【作者】 刘海峰；

【导师】 王玉荣；

【作者基本信息】 大连理工大学 ， 材料学， 2006， 硕士

【摘要】 由于结构上的特殊性,异丁烯的聚合物具有优良的耐老化性、弹性和气密性,在轮胎和密封材料中的应用有不可替代性。而星形支化异丁烯系聚合物,由于其独特的物理化学属性和支化结构,可以在保持低的熔体和溶液粘度的同时得到高分子量的聚合物,即物理机械性能和加工性能的统一,一直是异丁烯阳离子科研工作者研究的热点之一。但异丁烯只能阳离子聚合,而能阳离子聚合的单体比较有限,因此利用阳离子聚合与其它聚合技术相结合的方法,是合成新颖结构和优异性能的异丁烯共聚物产品的一个重要研究方向。 本文首先采用活性阴离子聚合技术,以环己烷为溶剂,n-BuLi为引发剂,苯乙烯、异戊二烯和丁二烯为单体,THF为调节剂,采用不同的偶联剂,合成了制备星形支化异丁烯聚合物所用的多官能团大分子接枝剂Poly（St-b-Ip）和Poly（St-b-Bd）,GPC分析表明:凝胶渗透色谱对星形聚合物及未反应的线性部分进行了非常有效的分离,偶联效率较高,设计分子量与实验值吻合;。¹HNMR分析表明:星形大分子中的单体配比与设计值相符,聚苯乙烯链中非嵌段的含量很小,嵌段效率较高。 通过阴离子聚合向阳离子聚合转换的方法,在-90℃下,采用阳离子聚合技术,以一氯甲烷为溶剂,H₂O/AICl₃为引发体系,异丁烯和异戊二烯为单体,Poly（St-b-Ip）和Poly（St-b-Bd）为大分子接枝剂,首次合成了一种每个星形大分子臂上接枝几个聚异丁烯链或丁基胶链的新型支化异丁烯系聚合物。GPC分析表明:聚合物呈双峰结构,有部分的超高分子量的聚合物生成,且分子量分布明显变宽;FTIR分析表明:加入星形大分子接枝剂后,在696cm^-1附近出现了聚苯乙烯的苯环特征吸收峰;¹HNMR分析表明:无论星形大分子加入的顺序如何,其上的双键都已成功的被打开,接枝上了聚异丁烯链,接枝效率均在80%左右;所得星形支化聚异丁烯和丁基橡胶的高分子量区的含量,可以通过控制星形大分子的加入量而加以控制。高分子量区级分的分子量可以通过控制星形大分子的可反应性双键的数量和反应活性而加以控制。 考察了星形支化丁基橡胶的生胶强度与应力松弛之间的关系,结果表明,这种具有部分超高分子量的星形分支结构和小分子量的线性分支结构的丁基橡胶能够提供较高的初始强度和较快的应力松弛。更多还原

【Abstract】 Polyisobutylene and its copolymers are noTab. for their good aging and low permeability air, and cannot be substituted in the sealant and rubber industry because of their special structure. Moreover, star-branched isobutylene-based polymers have been extensively studied for a long time due to their markedly lower solution, bulk viscosities and less shear sensitivity. At the same time, isobutylene can only be polymerized by cationic polymerization, and there are few monomers like that. Therefore, the combination of cationic polymerization and other living polymerization techniques is a very important method to synthesize novel structure and performance polymers.In this studies, the star-shaped multifunctional Poly（St-b-Ip） and Poly（St-b-Bd） copolymers were synthesized in the present of n-BuLi as initiator, THF is used as polar modifier, SiCl₄, SnCl₄ and DVB as coupling agent, cyclohexane as solvent by living anionic polymerization. The GPC results show that the chromatogram reveals a large, well-defined separation between the star and residual arm fraction, and the coupling efficiency is higher. The ¹HNMR results show that the designed St/Ip and St/Bd in the star polymers accord with the experimental values. The amount of non-block of polystyrene is very small, and the block efficiency is higher.A novel branched polymer that each arm of star-shaped Poly（St-b-Ip） and Poly（St-b-Bd） contained several polyisobutylene or butyl rubber chains was first prepared in the present of H2O/AlCl₃ initiating system, CH₃Cl as solvent by combination of cationic polymerization and living anionic polymerization in -90℃. The GPC indicates that the polymer produced has a bimodal molecular weight distribution with a high molecular weight branched mode and a low molecular weight linear component;the FTIR indicates that the peak is due to the out-of-plane C-H bends of the aromatic ring at 696cm¹;the ¹HNMR results show that the polyisobutylene chains have successfully grafted on the star-shaped polymers whatever the adding order, and the grafted efficiency is almost 80%. The amount of the high ends fraction of star-branched polyisobutylene and butyl rubber can be controlled by the amount of the reactive star polymer added;the molecular weight of the amount of the high ends fraction can be controlled by the amount and reacticity of the functionality on the reactive star polymer.The green strength and stress relaxation of star-branched butyl rubber are also studied. The results show that the star-branched butyl rubber with a high molecular weight branchedmode and a low molecular weight linear component has a higher green strength and faster relaxation stress.更多还原