【作者】 金桥；

【导师】 沈家骢； 计剑；

【作者基本信息】 浙江大学 ， 材料学， 2010， 博士

【摘要】 纳米微载体由于在催化化学、材料制备、生物医药等多方面有着极为重要而广泛的应用价值,长期以来一直是科研领域研究的热点。本论文将有机功能分子的光化学转变应用到环境敏感全亲水性嵌段聚合物的超分子组装研究中,通过研究有机光化学转变对两亲聚合物组装和解组装行为的影响规律,探索具有光控功能的新型智能微载体的构筑。研究围绕光响应的亲疏水转变、可逆光交联和光响应的主客体相互作用,分别开展了以下工作：1、将螺吡喃的光学异构转化引入到多重胶束化体系中,来构筑多重环境响应的胶束体系,实现了光响应胶束的核和壳的相互转化。首先利用连续的原子转移自由基聚合(ATRP)合成了结构明确且窄分布的嵌段聚合物聚甲基丙烯酸螺吡喃酯-b-甲基丙烯酸二乙二醇酯(PSPMA-b-PDEGMMA).紫外可见光谱(UV-vis)、透射电镜(TEM)、粒度分析仪等表征手段证实了该嵌段聚合物在15℃可见光照射下会形成PSPMA为核的胶束,在30℃紫外光照射下会形成PDEGMMA为核的胶束。研究进一步采用香豆素102为模型药物,将PSPMA-b-PDEGMMA聚合物胶束作为智能纳米微载体,实现了光响应和热响应的疏水荧光染料的可控释放与再封装。2、将能可逆光交联的香豆素基团引入到环境敏感多重胶束化体系中,来构筑多重环境响应的胶束和纳米凝胶体系。研究首先利用ATRP合成了能可逆光交联的全亲水性嵌段共聚物聚丁二醇酸甲基丙烯酸酯-b-(甲基丙烯酸二乙二醇酯-co-甲基丙烯酸羟甲香豆素酯)(PSPMA-b-P(DEGMMA-co-CMA)).并采用激光光散射、ζ电位、透射电镜(TEM)、水相核磁证实了其基于温度和pH值敏感的"schizophrenic"胶束化转变行为：在20℃pH为3的时候,形成了PSPMA为核的胶束,而在35℃pH为10的时候,形成了PDEGMMA为核的胶束。研究进一步将胶束用紫外光进行照射,实现了胶束结构的固定,得到光可逆控制的核交联的胶束和壳交联的胶束。并最终通过调节溶液温度和pH值使交联胶束的核由疏水变成亲水,将交联胶束转化为纳米凝胶,通过对照射紫外光的波长、强度和照射时间的控制实现了纳米凝胶的交联度和溶胀度的有效调控。研究进一步探索了采用光交联纳米凝胶为模板进行金纳米粒子原位合成的规律。采用pH值响应的可逆光交联的嵌段聚合物聚氧乙烯-b-(甲基丙烯酸二甲胺基乙酯-co-甲基丙烯酸羟甲香豆素酯)(PEO-b-P(DEA-co-CMA)),通过紫外光照射和溶液pH值的调节,获得了pH响应的可逆光交联的纳米凝胶。通过质子化带正电荷的纳米凝胶原位负载AuCl4-离子,原位合成了粒径小于5nm的金纳米粒子。紫外可见光谱显示原位合成的金纳米粒子可成功催化还原对硝基苯酚,并具有很高的催化活性。3、将光响应的偶氮苯与环糊精的主客体作用与嵌段聚合物的溶液组装相结合,探索通过光响应调控纳米组装体的形貌变化。研究首先通过ATRP合成了一系列含偶氮苯的嵌段聚合物聚氧乙烯-b-(甲基丙烯酸(6-偶氮苯基)已二醇酯-co-甲基丙烯酸二甲胺基乙酯)(PEO-b-P(AzoMA-co-DMAEMA))。激光光散射和透射电镜表明,PEO-b-P(AzoMA-co-DMAEMA)能在水中形成囊泡结构,囊泡的尺寸和形状可以通过AzoMA和DMAEMA的比例进行调节。向溶液中加入p-环糊精,可通过p-环糊精和反式偶氮苯的包结络合作用调节组装体的亲疏水性,获得由囊泡到胶束,最后无法形成规则的组装体的多重转变。进一步基于偶氮苯在紫外光—可见光下由顺式到反式的可逆转变,可通过偶氮苯与环糊精的可逆组装与解组装,实现光可控的囊泡的组装与解组装。更多还原

