【作者】 刘峻；

【导师】 原续波；

【作者基本信息】 天津大学 ， 材料学， 2006， 硕士

【摘要】 生物可降解塑料代替现有的不可降解塑料,对于保护环境,减少污染具有十分重要的意义。聚3-羟基丁酸酯(PHB)作为一种生物可降解塑料,目前主要采用生物发酵法生产,价格昂贵,限制了它的推广应用。采用化学法合成PHB均聚物及共聚物可以降低生产成本、调整聚合物的结构和改善聚合物的性能。本文对采用化学法制备PHB均聚物及共聚物进行了探索。以3-羟基丁酸乙酯,3-羟基丁酸为单体,通过缩合聚合法制备PHB均聚物。以1H NMR对原料和产物进行了表征。结果表明,原料和产物中均有巴豆酸存在,巴豆酸在缩聚反应中起到端基封锁的作用,采用这种方法不能制备高相对分子质量的PHB。以巴豆酸为原料,溴化氢加成反应制备3-溴丁酸;3-溴丁酸发生分子内反应制备β-丁内酯。利用1H NMR和FTIR表征产物结构。以四丁基醋酸铵为引发剂,β-丁内酯为单体进行阴离子开环聚合制备PHB均聚物。考察了反应时间,反应温度和聚合方法对PHB均聚物相对分子质量的影响。1H NMR、13C NMR及ESI-MS测试证明β-丁内酯开环形成PHB均聚物。13C NMR分析表明PHB均聚物分子链的构型为无规构型,引发剂四丁基醋酸铵对单体没有构型选择能力。以四丁基醋酸铵为引发剂,β-丁内酯与L-丙交酯为单体进行了阴离子开环聚合制备共聚物。1H NMR、DSC测试证明四丁基醋酸铵可以引发β-丁内酯与L-丙交酯共聚,共聚反应中L-丙交酯的开环反应活性高于β-丁内酯。13C NMR分析表明,共聚物中重复单元序列分布不符合伯努利统计。更多还原

【Abstract】 Biodegradable plastics have great significances in the field of environment protecting. As one kind of biodegradable plastic, poly(3-hydroxybutyrate) (PHB) have been produced by biological ferment presently. But the price is so high that it can not be used widely. PHB synthesized by chemical method, however, will reduce the cost and improve the property by adjusting polymer’s structure. The purpose of this paper is to study the chemical synthesis route of producing PHB.In this paper, ethyl 3-hydroxybutyrate and 3-hydroxybutyric acid were firstly used to synthesize PHB by means of condensation polymerization respectively. The product was characterized by 1H NMR and the results showed that crotonic acid was mixed in the reactant resulting in the lower molecular weight of resultant PHB. So PHB with high molecular weight can not be synthesized in this way.In this paper, crotonic acid was also chosen as raw material to synthesize PHB. Crotonic acid was firstly reacted with HBr to synthesize 3-bromobutyric acid. Thenβ-butyrolactone was obtained by ring-closing reaction of 3-bromobutyric acid. 1H NMR and FTIR measurement demonstrated the formation ofβ-butyrolactone. Based on these, anionic ring-opening polymerization ofβ-butyrolactone was performed using tetrabutylammonium carboxylates(TBA acetate) as initiator. The influences of reaction time, reaction temperature and polymerization method on molecular weight of PHB were studied. 1H NMR, 13C NMR and ESI-MS were utilized to identify the structure of PHB obtained. The analysis of 13C NMR indicated that the configuration of PHB was atactic and TBA acetate had no capability of controlling configuration of the repeating unit.TBA acetate was also used to initiate the anionic ring-opening copolymerization ofβ-butyrolactone and L-lactide. 1H NMR, 13C NMR and ESI-MS were also utilized to identify the structure of copolymer. The analysis of 1H NMR showed that the ring-opening reaction of L-lactide occurred more easily thanβ-butyrolactone. 13C NMR indicated that the repeating unit of copolymer did not follow the Bernoullian statistic.更多还原