可降解聚氨酯水凝胶的制备及性能研究

	可降解聚氨酯水凝胶的制备及性能研究
	薛飒飒
导师	万晓波 ; 宫瑞英
	2016-05-24
学位授予单位	中国科学院大学
学位授予地点	北京
学位专业	材料工程
关键词	水凝胶聚氨酯聚乳酸聚己内酯可降解机械强度
摘要	聚氨酯水凝胶兼具水凝胶和聚氨酯的优点，是一类具有良好的亲水特性和机械性能，同时具有三维网络交联结构的高分子聚合物。它可以吸收大量水分溶胀而不溶于水，可以通过改变聚氨酯分子链中软硬段组成比例调节所得水凝胶的性能，是一类应用前景非常广阔的新型功能材料。目前制备聚氨酯水凝胶的方法大多是将合成的聚氨酯预聚体在特定条件下固化形成三维网状结构的膜，然后将其浸入水中，吸水形成水凝胶。用这种方法制备的水凝胶的含水量较低，或者在较高含水量条件下其机械强度往往很低。另外，随着人们环保意识的提高、生产和生活方面对新型功能材料的需求，可降解的聚氨酯水凝胶引起了人们广泛的关注，因此高强度高保水量的可降解聚氨酯水凝胶的制备迫在眉睫，但若要同时满足这三大性能，仍然是一项很大的挑战。本论文旨在对可降解聚氨酯水凝胶的研究，以期实现高强度，高保水量和可降解的目标。具体研究内容及结果如下： 1. 基于聚左旋乳酸（PLLA）和聚乙二醇（PEG）为软段的可降解聚氨酯水凝胶的合成与性能研究：采用共聚和共混两种方法将PLLA，PEG引入聚氨酯主链，生成聚氨酯预聚体，与水混合形成水凝胶，以期达到高强度、高保水量、可降解的目标。结果表明，共混法可以实现以上目标，而共聚法却不能。共混法制备聚氨酯水凝胶的方法与已报道的方法相比具有快速、简单、易行等优势，有利于大规模的使用，具有很好的应用前景。我们探究了水凝胶的形成机理，结果表明制备的可降解聚氨酯水凝胶是以物理交联和化学交联的方式形成三维网络结构；同时研究了三臂聚左旋乳酸（3-armed-PLLA）的分子量，PEG的分子量以及两者的质量比对聚氨酯水凝胶拉伸强度的影响，得出基于PLLA，PEG为软段的聚氨酯水凝胶的最佳配方。所制备的水凝胶的最大含水量为97.4%，在含水量为91%的情况下，拉伸强度达到108 KPa，断裂伸长率为1570%。进一步借助万能材料测试机和扫描电镜（SEM）对聚氨酯水凝胶在PBS缓冲溶液中的降解性能进行了研究，制备的聚氨酯水凝胶不仅具有很好的机械强度和伸缩性，同时还具有可降解性，实现了高强度，高保水量，可降解的目标。 2. 基于聚己内酯（PCL）和PEG为软段的可降解聚氨酯水凝胶的合成与性能研究：在前面工作的基础上仍然采用共混的方法制备聚多元醇，不同的是将3-armed-PLLA换成了四臂聚己内酯（4-armed-PCL），按照同样的制备方法制备了水凝胶，其最大含水量为97.56%，在含水量为91%的情况下，拉伸强度达到233.6 KPa，断裂伸长率为3043%。对比结果表明，将强极性的PLLA换成了柔性链段较长的PCL，同时增加了交联点，使所制备的水凝胶具有更高的拉伸强度和弹性。这些研究对制备高强度高保水量的可降解聚氨酯水凝胶具有一定的借鉴意义。
其他摘要	Polyurethane(PU) hydrogel, which combines the advantages of hydrogel and polyurethane, is a crosslinked polymer which can absorb large amounts of water but insoluble in water, and it is expected to be a new kind of functional materials. Its properties can be modified through changing the ratio between soft segment and hard segment in the molecular chain. Biodegradable polyurethane hydrogels have attracted considerable research interest due to their superior biocompatibility. For hydrogel formation, most of the reported PU hydrogels were prepared with a post-absorption method: the PU prepolymer was cured under the suitable conditions to form the three-dimensional hydrophilic networks first, and then this network was immersed into water to form hydrogel. The water content for the hydrogel prepared by this method is generally low, moreover, for the resultant hydrogel, its mechanical strength is also low at high water content, which makes it not suitable for applications which requires mechanically strong and high water content hydrogels. It seems that to obtain a biodegradable PU hydrogel with both excellent mechanical properties and high water content is a dilemma. This study is aimed to prepare a biodegradable PU hydrogel with both excellent mechanical properties and high water content. In the first part of this study, we prepared a biodegradable PU hydrogel based on poly(L-lactic acid) (PLLA) and polyethylene glycol (PEG). Briefly, 3-armed-PLLA and linear PEG were end-capped with isocyanate and then mixed to form a PU prepolymer, which could form hydrogels when mixed with water. This method to prepare hydrogel is simple and fast, which might be used in extensive applications. The mechanism to form the hydrogel is investigated, which shows that it is physically and chemically crosslinked to form the three-dimensional network. The effect of the molecular weight and the feeding ratio of 3-armed-PLLA and PEG on the tensile property of PU hydrogels is discussed. The resulting hydrogel shows good mechanical properties with high tensile strength (up to 108 KPa) and elongation rate (1570%), while maintaining high water content (up to 91% mass ratio). The maximum water content of the hydrogel was 97.4%. Furthermore, the resultant hydrogel is biodegradable. In the second part of this study, we prepared another biodegradable PU hydrogel based on polycaprolactone (PCL) and PEG. The PU hydrogel is obtained from PEG and 4-armed-PCL in a similar way as the PLLA-based PU hydrogel mentioned in the first part and it shows better tensile strength (up to 233.6 KPa) and elongation rate (3043%) at 91% of water content than previous hydrogel, and the maximum water content of the hydrogel was 97.56%. This indicates that the increasing of crosslink points and the introduction of more flexible segments contributed more to the tensile strength and higher elasticity of hydrogel. These findings might cast light on the design of biodegradable PU hydrogels with both excellent mechanical properties and high water content.
作者部门	生物基及仿生高分子材料团队
学科领域	材料工程
公开日期	2020-06-30
学位类型	硕士 ; 学位论文
语种	中文
文献类型	学位论文
条目标识符	http://ir.qibebt.ac.cn/handle/337004/9784
专题	生物基及仿生高分子材料团队（过去）
作者单位	中国科学院大学
推荐引用方式 GB/T 7714	薛飒飒. 可降解聚氨酯水凝胶的制备及性能研究[D]. 北京. 中国科学院大学,2016.

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