光敏性单分散核-壳树莓状PSt/PAM微球制备

PREPARATION OF PHOTOSENSITIVE MONODISPERSE CORE-SHELL RASPBERRY-LIKE PSt/PAM MICROSPHERES

采用分散聚合两步加料法,在成核期后向反应体系加入光引发转移终止剂(photo-iniferter)单体2-N,N-二乙基二硫代氨基甲酰氧基乙酸β-甲基丙烯酰氧基乙酯(MAEDCA)制备了核-壳单分散光敏性聚苯乙烯(PSt)微球;进一步,在甲醇介质中,利用光敏性微球在紫外光辐照下引发单体丙烯酰胺(AM)进行表面沉淀接枝聚合,制得了表面亲水、树莓状(raspberry-like)PSt/PAM微球.采用SEM及TEM观察了所得微球的结构和形貌,FTIR、UV-Vis、1H-NMR及XPS分析表明微球的photo-iniferter基团含量随MAEDCA加入量增大而提高,同时补加一定量的MAEDCA、St、AIBN、甲醇及水时所得光敏性PS微球单分散性最好;微球表面接枝PAM后变得亲水并可大量吸附Ag纳米粒子.

Monodisperse core-shell microspheres of polystyrene（PSt） contained photo-iniferter moieties were prepared first by a two-stage dispersion polymerization in which β-methacryloxylethyl 2-N,N-diethyldithiocarbamylacetate（MAEDCA） was charged into a reaction system after nucleation.Subsequently,raspberry-like PSt/poly acrylamide（PAM） particles were achieved by an ultraviolet light-induced surface grafting polymerization of acrylamide（AM） using the as-prepared photosensitive PSt particle as an initiator,and in a medium of methanol which is not a good solvent for the grafted chain of PAM.The morphology and core-shell structure of as-produced particles were revealed by scanning electron microscope（SEM） and transmission electron microscope（TEM） observation.Fourier transform infrared spectroscopy（FTIR）,ultraviolet and visible absorption spectroscopy（UV-Vis）,nuclear magnetic resonance（1H-NMR） and X-ray photoelectron spectroscopy（XPS） analyses demonstrated that the degree of incorporated photo-iniferter moieties on particle surface improved with the increase of MAEDCA added in system.In addition,it is advantageous to achieve narrowly distributed microspheres when a mixture of MAEDCA,styrene（St）,2,2′-azodiisobutyronitrile（AIBN）,methanol（MeOH） and H2O were introduced into the system in the second stage of dispersion polymerization.The surface of PSt particles grafted with PAM became hydrophilic,and on which Ag nano-particles were attached readily.