【作者】 梁敬翠；

【导师】 孔祥正；

【作者基本信息】 济南大学 ， 高分子化学与物理， 2010， 硕士

【摘要】 在超临界CO2介质中用沉淀聚合法成功地合成了表面光滑的、单分散的二乙烯基苯聚合物(PDVB)微球、二乙烯基苯(DVB)和马来酸酐(MAH)共聚物(P(DVB-MAH))微球及三羟甲基丙烷三丙烯酸酯聚合物(PTMPTA)微球。研究了单体浓度、反应时间、反应压力、反应温度、共溶剂种类、共溶剂用量、引发剂浓度、单体配比等反应条件对聚合反应结果的影响;通过扫描电镜(SEM)对产物的形貌进行了观察,并探讨了聚合物微球的成长过程及成球机理;利用红外光谱(IR)对所得聚合物的结构进行了表征;利用热失重(TG)对聚合物进行了热性能分析;采用溴滴定法对单分散PDVB微球中的悬挂双键进行了测定。实验发现,在超临界CO2介质中能够直接得到粉末状的PDVB、P(DVB-MAH)及PTMPTA,且单体的转化率都到了97%以上。研究发现,在纯超临界CO2介质中很难获得PDVB、P(DVB-MAH)及PTMPTA的微球,而加入少量共溶剂(如正戊烷、乙酸、乙醇、丙酮等),在合适的反应条件下可以制得上述聚合物微球。因此,选择适当极性的共溶剂以及反应浓度、反应压力等条件来调节反应介质的溶解度参数是制备单分散聚合物微球的重要条件。研究表明,在少量丙酮作为共溶剂的超临界CO2体系中,当单体浓度为0.38 mol/L、反应压力为16.0 MPa、反应时间为24 h、混合溶剂的溶解度参数在10.58~11.01 MPa1/2范围时得到了表面光滑的、单分散的PDVB微球,并且聚合体系的单体浓度、反应压力及共溶剂用量对单体的转化率以及聚合物的热性能影响不大,但是对聚合物的成球性有很大影响。当MAH摩尔分数为5%~10%时也得到了表面光滑的、分散较好的P(DVB-MAH)共聚物微球,红外谱图表明我们成功地合成了MAH含量较高的P(DVB-MAH)共聚物。在少量乙醇为共溶剂的超临界CO2体系中,当单体浓度为0.067 mol/L、反应压力为16.0 MPa、反应时间为8 h时得到了PTMPTA微球。采用溴滴定法测定了PDVB微球中悬挂双键的含量,并通过红外谱进行了表征。通过比较溴加成前后及溴消去后的聚合物红外谱图证明了PDVB微球中确有悬挂双键的存在,通过溴滴定曲线得到了PDVB微球中悬挂双键的总量为2.99×10-3 mol/g,微球表面悬挂双键的量为1.81×10-3 mol/g,证明所制备的单分散PDVB微球含有大量的未反应的双键,利用这些双键可以进一步进行改性反应,从而对微球进行功能化,具有广泛的应用前景。更多还原

【Abstract】 In this paper, monodisperse micro-size polydiviylbenzene (PDVB) microspheres, poly diviylbenzene-co-maleic anhydride (P(DVB-MAH)) microspheres and polytrihydroxy methylpropane triacrylate (PTMPTA) microspheres with clean surfaces were synthesized by precipitation polymerization in supercritical carbon dioxide system. Influences of monomer concentration, reaction time, reaction pressure, reaction temperature, species of cosolvent, the dosage of cosolvent, initiator concentration and monomer ratio on morphology and size of polymers were investigated; the morphology of the polymers were observed via scanning electron microscopy (SEM). The growth of polymer microsphere and the mechanism of polymer microsphere formation were also discussed; at the same time, the structure of polymers was characterized by IR and thermal property of polymers was determined by TDA. The total amount of detected vinyl groups in PDVB microspheres was determined by bromine titration.Results demonstrated that PDVB, P(DVB-MAH) and PTMPTA were white powder solid and the conversions in all polymerization systems were above 97 %. It was found difficult to prepare PDVB, P(DVB-MAH) or PTMPTA microspheres in pure supercritical carbon dioxide, but monodisperse microspheres of these polymers were obtained in supercritical carbon dioxide with an amount of cosolvent (for example: n-pentane, acetic acid and acetone). Therefore, selecting the proper cosolvents and reaction pressure, reaction concentration to adjust solubility parameters of reaction medium were important in preparing monodisperse polymer microspheres.The results showed that monodisperse PDVB microspheres were obtained with monomer concentration of 0.38 mol/L, reaction pressure of 16.0 MPa and reaction time of 24 h, solubility parameters of reaction medium of 10.58~11.01 MPa1/2 in supercritical carbon dioxide using appropriate acetone dosage. It was also demonstrated that monomer concentration, reaction time, reaction pressure and cosolvent had no effect on the appearance, conversions and thermal property, but had a pronounced effect on morphology of the polymers. At the same time, P(DVB-MAH) microspheres were also prepared with MAH loading of 5 mol % ~10 mol %; the structures of copolymers were characterized by IR and the content of MAH in the copolymers was relatively high. PTMPTA were producted with monomer concentration of 0.067 mol/L, reaction pressure of 16.0 MPa and reaction time of 8 h in supercritical carbon dioxide using appropriate ethanol dosage system.In this experiment, the residual double bonds of the polymer microspheres were also determined by bromine addition and were characterized by IR. The presence of the residual double bonds in polymer microspheres was comfirmed via comparing the IR spectra of the polymers prior to and after bromine addition and elimination in the microspheres. The content of residual double bonds in polymer microspheres was determined by bromine titration. The results showed that the total amount of the residual double bonds in the microspheres was about 3.0×10-3 mol/g and the amount of the residual double bonds at the microspheres surfaces was about 1.8×10-3 mol/g. The PDVB microspheres, which have relatively high concent of residual double bonds, can be further functionalized.更多还原