【Abstract】 Nanocarriers have attracted much interest in recent years due to their promising applications in diverse fields such as catalysis, material preparation and biomedicine. In this dissertation, a series of photo-responsive block copolymer nanocarriers were fabricated via different non-covalent interactions with diverse chemical architectures. This dissertation focuses on the pohoto controllable self-assembly and disassembly of double hydrophilic block copolymers (DHBCs). The details are given in the following parts:1. A novel photo and thermo double responsive block copolymer was developed to fabricate micelles and reverse micelles in aqueous solution. The block copolymer was synthesized by ATRP block copolymerization of a spiropyran-containing methacrylate (SPMA) with di(ethylene glycol) methyl ether methacrylate (DEGMMA). By facile control of the photo irradiation and solution temperature, PSPMA-core and PDEGMMA-core micelles can be obtained respectively. The thermo and photo-responsive micelles were used as smart polymeric nanocarriers for controlled encapsulation, triggered release and re-encapsulation of model drug coumarin 102. The double responsive self-assembly and disassembly were tracked by dynamic light scattering (DLS), transmission electron microscopy (TEM) and fluorescence spectroscopy.2. Photo cross-linkable double hydrophilic block copolymer poly(butanedioic acid,1-[3-[(2-methyl-1-oxo-2-propen-1-yl)oxy]propyl] ester)-b-poly(methoxydi (ethylene glycol)methacrylate-co-4-methyl-[7-(methacryloyl)oxyethyloxy] coumarin) (PSPMA-b-P(DEGMMA-co-CMA)) was synthesized via atom transfer radical polymerization (ATRP). The temperature and pH responsive "schizophrenic" micellization behaviors of PSPMA-b-P(DEGMMA-co-CMA)) were investigated to obtain P(DEGMMA-co-CMA)-core and PSPMA-core micelles. After the two types of micelles were exposed to 365 nm UV light, core cross-linked (CCL) micelles and shell cross-linked (SCL) micelles were facilely prepared. The photo cross-linking was proved to be reversibly controlled under alternative irradiation of 365 nm and 254 nm UV light. More interestingly, block copolymer nanogels were fabricated by translating the hydrophobic core of the CCL and SCL micelles into hydrophilic via adjusting the temperature and pH. The sizes, swollen degrees and cross-linking degrees of the block copolymer nanogels can be facilely controlled by UV light irradiation.We also designed reversibly photo cross-linkable pH-responsive block copolymer poly(ethylene oxide))-b-poly(2-(diethylamino)ethyl methacrylate-co-4-methyl-[7-(methacryloyl) oxyethyloxy] coumarin) (PEO-b-P(DEA-co-CMA)). This block copolymer can be used to construct photo cross-linkable pH-responsive nanogels. The nanogels can be served as nanoreactors for the synthesis of gold nanoparticles. The protonated DEA units were first coordinated with HAuC14, and then the electrostatically bounded AuC14-anions were reduced to gold nanoparticles by NaBH4. The catalytic activity of the nanogel-supported gold nanoparticles was further studied.3. Because of the suparmolecular host-guest interactions between photo-responsive trans-azobenzene andβ-cyclodextrin (β-CD), the reversible photo-responsive supramolecular self-assembly and disassembly of vesicles were constructed. Azobenzene-containing block copolymer poly(ethylene oxide)-b-poly (6-[4-phenylazo phenoxy]hexyl methacrylate-co-2-(dimethylamino)ethyl methacrylate) (PEO-b-P(AzoMA-co-DMAEMA)) was successfully designed to explore the self-assembly behavior in aqueous solution. PEO-b-P(AzoMA-co-DMAEMA) can self-assemble into vesicles. The morphologies and sizes of the vesicles can be controlled by copolymerization of hydrophobic AzoMA with different content of DMAEMA. Spherical vesicle-to-compound vesicle-to-irregular vesicle transitions were observed just by facilely adjusting the content of DMAEMA and AzoMA. After the addition of different content ofβ-CD, vesicles were transited to micelles and at last dissociated. Alternating irradiation of the solution with UV and visible light induced the reversible supramolecular self-assembly and disassembly of vesicles because of the photo-induced trans-to-cis isomerization of azobenzene units. The supramolecular self-assembly and disassembly procedure was studied by dynamic light scattering (DLS), transmission electron microscopy (TEM) and UV-vis spectra.更多还原