【作者】 刘纯；

【导师】 王东军；

【作者基本信息】 河北科技师范学院 ， 应用化学， 2010， 硕士

【摘要】 在反应体系沸腾的状态下,以偶氮二异丁腈为引发剂,在不加任何乳化剂或稳定剂且无搅拌的情况下,制备了单分散牡丹花状聚丙烯腈微球。用透射电子显微镜、扫描电子显微镜、X-射线衍射仪、激光粒度分析仪和红外光谱仪等测试方法对乳胶粒子形态与聚合物结构进行了表征,发现每个聚合物颗粒都是由一定数目的片层组成,片层厚度大约为10 nm。本文系统研究了聚合反应的特征及牡丹花状聚合物微球的形成机理。探讨了单体与分散介质配比、引发剂浓度、反应时间、分散介质、共聚单体和搅拌等因素对聚合物微球形貌及大小的影响。单体与分散介质体积比在一定的范围内(1:30-1:5)时,可以制备出单分散性聚丙烯腈微球,随着单体比例的增加聚合物微球粒径增大,表面片层数目增加。反应体系在沸腾状态下反应2 h是其最佳反应时间,延长反应时间聚合物微球的单分散性下降,出现多种形貌的聚合物颗粒。在不同沸点的酯类分散介质中分别进行丙烯腈的聚合反应,得到了不同形貌和粒径的聚合物微球。随着介质沸点的升高,聚合物微球的表面凸起越来越不明显,规整性越来越好,粒径越来越小。以乙酸丁酯为分散介质时,聚合反应速率很快,10 min后聚合物微球的粒径基本不再变化,并且整个反应过程中,聚合物微球形貌基本一致。共聚单体苯乙烯的加入对聚合物微球形貌及粒径产生很大影响。在反应体系中加入极少量的苯乙烯,聚合物微球表面便观察不到片层结构,只有轻微褶皱。增加苯乙烯的用量,聚合物颗粒成为表面光滑、球形度好的微球。当苯乙烯的含量增大到一定量时,微球之间便会发生粘连。聚合物微球粒径随着苯乙烯含量的增加而增大,单分散性比纯聚丙烯腈微球好。X-射线衍射测试结果表明苯乙烯的加入降低了聚合物微球的结晶性能。更多还原

【Abstract】 Monodisperse peony-like polyacrylonitrile microspheres were prepared by a one-step approach in the presence of azodiisobutyronitrile as initiator without adding any stabilizer and mechanic stirring under reflux condition. Surface and structure characterizations of the particles were performed by methods such as transmission electron microscopy, scanning electron microscopy, X-ray diffraction, laser scattering particle size distribution analyzer and infrared spectrum. The results showed that the pure PAN microspheres are constructed by a number of nanoflakes, which thickness is around 10 nm. This paper systematically studied the polymerization characteristics and formation mechanism of peony-like polymer microspheres. The influence of various polymerization parameters (e.g., concentration of monomer, initiator and comonomer, time of polymerization, type of dispersion medium and mechanic stirring) on the properties (e.g., morphology, size and size distribution, etc.) of the particles has been investigated.The monodisperse polyacrylonitrile microspheres can be synthesized over a relatively wide range of monomer concentration. With the enhancement of monomer concentration, the size of polymer particles and the number of nanoflakes increased. The optimal reaction time was 2 h in the boiling medium. With the extension of reaction time, the size distribution of the particles was affected and there were kinds of particles with different morphology.The polymerization of acrylonitrile was operated in several kinds of esters with different boiling point. The polymer microspheres with different morphology and size were obtained. The results showed that the higher the boiling point of dispersion medium was, the more unapparent the extensions of the microspheres morphology became, the better the regularity became and the less the size was. In butyl acetate, the polymerization was a relatively rapid process. About 10 minutes later, the size of polymer microspheres hardly changed, and in the whole process the microspheres almost had the same morphology.Copolymerization with styrene affected greatly the morphology and size of the polymer microspheres. Adding a spot of styrene, the nanoflakes which constituted polymer particles disappeared, and the surface of the particle was only a little uneven. The larger the concentration of the styrene increased, the smoother the morphology of particles became and the better the sphericity of particles was. But increasing the styrene concentration above certain amount resulted in agglomeration. The size of particles increased with increasing the concentration of styrene, and the size distribution was better than pure polyacrylonitrile microspheres. The X-ray diffraction result indicated that adding styrene decreased the crystallinity degrees of polyacrylonitrile更多还原