三嵌段共聚物PS-PHB-PS的原子转移自由基聚合

为了克服聚β-羟基丁酸酯(PHB)的弱点, 得到性能良好的新材料, 本文利用原子转移自由基聚合方法, 以Br-PHB-Br为大分子引发剂, 苯乙烯为单体, 在CuBr/N,N,N′,N″,N″-五甲基–二乙基三胺(PMDETA)催化体系作用下合成了一种新的三嵌段共聚物聚苯乙烯-聚β-羟基丁酸酯-聚苯乙烯(PS-PHB-PS). 共聚物的链结构利用¹H NMR和¹³C NMR进行了表征, 分子量特性和链段组成利用凝胶渗透色谱(SEC)方法进行了测定. 聚合物的分子量随单体转化率的增加而线性增加, 分子量分布指数相对较窄. 这些特征都满足原子转移自由基活性聚合的理想要求. 所得到的共聚物PS-PHB-PS具有较好的生物相容性, 与PHB相比具有良好的耐热性.

Atom Transfer Radical Polymerization of PS-PHB-PS Triblock Copolymers

To overcome the drawback of poly(β-hydroxybutyrate) (PHB) and obtain some useful new materials based on PHB, a new ABA type triblock copolymer of PS-PHB-PS has been successfully synthesized by ATRP (atom transfer radical polymerization) method with Br-PHB-Br as macroinitiator, styrene as monomer and CuBr/PMDETA (N,N,N',N",N"-pentamethyldiethylenetriamine) as the catalyst system. The chain architectures of the triblock copolymers were confirmed by the ¹H NMR and ¹³C NMR spectra. SEC (size exclusion chromatography) analysis was used to estimate the molecular weight characteristics and the lengths of the PHB and PS blocks of the copolymers. The molecular weight M_p was increased linearly with conversion and these triblock copolymers showed relatively narrow polydispersities, indicating that the system displayed characteristics of a living radical polymerization. The obtained triblock copolymers had good biocompatibility and better thermal properties than those of PHB homopolymer.