表观活性达502IU/g,并且在使用过程中没有出现磁聚集现象.

PREPARATION AND CHARACTERIZATION OF HYDROPHILIC MAGNETIC POLYMER MICROSPHERES CONTAINING OXIRANES

Spherical hydrophilic magnetic polymer(MGM) containing oxiranes was synthesized by designing the inverse suspension polymerization system in which formamide was employed as the dispersant of magnetic Fe_3O_4 microcrystal.Scanning electron microscopy(SEM),FT-IR spectroscopy,X-ray diffraction(XRD),vibrating sample magnetometer(VSM),low temperature N_2 adsorption and chemical analysis methods were used to characterize the properties of the polymer.The results showed that MGM had good spherical shape and narrow size distribution,and the particles with diameters ranging from 0.13 mm to 0.28 mm were about 91 wt%.The surface hydrophilicity of Fe_3O_4 microcrystal was improved by formamide dispersing treatment.The gel particles made by the copolymerization of glycidyl methacrylate and N,N′methylene bisacrylamide could encapsule Fe_3O_4 microcrystal to produce colloid cores,and uniform and stable MGM microspheres were formed by the conglomeration of the colloid cores.The saturated magnetization of MGM reached 6.5 emu/g while the Fe_3O_4 content were 6.17%.The specific surface area,average pore diameter and pore volume and oxirane content was 117.6 m~2/g,15.6 nm,0.46 cm~3/g and 0.53(mmol/g,)respectively.Penicillin G acylase(PGA) was immobilized on MGM microspheres by the covalent coupling between the reactive oxiranes of MGM and amino groups of PGA under mild conditions.The apparent activity of the immobilized PGA reached 502 IU/g for hydrolyzing penicillin G potassium to 6-aminopenicillanic acid at 37℃.There was no agglomeration of the magnetic particles in applications .