【作者】 赵强；

【导师】 成国祥；

【作者基本信息】 天津大学 ， 材料学， 2004， 硕士

【摘要】 聚(3-羟基丁酸酯)(PHB)是一种由细菌发酵而得到的脂肪族聚酯,其具有生物降解性、生物相容性和压电性等特点。同时,它也具有脆性严重、亲水性差、降解时间长等缺点。本文对PHB 的基本特性、PHB 的合成与提取方法、PHB 的改性以及PHB的应用等内容进行了较为详细的总结和评述。同时介绍了用于预防术后粘连的各种可吸收高分子材料。本研究引入了第二组分-聚乙二醇对其进行改性。PEG 作为材料的一部分,可以弥补PHB 在亲水性、降解性等方面的不足。为了从根本上改善PHB 的性能,特别是综合提高其力学性能、亲水性和降解性,本文采用多嵌段共聚的方法将两组分结合。具体的方式是先将PHB 制成具有特定分子量和端基的低分子预聚物,然后在偶联剂的作用下实现PEG 和PHB-diol 的共聚。并采用红外光谱、核磁共振、凝胶渗透色谱、示差扫描量热、偏光显微镜、接触角、力学实验机等对产物的结构和性能进行了表征。研究结果表明,采用酸催化下的醇解反应,可以制得具有特定端基和预定分子量的PHB 预聚物。在PHB-diol的偏光显微镜照片中观察不到明显的球晶形态。反应过程中PHB 分子链各处具有相同的反应几率,分子链无规断裂。采用HDI 作偶联剂,控制一定的反应条件可得到PHB/PEG 多嵌段共聚物。红外光谱和核磁共振证明了该共聚物的化学结构。产物的GPC 谱图表现为对称的单峰分布。在DSC 升温过程中,共聚物可以观察到明显的玻璃化转变,其转变温度比纯PHB 有大幅度降低。共聚物具有很高的韧性,其断裂伸长率可达150%左右。随PHB 含量的增加,共聚物的拉伸强度、杨氏模量提高,断裂伸长率下降。PEG的引入使材料的本体亲水性(溶胀率)显著改善,且随PEG 含量的提高而增加。同时,由于亲水性的改善,共聚物的降解速率较纯PHB 也有了大幅度提高。更多还原

【Abstract】 Poly(3-hydroxybutyrate) (PHB) is a aliphatic polyester produced by a number of bacteria. It has many special properties such as biocompatibility, biodegradability, piezoelectric property and so on. Meanwhile, PHB is fragile, hydrophobic and its degradation time is too long. In this thesis, the basic properties of PHB, the synthesis and purification of PHB, and its modification as well as the applications of it were expatiated. At the same time, the resorbable polymeric materials used to prevent postsurgical adhesions were also reviewed in detail. We introduce poly(ethylene glycol)(PEG) as a second component to modify PHB. The incorporation of PEG into a PHB matrix can improve the hydrophilicity, flexibility and degradation rate. In order to improve the properties of PHB in essence, especially to improve the mechanical properties, hydrophilicity and degradability, the approach taken in the effort described here is based on multiblock copolymers. The detailed synthesis process is as follows. First, natural-origin PHB of high molecular weight was degraded by alcohololysis to provide low molecular weight and dihydroxy-terminated prepolymers. Then PHB-diol and PEG were multiblock copolymerized with hexamethylene diisocyanate (HDI) as coupling agent. Characterization by means of NMR, IR, DSC, POM, GPC and so on was carried out. The results showed that the prepolymers with special end-groups and destined molecular weight could be prepared by the alcohololysis in the presence of acid as the catalyst. No clear spherulitic morphology was observed in polarizing optical micrograph of PHB-diol. In the process of reaction, the degradation of the polymer follows a random chain scission mechanism. Every part of the molecular chain has an equal reactive probability. Under certain conditions, PHB/PEG multiblock copolymers can be synthesized in the presence of HDI. The chemical structures of multiblock copolymers were confirmed by IR, 13C NMR. The GPC chromatographs of copolymers showed, in all cases, peaks which were unimodal. During the heating scan of copolymer, obvious glass transition was detected. In addition, the Tg value is much higher than that of pure PHB. The copolymers were of high toughness and its elongation rate at break can reach to 150%. The tensile strength, Yong’s modulus and elongation at break decreased with increasing the content of PHB-diol. The introduction of PEG dramatically improved the hydrophilicity (Swelling Ratio). And as the PEG content was increased, SW increased. By contrast to pure PHB, the degradation rates of copolymers were also raised by increasing the availability of water within the matrix.更多还原