温敏性Pluronic-b-poly((ε-caprolactone)-co-(6-(benzyl-oxycarbonylmethyl)-ε-caprolactone))的合成和性能研究

Synthesis and Properties of Thermo-sensitive Amphiphilic Pluronic-b-poly((ε-caprolactone)-co-(6-(benzyl-oxycarbonylmethyl)-ε-caprolactone))

以聚乙二醇99-b-聚丙二醇69-b-聚乙二醇99(PEO99-b-PPO69-b-PEO99 Pluronic F127)为大分子引发剂,引发己内酯(CL)和6-乙酸苄酯-己内酯(BCL)开环聚合得到一系列不同BCL含量的两亲性嵌段共聚物Pluronic-b-poly((ε-caprolactone)-co-(6-(benzyl-oxycarbonylmethyl)-ε-caprolactone))(Pluronic-b-P(CL-co-BCL)).通过核磁共振,红外光谱和凝胶渗透色谱确定共聚物的结构、组成和分子量及其分布.热重分析、X射线衍射和差示扫描量热法的结果表明,聚合物的热稳定性及结晶性均可通过调控共聚物中BCL的含量进行调控.通过乳化溶媒挥发法制备聚合物胶束,并用荧光光谱,扫描电镜和粒径分析仪研究聚合物胶束的形成,形态和大小,结果表明胶束呈现规整球形且分布较为均匀,均具有较小的临界胶束浓度且受聚合物中BCL比例的影响;由光散射的结果看出,随着BCL的引入,Pluronic-b-P(CL-co-BCL)胶束粒径呈现出可逆的温度敏感性变化.

In this paper,a series of amphiphilic block copolymers Pluronic-b-poly(ε-caprolactone-co-benzyl-oxycarbonylmethyl-ε-caprolactone)(Pluronic-b-P(CL-co-BCL)) were synthesized successfully via ring-opening polymerization(ROP) of ε-caprolactone(CL) and 6-(benzyl-oxycarbonylmethyl)-ε-caprolactone(BCL) using stannous octoate as the catalyst(weight ratio:0.5‰) and PEO99-b-PPO69-b-PEO99(Pluronic F127) as macroinitiator.1H NMR,GPC and FT-IR were employed to determine the structure,composition,molecular weight and molecular weight distribution.The result of 1H NMR showed the content of BCL in the copolymers was less than the theoretical value,which may be attributed to the low reactivity of BCL due to the steric hindrance of Bn substituent on the δ position of CL.The number-average molecular weight by GPC was different from the value calculated by 1H NMR,it may be attributed to the hydrodynamic volume of the copolymers being different from that of the poly(styrene) as the GPC calibration in THF.The thermal properties of the copolymers were evaluated by TGA,DSC and XRD.The results indicated that the stability and the crystallinity of the copolymers could be adjusted by the content of the BCL.Due to the BCL units in the copolymers reduced the regularity of the PCL chain and intensively disrupted its crystallinity and the steric hindrance effect of BCL trammeled the movement of the PCL chain,the melting point(Tm) of CL segment in copolymer shifted down and the glass transition temperature(Tg) of copolymer increased with the increase of the content of BCL respectively.Emulsion/solvent evaporation technique was employed to prepare the polymeric micelle solution.The formation,size and morphologies of the micelles in aqueous solution were studied by fluorescence spectroscopy,TEM and DLS,the results demonstrated that the micelles were spherical spheres with narrow distribution,the copolymer had low critical micelles concentration(CMC) and depended on the content of BCL in the copolymer.Moreover,DLS results showed that the Pluronic-b-P(CL-co-BCL) had a reversible thermosensitivity due to the introduction of BCL.