【作者】 石云峰；

【导师】 朱新远； 颜德岳；

【作者基本信息】 上海交通大学 ， 高分子化学与物理， 2010， 博士

【摘要】 超支化聚合物是一类具有准球形结构的高度支化大分子,具有大量的末端官能团和内部空腔。超支化聚合物结构独特、制备简单,因此日益受到人们的重视。如今,超支化聚合物的合成、结构表征、功能化改性等技术已经日趋成熟和完善,超支化聚合物的应用也逐渐兴起。人们在超支化聚合物自组装、药物控制释放、纳米封装、基因转染等许多领域进行了广泛的研究,但是超支化聚合物的一些应用领域还有待开发和完善。本文在综合前人有关超支化聚合物工作的基础上,在超支化聚合物的功能化方面做了一些新的探索和研究。基于本课题组有关官能团非等活性单体对合成超支化聚合物的策略,我们制备了超支化聚酰胺胺(HPAMAM),然后对HPAMAM进行化学改性或通过非共价相互作用构筑不同类型的纳米反应器并用于制备CdS量子点和Au、Ag等金属纳米晶体;利用超支化聚乙烯亚胺(HPEI),我们原位制备了有机-无机纳米杂化磁性非病毒基因载体,并研究了其磁转染性能;我们还合成了棕榈酰氯封端的两亲性超支化聚酰胺胺(HPAMAM-PC),并考察了HPAMAM-PC对CdTe和Au纳米晶体的封装性能,分别实现了CdTe和Au纳米晶体在水/氯仿界面的自组装。具体研究内容和主要结论概括如下:1.以超支化聚合物作为纳米反应器制备无机纳米晶体合成了端基为酯基的超支化聚酰胺胺,并以其作为纳米反应器制备了粒径小且尺寸分布均一的CdS量子点。我们考察了Cd2+/S2-摩尔比、反应温度、反应pH值和陈化时间等对CdS量子点光学性能的影响,并用UV-Vis、PL、TEM和FT-IR等对所制备的纳米复合物进行了表征。2.以两亲性超支化聚合物作为单分子纳米反应器在两相体系中制备无机纳米晶体发展了一种利用两相体系制备单分散、尺寸分布均一CdS量子点的新方法。在两相体系中,用氯仿和水分别作为十六烷基酰氯封端的超支化聚酰胺胺(HPAMAM-PC)和Cd(CH3COO)2/Na2S的溶剂。HPAMAM-PC具有亲水性的超支化聚酰胺胺核和疏水的十六烷基臂,可在氯仿等溶剂中形成单分子胶束。以此单分子胶束为纳米反应器封装Cd2+,进一步与S2-反应后得到尺寸均一的CdS量子点。同时,我们也成功地将该方法拓展到制备直径小于2 nm的Au、Ag等金属纳米晶体。3.超分子自组装纳米反应器制备CdS量子点及其相行为研究提出了一种利用超分子自组装纳米反应器制备CdS量子点的新策略。自组装纳米反应器是由棕榈酸和端基为胺基的超支化聚合物通过静电相互作用和离子对构筑的。在水油两相体系中,水相的Cd2+首先自发转移至位于氯仿相的自组装纳米反应器中,在与水相的S2-反应后,即可生成浅黄色的CdS量子点氯仿溶液。通过加入三乙胺,自组装纳米反应器中制备的CdS量子点将从氯仿相转移至水相。经过透析和旋转蒸发干燥,CdS量子点再次溶于含有棕榈酸的氯仿溶液中,从而实现了CdS量子点在水油两相之间的相互转移。4.利用超支化聚合物原位制备磁性非病毒基因载体及磁转染性能研究实现了一种原位制备有机-无机纳米杂化磁性非病毒基因载体的新路线。有机-无机纳米杂化磁性非病毒基因载体是在二价铁盐和不同分子量的超支化聚乙烯亚胺(HPEI)存在下制备的。HPEI是最理想的非病毒基因载体之一,在本文中它不仅用作纳米反应器和稳定剂来合成磁性纳米晶体,而且被我们巧妙地用来代替碱金属氢氧化物和氨水为反应提供所需要的碱。通过调节HPEI/FeSO4·7H2O(w/w)和改变HPEI的分子量,制备了不同磁含量和饱和磁化强度的磁性非病毒基因载体。MTT评估表明这种磁性非病毒基因载体的毒性比相对应的HPEI的毒性小。我们进一步研究了这种磁性非病毒基因载体的磁转染性能,研究发现荧光素酶在COS-7细胞内的表达量最高可达到HPEI标准转染的13倍。5.利用两亲性超支化聚合物实现无机纳米晶体在水油两相界面的组装建立了一种利用两亲性核壳型超支化聚合物实现CdTe和Au纳米晶体在水/油界面组装的新途径。以CdTe纳米晶体为例,CdTe纳米晶体首先被转移至含有十六烷基酰氯封端超支化聚酰胺胺(HPAMAM-PC)的氯仿溶液中,通过降低水相的pH值或在水相引入α-环糊精(α-CD),CdTe纳米晶体便在水/氯仿界面进行自组装。我们对得到的CdTe/HPAMAM-PC自组装膜进行了荧光显微镜、UV-Vis、PL、TEM、EDS、FT-IR、DSC和TGA等表征。综上所述,本论文基于超支化聚酰胺胺化学改性或非共价相互作用构筑了不同类型的纳米反应器并用于合成CdS量子点和Au等纳米晶体;利用超支化聚乙烯亚胺原位制备了封装磁性纳米晶体的有机-无机纳米杂化非病毒基因载体,并考察了磁转染性能;我们还利用两亲性的超支化聚酰胺胺分别封装CdTe和Au纳米晶体,并分别实现了CdTe和Au纳米晶体在水/氯仿界面的自组装。总之,我们制备了一系列无机纳米晶体/超支化聚合物纳米杂化材料,为超支化聚合物和纳米晶体的实际应用提供了重要信息。更多还原

【Abstract】 Hyperbranched polymers are a kind of highly branched polymers with three-dimension topological structures. They have many inner cavities and a large amount of terminal functional groups. Due to their unique molecular structures and facile synthsis route, hyperbranched polymers have received much attention and remarkable development has been made on their synthesis, characterization and modification in the passed decades. This leads to an increasing interest on the application of hyperbranched polymers, such as the molecular self-assembly, the control-release of medicine, nanoparticle encapsulation, gene transfection, and