【作者】 刘丽；

【导师】 刘凤岐；

【作者基本信息】 吉林大学 ， 高分子化学与物理， 2009， 博士

【摘要】 分子内同时含有亲水单元和疏水单元的聚合物称为两亲性聚合物。由于聚合物中两亲性链段彼此互不相容,容易发生微相分离,使其在选择性溶剂、表面和本体结构中呈现出独特的性质。因此,两亲性聚合物成为化学、医学及生命科学等领域广泛研究的对象。合成两亲性聚合物的方法主要有活性聚合和化学改性两种。活性聚合可以合成各种确定结构的两亲性聚合物,但是反应条件较苛刻。因此,本文工作主要是采用化学改性的方法使丙烯酸酯类聚合物亲水化得到两亲性的丙烯酸酯类聚合物,并对它们的性质和应用进行了讨论。第一种为带有大量羧酸根离子的两亲无规共聚物,其作为高分子表面活性剂应用于苯乙烯的乳液聚合中具有较好的乳液稳定性。第二种为聚乙二醇单甲醚(mPEG)接枝的两亲聚合物,它具有pH敏感、温度敏感及无机盐敏感等性质。第三种为聚乙二醇(PEG)交联并经过mPEG接枝的两亲性聚合物网络(凝胶),这种凝胶在环境pH值、温度和离子强度等条件的刺激下发生明显的体积相转变,即其溶胀度发生突变。更多还原

【Abstract】 In recent years, there has been increasing interest in the synthesis and properties of the amphiphilic polymer due to this phase transition lied in the balance of hydrophilic and hydrophobic interactions in the system. So some unique properties are present. The primary focus includes nanometer materials （L-B films）, side-chain polymer liquid crystal, biomaterials, drug carriers, polymer alloy, flocculant, adhensive, polymeric emulsifer and so on. The amphiphilic polymer has become the research object of chemistry, medicine, physics and life science.According its chemical structure, the amphiphilic polymer includes four kinds of block, graft, random and polymer network. Its synthetic method mainly included the living polymerization and the chemical modified. The advantage of the former was regular structure of products, but reaction condition relatively harsh. Compared with the former, the latter was simple and was applied to the synthesis of the polymeric surfactants.The polymeric surfactant is similar to small-molecule surfactants, both are composed of hydrophilic and hydrophobic. However, the surface activity of them has larger difference such as the surface tension reduction and so on. Even so, polymeric surfactant can stabilize the colloid particles owing to steric stabilization and is used as stabilizer. In this paper, an amphiphilic random polymer was synthesized by the chemical modified. The emulsion polymerization kinetics of styrene stabilized by this copolymer was investigated. The influence factors, including polymeric surfactant concentration, initiator concentration and polymerization temperature, were systematically studied. The results showed that the polymeric surfactant has good stability to emulsion. The rate of polymerization increased with the surfactant concentration, initiator concentration and reaction temperature. The nucleation model is related to the polymeric surfactant concentration. At the higher [S], droplets nucleation and micelle nucleation coexisted in the polymerization system; at the lower [S], only the droplets nucleation process existed. It would be speculated that a kind of large heterogeneous particles with multiple-active-sites was formed in the polymerization system. The influence of initiator concentration was complex. It was attributed to the barrier effect of the polymeric surfactant around the monomer droplets.The methoxy polyethylene glycol （mPEG） is a kind of polyethylene glycol terminated by methyl and composes of quantitative ethoxyl. Owing to the hydrogen bond interaction between oxygen atom and H₂O, mPEG has a good hydrophilic. So, it was used as the hydrophilic of the amphiphilic polymer, and because of its biocompatibility, it was applied as polymeric drug carrier. P （MMA-co-MAh）-g-mPEG was synthesized by grafting onto method. The grafting ratio of polymers was confirmed by ¹HNMR. The environment sensitivity of polymers was discussed such as pH、temperature and inorganic salt etc. The results showed that the degree of dissociation of carboxyl influenced the phase transition. When the degree of dissociation was higher, the polymer-water interaction increased and the hydrophilic of polymer increased. The other way round, PEG ether units form intra/intermolecular hydrogen bonds with the acid groups, the polymer-polymer interaction increased and the phase transition happened. When the degree of dissociation was lower, the increasing of temperature can destruct hydrogen bond between polymer and water, phase separation emerged, it made the grafted polymer sensitivity. Except pH and temperature, salt, alcohol and urea can affect the phase separation of polymer. For example, salting-out effect can decrease polymer’s LCST. Alcohol can disrupt the hydrophobic interactions in the aqueous polymer solution. Urea is known as a hydrogen-bond breaker. Both made polymer’s LCST increasing.The amphiphilic polymer network is a typical intelligent polymer materials. Because its structure include hydrophilic and hydrophobic, the interaction between two segments can happen reversible change. So the polymer network has obvious the volume phase transformation. In this paper, the amphiphilic polymer network was prepared by thermal cross-linking and its sensitivity was discussed. The results showed that the swelling rate increased with the increasing of the content of crosslinking agent and pH. The swelling rate of polymer network is relative to the dissolve degree of carboxyl. The dissolve degree of carboxyl increased with pH and the interaction increase between carboxyl and water, the curl molecular chain changed extension, water more easily to enter internal. Through the discussion of swelling kinetics, the deswelling emerges at lower pH, this attributed to the effect of physical crossing.In summary, Radical polymerization and chemical modified were used to sysnthenics liner and network amphiphilic polymer. One of products is polymeric emusifer and applied to emulsion polymerization as stabilizer. The other two possessed environment sensitivity such as pH, temperature and ionic strength and so on. These properties were discussed in this paper.更多还原