【作者】 刘宏伟；

【导师】 仲崇立；

【作者基本信息】 北京化工大学 ， 化学工程， 2007， 博士

【摘要】 近年来，随着聚合材料和现代医学的高速发展，药物控释与靶向定位技术逐渐成为材料和药学领域的研究热点。聚合物药物控释系统就是利用天然或合成的聚合物作为药物的载体或介质，制成一定的剂型，控制药物在人体内的释放度，使药物按设计的剂量、在要求的时间范围内把药物运到特定的病理部位后以一定的速度在人体内缓慢释放，以达到高效和定向治疗的目的。本工作主要进行以下几个方面的研究：高分子材料在水溶液中最低临界溶解温度的研究、聚乙烯晶体表面接枝聚环氧乙烷、表面活性剂在微胶束表面吸附性质的模型化研究。主要成果为：1．利用分子连接性指数分别建立了估算聚苯乙烯等8种聚合物在不同种有机溶剂中的低临界溶解温度的模型，及适用于任何聚合物的通用模型。对于某种特定聚合物的模型，其预测误差在3％以内，而通用模型，其预测误差一般也在10％以内。对于特定聚合物的低临界溶解温度的预测模型，只需知道溶剂的分子的分子连接性指数，对通用模型，则也只需加入聚合物分子的分子连接性指数，计算方便适用，同时拓宽了分子连接性指数的应用。2．采用全原子动力学模拟方法，结合先进的COMPASS(Condensed-phase Optimized Molecular Potential for AtomisticSimulation Studies)力场，对聚乙烯(Polyethylene，PE)晶体表面接枝聚环氧乙烷(Poly(ethylene oxide)，PEO)的接枝层表面形态及接枝层对PE表面润湿性的改善进行了研究。研究表明，随着接枝长度及接枝密度的增加，表面接枝的形态由“蘑菇”形逐步变化为“重叠的蘑菇”形，最后变为“刷子”形。PEO的接枝密度对PE表面润湿性的改善有较大影响，接枝根数为8和16根时，对PE表面的润湿性有较大改善；当接枝根数为24和32时，对PE表面的影响最小；但接枝密度达到一定大小如48以上后，对改善表面润湿性效果又变得明显起来。而就长度而言，憎水表面接枝亲水性高分子时接枝长度在一定范围内，即接枝单体数为10-15时，其润湿效果最好。3．采用耗散粒子动力学(Dissipative Particle Dynamics，DPD)模拟方法，研究了表面活性剂在接枝型两亲性共聚物形成的微胶束表面的吸附情况。本文主要对亲水性聚合物的接枝密度和长度对表面活性剂吸附的影响进行了研究。结果表明，接枝亲水性聚合物能有效的阻止表面活性剂在微胶束表面的吸附，当接枝长度不变时，接枝根数在2-5根枝时既能有效的阻止表面活性剂的吸附，又能保持微胶束的形状，此时，亲水部分与憎水部分的体积比在0.1667-0.4167之间；当接枝密度固定时，接枝长度大于4个beads时就能有效的阻止表面活性剂的吸附。当亲水枝的长度在4-6个beads，即体积分率在0.1667-0.25时，微胶束表面能最为有效的摆脱表面活性剂的吸附和包围，即此时，表面活性剂在微胶束表面的吸附不仅吸附最少，而且不改变微胶束的形状。4．采用耗散粒子动力学模拟方法，研究了水溶液中的微胶束在接枝前后，存在剪切外场的情况下，其形貌及流变性质。微胶束在接枝前，被表面活性剂吸附甚至形成包围。且在剪切作用下也较为稳定，难以在药物运输和靶向定位中起到作用。而接枝后的微胶束不仅能摆脱表面活性剂的吸附甚至包围，同时由于其在不同的剪切外场的作用下变得不稳定，因此选取相应的剪切流下的稳定结构或者根据不同的剪切流来达到运输和靶向定位的目的。从而从分子水平上说明了两亲性微胶束与表面活性剂在水溶液中复杂的流变性质，为药物的控释制剂的制备提供了有用的信息。更多还原

【Abstract】 With the development of polymers and modern medicine science, drug controlled release and targeting technologies have received much attention. Polymer drug controlled release systems are drug carriers based on natural or synthetic polymers that can control drug release and targeting. With the fast development of science and technology, smart drug controlled release systems are receiving more and more attention, which can improve the therapeutic efficiency as well as to reduce negative effects. As a result, it is very important to study technologies that can improve the controlled release of drugs. In this work, correlations for the estimation of theθ(lower critical solution temperature, LCST) for polymer solutions were developed, and morphology and wettability of polyethylene surface grafting poly(ethylene oxide) as well as surfactant adsorption on the surface of polymeric micelles in aqueous solution were investigated. The main results obtained are:1．Correlations for the estimation of theθ(lower critical solution temperature, LCST) for Polystyrene, Polyethylene, Polypropylene, Polybutene-1, Polyisobutylene, Polypentene-1, Poly(4-methylpentene-1) and Polydimethylsiloxane solutions were proposed based on the molecular connectivity index. And a general model ofθ(LCST) for polymer solutions was also proposed based on the molecular connectivity index. The correlations give satisfactory estimation of theθ(LCST), with the overall average errors smaller than 3 % and 10 % for the two kinds of models, respectively. Since only connectivity indices were used in the newly proposed correlations, they are general models with better predictive capability.2．Morphology of grafting poly(ethylene oxide) chain and wettability of polyethylene surface were investigated when poly(ethylene oxide) was grafted to polyethylene surface using molecular dynamics simulation with the COMPASS (Condensed-phase Optimized Molecular Potential for Atomistic Simulation Studies) force field. With the increase of the density of the graft chain, morphology of graft chain showed the "mushroom", the "overlapping mushroom" or "brush" respectively. The density of the graft chain had great effects on the wettibillity of the PE. When the number of the graft chain was 8 and 16, the PE surface had better wettability than the pristine PE surface. When the number was 24 and 32, it had little effect on the wettability of the PE surface. When the number of the graft chain was more than 48, it had more effect on the wettabillity of the PE surface. When the number of the graft chain monomer was 10-15, it had the best effect on the PE surface. 3．Dissipative particle dynamics simulation was performed to study surfactant adsorption on the surface of polymeric micelles in aqueous solution. The graft hydrophilic polymer could effectively prevent surfactant from adsorbing on the surface of micelles. If the length of the graft chain was unchanged and the number of the graft chain was between 2 and 5, 0．1667-0．4167 volume fraction of hydrophilic polymer, polymeric micelles could effectively prevent surfactant from adsorbing on their surface. It was effective for polymeric micelles to prevent surfactant from adsorbing on their surface when the length of the graft chain was longer than 4 beads.4．Dissipative particle dynamics simulation was performed to study the morphologies and rheological properties of surfactant adsorption on the surface of amphiphilic polymeric micelles in aqueous solution under various shear rates. Some important information on drug controlled released agent was proposed.更多还原