so on. Howerver, there are still a lot of areas to be explored and improved. In this dissertation, some new researches on the application of hyperbranched polymers have been made: (1) We synthesized hyperbranched poly(amidoamine) (HPAMAM) via the AB+Cn strategy and prepared various nanoreactors based on chemical modification or non-covalent interactions to synthesize CdS quantum dots (QDs) and Au, Ag metal nanocrystals (NCs); (2) Hyperbranched poly(ethylenimine) (HPEI) was used to in situ prepare magnetic nonviral gene vectors and the magnetization properties was also investigated; (3) The CdTe and Au NCs encapsulation by amphiphlic HPAMAM and the self-assembly of CdTe and Au NCs at the water/chloroform interface were realized, respectively. The details and main conclusions are described as follows:1. Preparation of Nanocrystals within Hyperbranched Polymer NanoreactorsHyperbranched poly(amidoamine) (HPAMAM) with ester groups was synthesized and used as nanoreactors to prepare CdS quantum dots (QDs) with small particle size and low size-distribution. The effects of molar ratio of Cd2+/S2-, reaction temperature, pH value in the reactions and aging time on the photoluminescence of CdS QDs were investigated. The resulting CdS/HPAMAM nanocomposites were then characterized by UV-Vis, PL, TEM and FT-IR. 2. A New Two-phase Route to Nanocrystals Using Amphiphilic Hyperbranched Polymers as Unimolecular NanoreactorsA new two-phase route has been developed to prepare monodisperse CdS QDs. In a two-phase system, chloroform and water were used as separate solvents for palmitoyl chloride functionalized hyperbranched poly(amidoamine) (HPAMAM-PC) and cadmium acetate/sodium sulfide, respectively. The amphiphilic HPAMAM-PC with a hydrophilic dendritic core and hydrophobic arms formed stable unimolecular micelles in chloroform and was used to encapsulate aqueous Cd2+ ions. After reaction with S2- ions from aqueous phase, monodisperse CdS QDs stabilized by HPAMAM-PC unimolecular micelles were obtained. Au and Ag nanocrystals smaller than 2 nm were also prepared by this method.3. Preparation of Nanocrystals within Supramolecular Self-assembly Nanoreactors and their Phase Transfer BehaviorA new strategy for the synthesis of CdS QDs within supramolecular self-assembly nanoreactors has been described. The self-assembled nanoreactors were readily constructed through the electrostatic interactions and ion pairs between palmitic acid and the terminal amine groups of hyperbranched polymer. In a chloroform/water two-phase system, aqueous Cd2+ ions were spontaneously encapsulated into the cavities of self-assembly nanoreactors in chloroform. After reaction with S2- ions, the CdS QDs with high stability were obtained. By the