受限空间内聚苯乙烯微粒的制备

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(T_g)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T_g.

Preparation of Polystyrene Nanospheres in Confined Space

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 Tgof polystyrene nanosphere is enhanced obviously after hardening the shell of nano-reactor whether the hardening shell arises before or after the polymerization.