【作者】 肖楠；

【导师】 杨万泰；

【作者基本信息】 北京化工大学 ， 材料科学与工程， 2013， 硕士

【摘要】 可控活性自由基聚合既有着阴离子聚合的活性特征，同时兼有着传统自由基聚合易于实现的特点，是目前合成设计精准可控聚合物最有效的方法之一。经过30多年的发展，活性自由基聚合技术已经取得了许多突破性的进展，目前对于活性自由基聚合体系的研究主要集中在使用含C-X(X=O，S，卤素，金属化合物等)封端基的体系，对含C-C可断裂偶合的体系研究较少。本文通过自由基偶合法，设计合成了2-氧杂蒽醇-2-甲基丙腈(2-(9-hydroxy-9H-xanthene)-2-methyl-propionitrile，XNMPN)引发剂，通过不同条件的对比确定了最佳合成条件为60℃，反应24小时，Bixan：AIBN约1:1.2。通过改变不同条件，研究了以XNMPN为引发剂本体聚合MMA的效果。结果显示，聚合物分子量随着转化率增加而增加，聚合反应符合一级动力学反应，符合活性聚合特征。不同温度以及不同引发剂用量对于聚合反应的控制有较大影响，当温度为55℃XNMPN用量为0.5wt%时，可得到分子量为34×104，分子量分布为1.5的PMMA。本文还研究了不同溶剂以及不同条件下MMA溶液聚合的效果。结果显示，不同的聚合环境对于XNMPN的分解速率有较大影响，三种不同溶剂中的聚合速率为：四氢呋喃>甲苯>苯甲醚。当溶剂为四氢呋喃，温度为45℃，XNMPN用量为0.25wt%时，所得到的PMMA分子量分布可低至1.4左右。初步探索了大分子聚合物作为引发剂进行扩链反应的效果。根据聚合的GPC谱图发现，聚合物峰有明显左移的同时还有较为明显的拖尾或是双峰现象，且拖尾处与大分子引发剂处重合，再结合聚合物紫外可见光谱图以及XNMPN，Bixan中半频哪醇结构的紫外出峰标准曲线计算，可以判定部分大分子引发剂含有较多的无活性聚合物，只有部分聚合物扩链成功。更多还原

【Abstract】 In the early1980s, polymer chemists became interesting in a type ofradical polymerization called living/controlled radical polymerization (LRP),which would possess the living polymerization features similar to anionicpolymerization while keeping the advantages of the conventional radicalpolymerization methods. Presently, most LRP methods are based on C-X(X=O, S, halogen, etc.) bond mediated systems. And almost no attention arepaid on the simple C–C weak bond systems which can mediate polymerizationby reversible dissociation/combination (DC).In this study, we utilized BIXANDL and AIBN which could produceradicals and mutually couple under thermal to design and synthesis of a novelinitiator XNMPN. The optimal synthetic conditions were determined by thecomparison of the different conditions.Bulk polymerization of MMA initiated by XNMPN under differentconditions was investigated. The results showed that polymerization reactionfitted a first order reaction. The molecular weight of PMMA increased withreaction time, indicating a living/controlled radical polymerization feature.When the polymerization was carried out in XNMPN=0.25wt%at55℃,PMMA with a narrow PDI of1.5could be obtained.This paper also studied the effects on solution polymerization of MMAunder different solvents and different conditions. The experiment indicatedthat decomposition rate of XNMPN would be great influenced by differentsolvents, and rate followed an order as tetrahydrofuran> toluene> anisole.When the polymerization was carried out in tetrahydrofuran at45℃with aratio of XNMPN to MMA=0.0025:1, PMMA with a molecular weight of7.3×104and a PDI of1.4was obtained.Polymer chain extension was preliminary investigated by using macromolecular as extender. The results of GPC curves of polymer showedthat the molecular weight peaks had left shift with increasing conversion,which meant chain extension was clearly occurred.更多还原