addition of excess triethylamine, CdS QDs formed in the self-assembly nanoreactors were transferred from organic phase into aqueous phase. After dialysis and rotorary evaporation, aqueous CdS QDs could be redispersed into chloroform solution containing palmitic acid.4. In situ Preparation of Magnetic Nonviral Gene Vectors and Magnetofection in VitroA new route to in situ preparing magnetic nonviral gene vectors in the form of organic/inorganic hybrids was realized. The magnetic nonviral gene vectors were prepared in the presence of ferrous salts and HPEI with different molecular weights. HPEI, one of the most promising nonviral vectors, was not only utilized as the nanoreactors and stabilizers to prepare magnetic nanoparticles, but also skillfully used as a base supplier to avoid introducing alkali hydroxide or ammonia. Magnetic nonviral gene vectors with various magnetite contents and saturation magnetizations were gained by changing the weight ratio of HPEI to FeSO4·7H2O and the molecular weight of HPEI. MTT assays suggested that the resulting magnetite/HPEI gene vectors had lower cytotoxicity compared with pure HPEI. The magnetite/HPEI nonviral gene vectors were used for magnetofection. It was found that the luciferase expression level mediated by magnetite/HPEI in COS-7 cells under a magnetic gradient field was approximately 13-fold greater than that of standard HPEI transfection in the best case.5. Self-assembly of Nanocrystals at the water/oil Interface by Amphiphilic Hyperbranched PolymersA general strategy for realizing the self-assembly of aqueous CdTe and Au NCs at the water/oil interface by means of amphiphilic core-shell hyperbranched polymer has been proposed. In the case of CdTe NCs, for example, aqueous CdTe NCs were firstly transferred into chloroform phase in the presence of palmityl choloride functionalized hyperbranched poly(amidoamine) (HPAMAM-PC), and then self-assembled at the water/chloroform interface by decreasing the pH value of aqueous phase or introducingα-cyclodextrins (α-CDs) to the aqueous phase. The resulting CdTe/HPAMAM-PC self-assembly film was characterized by fluorescence microscopy, UV-Vis, PL, TEM, EDS, FT-IR, DSC and TGA.In conclusion, based on hyperbranched polymers, different kinds of nanoreactors were prepared by chemical modification or non-covalent interactions and used to synthesize CdS QDs, Au and Ag NCs. Magnetic NCs were in-situ prepared within HPEI nonviral gene vetors and their magetofection properties were investigated. The self-assembly of CdTe and Au NCs was also realized by amphiphilic hyperbranched polymers. These NCs/hyperbranched polymer hybrid materials may provide important informations to the applications of hyperbranched polymers and NCs.更多还原