以直链淀粉为起始物,先通过羟丙基化反应得到羟丙基淀粉(HPS),然后以三氟甲磺酸亚锡(Sn(OTf)2)为催化剂,通过接枝共聚反应合成了聚己内酯与HPS的刷形接枝共聚物HPS-g-PCL.考察了反应温度和反应时间对产物接枝率的影响,并采用红外光谱(FT-IR)和核磁共振谱(1H NMR)对接枝产物的分子结构进行了表征.结果表明,Sn(OTf)2是一种比Sn(Oct)2更为理想的催化剂;产物的接枝率随反应时间的延长或反应温度的升高而不断增大;随着接枝率的提高,接枝聚合物膜的表面接触角也逐渐增大.透射电子显微镜(TEM)和原子力显微镜(AFM)观察结果表明,接枝聚合物在选择性溶剂水或者丙酮中能自组装形成核壳结构的球状胶束.HPS-g-PCL胶束对药物布洛芬表现出较高的负载效率和良好的可控释放行为,接枝率越高,药物缓释速率越慢,但释放量都高于80％.
With amylose as the starting material,hydroxypropyl starch (HPS) was first prepared viahydroxypropylation reaction.Then,by using tin (Ⅱ) trifluoromethanesulfonate (Sn (OTf)2) as the catalyst,graft copolymer HPS-g-PCL with brush-like structure between HPS and caprolactone was successfully synthesized via ring opening polymerization.The effect of reaction temperature and reaction time on the graft yield was investigated,and the structure of HPS-g-PCL was characterized by infrared spectroscopy(FT-IR) and nuclear magnetic resonance (1H NMR).The results indicate that Sn(OTf)2 is a more efficient catalyst than stannous octoate.The graft yield increased as the reaction time or temperature increased.The results of surface contact angle show that the hydrophilicity of the graft copolymer decreased gradually as the grafting yield increased.Transmission electron microscopy (TEM) and atomic force microscopy (AFM) observations demonstrate that the graft copolymer can self-assemble into spherical micelles in the selective solvents.By using ibuprofen as the model drug,the drug release behavior of the micelles was investigated,indicating that the drug ibuprofen can be well loaded into the micelles,and a controlled-release behaviour was found with the loaded micelles.The sus tained release rate of the drug in the micelles,which was over 80 ％,decreased with the increasing of graft yield.
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