【作者】 陈振；

【导师】 和亚宁；

【作者基本信息】 清华大学 ， 材料科学与工程， 2011， 硕士

【摘要】 二芳基乙烯的双亲性嵌段共聚物可同时具有光响应及自组装性能，在光信息存储、光学开关、光传感器以及光控缓释等领域具有潜在的应用价值。本论文主要内容包括双亲性二芳基乙烯嵌段共聚物的合成、结构性能的表征以及研究共聚物在水溶液中的自组装行为和光响应性。论文的主要工作和研究成果如下：利用可逆的加成-断裂链转移自由基聚合（RAFT），以聚乙二醇（PEG）作为大分子链转移剂合成了一系列双亲性二芳基乙烯嵌段共聚物PEGx-b-PSDTEy。采用凝胶渗透色谱、核磁共振、示差扫描量热计、紫外可见光谱以及荧光光谱等手段对制备的嵌段共聚物作了系统分析和表征。氢核磁谱图结果证实当共聚物分别受到紫外光和可见光照射后，侧链中的二芳基乙烯可以进行转化率接近100%的光致异构反应（闭环和开环反应），共聚物链段的长短对二芳基乙烯的光响应性有很大影响。荧光光谱结果表明嵌段共聚物中的二芳基乙烯可以有效地调控罗丹明B的荧光强度，实现可逆的光控荧光淬灭和发射。PEGx-b-PSDTEy在选择性溶剂中，可以自组装形成结构规整的聚集体结构，包括空心囊泡和实心胶体球等。利用激光光散射、透射电镜等表征了聚集体的尺寸和形貌。结果表明，自组装胶体球的尺寸和内部结构跟亲水和疏水链段的比例和自组装的条件有关。PEG43-b-PSDTE29的两种光异构体表现出差异明显的自组装行为。无色的PEG43-b-PSDTE29open可以在水中自组装形成空心囊泡聚集体。在相同条件下，蓝色的PEG43-b-PSDTE29close只能形成实心胶体球。同时，空心囊泡聚集体受到紫外光辐射后，会发生光致破裂。实心胶体球受到可见光照射后，形貌没有发生明显变化。更多还原

【Abstract】 Amphiphilic block copolymers containing photoresponsive dithienylethenegroups have self-assembly and photoresponsive properties, which can be potentiallyapplied in many fields such as optical information storage, optical switches, opticalsensors and light-controlled release, etc. This dissertation includes synthesis ofamphiphilic dithienylethene diblock copolymers, characterization of their structuresand properties, study of their self-assembly and photoresponsive properties. The mainachievements of this thesis are summarized as follows.A series of amphiphilic diblock copolymers (PEGx-b-PSDTEy) containingphotochromic dithienylethene (DTE) pendants had been synthesized by reversibleaddition fragmentation chain transfer (RAFT) radical polymerization with PEG asmacro-chain transfer agent. The molecular weight, structures and properties of thesediblock copolymers were carefully characterized by GPC, NMR, UV–vis and DSCmeasurements. The analyses results indicated that the diblock copolymers possessedwell-defined structures and narrow molecular weight distributions. The1H NMRanalyses verified that nearly100%percent of the DTE pendants in the diblockcopolymers were underwent photochemical ring-closing and-opening reactions whenirradiated with UV and visible light respectively. The chain length of diblockcopolymers had a great influence on the photoresponsive properties ofdithienylethene pendants. Fluorescence spectra results indicated that DTE pendants inthe diblock copolymers could effectively control the fluorescence intensity ofRhodamin B and realize the reversible photo-modulated fluorescence quench andemission.Amphiphilic dithienylethene diblock copolymer (PEGx-b-PSDTEy) canself-assemble to hollow vesicle-like structures or colloidal spheres with solid interiorsprepared by gradually adding deionized water to their THF solutions. The proportionbetween hydrophilic and hydrophobic blocks and the self-assembly condition showedeffect to the size and internal structure of the colloidal spheres self-assemblies, which were characterized by using laser light scattering (LLS) and TEM methods. The twooptical isomers of the PEG43-b-PSDTE29showed entirely different self-assemblybehaviors. Hollow vesicle-like structures were formed by gradually adding deionizedwater to the colorless PEG43-b-PSDTE29open(DTE in open form) THF solution. Underthe same condition, the aggregates formed in the blue PEG43-b-PSDTE29close(DTE inclosed form) solution were the colloidal spheres with solid interiors. Theisomerization of DTE pendants could cause the deformation of the vesicle-likestructures but unchanged morphology of colloidal spheres. Above result demonstratesa kind of novel photo-modulated self-assembly behavior and morphology of theaggregates of amphiphilic diblock copolymer.更多还原