以半胱氨酸为连接子的新型两亲性嵌段共聚物的合成及其与纳米粒子的自组装研究

发布时间：2018-10-17 10:40

【摘要】：具有不对称结构的两亲性嵌段共聚物,可以在选择性溶剂中自组装形成各种不同形貌的聚集体,包括球形胶束、棒状胶束、双连续结构以及囊泡等。近年来,纳米粒子与嵌段共聚物组装形成的各种结构的杂化聚集体逐渐成为人们的研究热点,这些杂化聚集体不但综合了嵌段共聚物和纳米粒子的固有性质,而且呈现出了更为复杂的结构和功能,在生物医药、光电子学、催化等领域有着广阔的应用前景。精确控制纳米粒子在不同形貌的聚集体中的定位和分布将影响该杂化聚集体的性质及其潜在的应用,因而具有非常重要的研究意义。囊泡是迄今为止研究最为广泛的一类自组装体,已经有大量文献报道了将各种纳米粒子掺入到囊泡结构中,然而将纳米粒子精确地封装到囊泡的亲/疏水界面仍然是一项具有挑战性的工作。目前,控制纳米粒子定位于囊泡的亲/疏水界面的方法主要是利用两亲性三嵌段共聚物来构建自组装体,其中,两条外侧链段分别形成囊泡壁和亲水壳,中间链段则用来和纳米粒子相互作用并将其束缚在囊泡壁的内外交界面上。本文设计了一种以半胱氨酸为连接子的新型两亲性二嵌段共聚物,利用链中间的巯基官能团分别对两类纳米粒子进行聚合物表面修饰,并研究简单线性二嵌段共聚物及其相应的接枝纳米粒子在溶液中的自组装行为。此外,对掺有硫化铜纳米粒子(CuSNPs)的杂化囊泡聚集体进行近红外光刺激-响应实验,研究其近红外光响应特性,进一步探索其实际应用价值。具体的研究内容分为以下三个部分:1.设计并利用原子转移自由基聚合(ATRP)的方法制备了一系列具有不同疏水链段长度,链中间含有巯基官能团的两亲性二嵌段共聚物PEG114-b-SH-PSn,通过1HNMR和GPC表征分析,确定了制备的嵌段功能大分子的数均分子量和两亲性嵌段比。2.通过配体交换的方法,利用制备的两亲性嵌段功能大分子PEG-b-SH-PS替换小分子稳定剂,分别对金纳米粒子(GNPs)和硫化铜纳米粒子(CuS NPs)进行表面修饰,得到了两类新颖的嵌段共聚物接枝纳米粒子。通过对聚合物修饰前后的纳米粒子进行一系列的表征分析可知,嵌段共聚物成功地接枝到了纳米粒子的表面,并通过热重分析(TGA)结果计算出了纳米粒子表面聚合物的接枝率。3.通过透射电镜(TEM)对两亲性嵌段共聚物和纳米粒子组装形成的杂化囊泡结构进行观察后发现,纳米粒子基本分布在囊泡壁的内外界面上。对掺有CuS NPs的聚合物囊泡的水溶液进行近红外光刺激-响应实验,发现囊泡在980 nm的近红外光照射后,由于光热效应导致体系温度升高,囊泡的中空球形结构被破坏,从而证实该纳米复合材料具有很好的近红外光响应特性,在分子成像、光热治疗等领域有着潜在的应用前景。
[Abstract]:Amphiphilic block copolymers with asymmetric structures can self-assemble in selective solvents to form aggregates of various morphologies, including spherical micelles, rod-like micelles, double-continuous structures and vesicles. In recent years, hybrid aggregates with various structures formed by the assembly of nano-particles and block copolymers have gradually become the focus of research. These hybrid aggregates not only integrate the inherent properties of block copolymers and nanoparticles, Moreover, it presents more complex structure and functions, and has a broad application prospect in biomedicine, optoelectronics, catalysis and other fields. Precisely controlling the location and distribution of nanoparticles in aggregates with different morphologies will affect the properties and potential applications of the hybrid aggregates, so it is of great significance to study the hybrid aggregates. Vesicles are one of the most widely studied self-assembled materials. There have been a lot of literatures about the incorporation of various nanoparticles into the vesicle structure. However, it is still a challenging task to accurately encapsulate nanoparticles into the lipophilic / hydrophobic interface of the vesicles. At present, the main method to control the localization of nanoparticles at the lipophilic / hydrophobic interface of vesicles is to construct self-assembly by using amphiphilic triblock copolymers, in which two outer segments form vesicles and hydrophilic shells, respectively. The intermediate segment is used to interact with nanoparticles and bind them to the inner and outer interface of the vesicle wall. In this paper, a novel amphiphilic diblock copolymer with cysteine as linker was designed. The polymer surface was modified by mercapto functional groups in the middle of the chain. The self-assembly behavior of simple linear diblock copolymers and their corresponding grafted nanoparticles in solution was studied. In addition, the hybrid vesicle aggregates doped with copper sulfide (CuSNPs) nanoparticles were stimulated by near-infrared light (NIR). The characteristics of NIR response were studied, and the practical application value was explored. The specific research content is divided into the following three parts: 1. A series of amphiphilic diblock copolymers (PEG114-b-SH-PSn,) with different hydrophobic segment lengths and mercapto functional groups in the chain were prepared by atom transfer radical polymerization (ATRP) and characterized by 1HNMR and GPC. The number average molecular weight and amphiphilic block ratio of the prepared block functional macromolecules were determined. 2. 2. By ligand exchange, the gold nanoparticles (GNPs) and copper sulfide nanoparticles (CuS NPs) were modified by using amphiphilic block functional macromolecule PEG-b-SH-PS instead of small molecular stabilizers, respectively. Two novel block copolymer grafted nanoparticles were obtained. Through a series of characterization and analysis of polymer nanoparticles before and after modification, it was found that block copolymers were successfully grafted onto the surface of nanoparticles, and the grafting rate of polymers on nanoparticles was calculated by thermogravimetric analysis (TGA). The structure of hybrid vesicles formed by amphiphilic block copolymers and nanoparticles was observed by transmission electron microscopy (TEM). The near-infrared photostimulation-response experiments of aqueous solution of polymer vesicles doped with CuS NPs were carried out. It was found that the hollow spherical structure of the vesicles was destroyed due to the photothermal effect when the vesicles were irradiated with 980 nm near-infrared light, and the temperature of the vesicles was increased due to the photothermal effect. It is proved that the nanocomposites have good near-infrared response and have potential applications in molecular imaging, photothermal therapy and so on.
【学位授予单位】：东南大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：O631.1

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