【作者】 张春晓；

【导师】 程发； 陈宇；

【作者基本信息】 天津大学 ， 高分子化学与物理， 2011， 博士

【摘要】 本论文主要研究两亲性多臂星状聚合物聚乙烯亚胺-嵌段-聚乳酸（PEI-b-PLA）的合成、改性，超分子自组装行为及其作为客体分子载体的包裹与释放性质。具体研究内容如下：1、两亲性多臂星状聚合物PEI-b-PLA的合成、改性及表征以PEI1.2K（PEI1.2K, Mw/Mn=1.04）和PEI10K（PEI10K, Mw/Mn=2.5）为大分子引发剂，2-乙基己酸亚锡-Sn(Oct)2为催化剂，引发丙交酯(DLLA、LLA、DLA)的本体聚合，合成了一系列以PEI为核、聚乳酸(PDLLA、PLLA、PDLA)为外臂的两亲性多臂星状聚合物PEI-b-PLA。通过DSC、NMR和GPC对该类聚合物进行了表征。考察了不同反应条件（聚合温度、反应时间和催化剂的加入量）对PEI-b-PLA的引发效率、分散度及分子量的影响。分别用HCl、HBr、H2SO4、HI和CH3I对PEI-b-PLA的内核进行了季铵盐化改性，对端羟基用脂肪酸（丙酸、正戊酸和辛酸）进行了酯化封端改性。同时，采用对硝基苯甲醛对PEI上的部分胺基进行了保护，得到了不同臂密度的两亲性多臂星状聚合物PEI-b-PLA，并用NMR等分析手段进行了表征。2、两亲性多臂星状聚合物PEI-b-PLA对染料的包裹及释放性能研究PEI-b-PLA聚合物对甲基橙(MO)、曙红(EY)、荧光素钠(FS)、铬黑T(EBT)的包裹具有类似的规律：摩尔包裹量主要取决于PEI内核和臂长，内核越大，外臂越长，包裹量越大；包裹质量百分数与PEI内核关系不大，主要取决于外臂，外臂越长，包裹量越小；PEI-b-PDLLA型聚合物和PEI-b-PLLA型聚合物包裹性能差别不大；聚合物PEI-b-PLA对不同客体分子的包裹量与聚合物浓度和客体分子浓度有关，同时与客体分子的尺寸大小有关。聚合物PEI-b-PLA对客体分子的包裹是pH敏感的，包裹甲基橙的量在酸性条件下较好，当pH值为中性或碱性时，聚合物包裹量迅速下降。PEI-b-PLA聚合物分别用CH3I、HCl、 HBr、HI、H2SO4对PEI内核进行季铵盐化处理后，包裹能力大幅提高。聚合物PEI-b-PLA用正戊酸进行酯化封端后，对客体分子的包裹量下降，DLS分析表明，酯化封端后，聚合物在氯仿有机相的分散状态发生了改变，由原来的200nm变成了不到2nm。包裹客体分子后，PEI-b-PDLLA型聚合物明显比同类的PEI-b-PLLA型聚合物释放速度快；内核PEI1.2K的聚合物比内核PEI10K聚合物释放速度快，各种聚合物随着臂长的增加释放速度降低明显。更多还原

【Abstract】 This paper was mainly studied on the synthesis, modification, self-assemble behavior of theamphiphilic multi-arm star copolymer polyethylenimine-block-poly(Lactide)(PEI-b-PLA) andtheir encapsulation and release property as guest molecules delivery. The detail was asfollows:1. Synthesis, modification and characterization of the amphiphilic multi-arm star copolymerpolyethylenimine-block-poly(Lactide)(PEI-b-PLA)Catalyzed by the Tin(II)2-ethylhexanoate (Sn(Oct)2), hyperbranched polyethylenime(PEI1.2K, Mw/Mn=1.04and PEI10K, Mw/Mn=2.5）have successfully iniatiated ring-openingpolymerization of the lactide(DLLA,LLA,DLA), to obtain the amphiphilic multi-arm starcopolymer with polylactide as shell and polyethylenime (PEI) as core.These polymers werecharacterized by DSC, NMR and GPC. The influences of different reaction conditions(polymerization temperature, reaction time and the amount of catalyst) to initiation efficiency,dispersity and molecular weight were discussed.The PEI inner core of polymers (PEI-b-PLA) were quaternized with HCl、HBr、H2SO4、HIand CH3I and the PLA arms were esterified with aliphatic acid（propionic acid,valeric acid andOctylic Acid）. In the same time, the polymers (PEI-b-PLA) of different arm density were got bypart amino protection of PEI with paranitrobenzaldehyde and were characterized by NMR.2. Study of guest encapsulation and release behavior of the amphiphilic multi-arm star copolymerpolyethylenimine-block-poly(Lactide)(PEI-b-PLA)Due to the polar difference of the PLA arms and the PEI inner core, the obtained starcopolymer could act as the unimolecular micelle to encapsulate the water-soluble guests. Theirguest (MO、EY、FS and EBT）encapsulation behaviors have similar laws:Increasing the size of thehydrophilic PEI core and the hydropholic PLA arm length are two effective ways toenhance;Whereas their hydrophilic guest encapsulation capacity of the weight ration mainlydepends on the arm length and has little releration with PEI core.The longer the arm, the smallerguest encapsulation capacity. No obvious difference of their hydrophilic guest encapsulationcapacity was observed between the polymers (PEI-b-PDLLA) and the polymers (PEI-b-PLLA). Inthe same time, their hydrophilic guest encapsulation capacity related with concentration of thepolymers and the guest molecules and the size of guest molecules.The guest encapsulation capacity of PEI-b-PLA was pH sensitive, which reached the maximum loading at pH≦5.5and reduced quickly at pH≧7.0. When the PEI inner core ofpolymers (PEI-b-PLA) were quaternized with HCl、HBr、H2SO4、HI and CH3I, their hydrophilicguest encapsulation capacity increased obviously. Whereas when the PLA arms were esterifiedwith valeric acid, their hydrophilic guest encapsulation capacity decreased. It can be seen that thedecentralized state of the Polymers in chloroform changed from original200nm to less than2nmwhen characterized by DLS.Increasing the size of the hydrophilic PEI core and the hydropholic PLA arm length are twoeffective ways to slow down the realease rate of the encapsulated guest molecules. Moreover, therealease rate of the encapsulated guest molecules of the polymers (PEI-b-PDLLA) was faster thanthat of the polymers (PEI-b-PLLA).更多还原