受限空间内聚苯乙烯微粒的制备

Preparation of Polystyrene Nanospheres in Confined Space

以(N,N-二甲氨基-4-吡啶)五氰合铁(II)封端的聚氧丙烯聚氧乙烯共聚物(EPE-Fe)与苯乙烯在水中自组装形成纳米体系(EPE-Fe-St),在纳米尺度受限空间内进行了苯乙烯自由基聚合,制备了聚苯乙烯微球(EPE-Fe-PS).用Fe3+对自组装体系的纳米球壳进行固化后形成Fe-EPE-Fe-St体系,聚合后也制备了聚苯乙烯微球(Fe-EPE-Fe-PS).研究结果表明,制备了粒径为60～200 nm的不同粒径单分散聚苯乙烯微球,聚合温度对纳米Fe-EPE-Fe-St体系粒径影响较小,而对EPE-Fe-St体系较大.在受限空间内苯乙烯的自由基聚合可得到数均分子量超过70万的聚苯乙烯;自组装体系中引发剂量增多使聚苯乙烯分子量下降,聚合温度上升也使分子量下降,而增加自组装的EPE-Fe用量可增加聚苯乙烯的分子量.两种受限条件下的聚苯乙烯微球的玻璃化转变温度(Tg)在90～135℃之间,纳米反应器壳层的硬化提高了聚苯乙烯微球的Tg.

The poly（ethylene glycol）-b-poly（propylene glycol）-b-poly（ethylene glycol） terminated with pentacyano（4-（dimethylamino）-pyridine） ferrate （EPE-Fe） complex surfactant was synthesized and was used to be self-assembled with styrene （St） in water to form a nano-reactor （EPE-Fe-St）. The free radical polymerization of styrene occurred in the confined space in nanosize. And the polystyrene nanospheres （EPE-Fe-PS） were prepared in the nano-reactor. Furthermore, ferric ion was used to cure the shell of the EPE-Fe-St to form a hardened nano-reactor （Fe-EPE-Fe-St）. The styrene polymerization was also arisen in the nano-reactor to form polystyrene nanospheres （Fe-EPE-Fe-PS） with a hardened shell. The results of molecular weight and morphology of polystyrene nanospheres show that the various size of monodispersed polystyrene nanospheres in 60--200 nm have been obtained in the confined nanospace. The effect of polymerization temperature on the size of self-assembled EPE-Fe-St is remarkable, and on the size of the Fe-EPE-Fe-St is slight. The higher molecular weight of the polystyrene has achieved more than 700000 in the confined space. In the self-assembled nano-reactor, the molecular weight of PS decreases with increase of initiator content in St solution and enhancement of polymerization temperature, and increases with augment of EPE-Fe content in water. The glass transition temperature （Tg） of the polystyrene nanospheres prepared in two kinds of the confined space are in the range of 90- 135 ℃. The Tg of polystyrene nanosphere is enhanced obviously after hardening the shell of nano-reactor whether the hardening shell arises before or after the polymerization.