摘 要

水凝胶是一种亲水性高分子聚合物，它具有优异的生物相容性。由于水凝胶具有三维网络结构，因此它的应用非常广泛，例如用于药物载体、伤口敷料、组织工程等领域。但是在实际的使用过程中，单独使用某一种水凝胶时，由于它们各自的性能缺陷，使得其与人体环境不能良好的匹配。通过多种聚合物的复合，从而改善了它们在单独使用存在的性能缺陷。海藻酸钠（SA）、聚乙烯醇（PVA）是高分子聚合物材料，它们具有较好的生物相容性，因此经常被应用于水凝胶的研究开发。在本课题中，将海藻酸钠和聚乙烯醇的混合溶液放置于恒温水浴锅中保温12h，交联成胶，然后进行数次的冷冻-解冻循环后制备得到海藻酸钠/聚乙烯醇复合凝胶。本课题的研究目的在于以海藻酸钠和聚乙烯醇为原料，通过两步交联法制备得到具有特定微观结构的水凝胶。研究水凝胶的溶胀和力学等性能，以及复合比、原料浓度、交联剂用量和交联反应时间等工艺参数与水凝胶的溶胀和力学性能之间的构效关系，得到最佳的制备工艺。本课题有望提升同类水凝胶的力学、溶胀度等性能，从而满足实际应用需要。本论文的结论如下：

通过FTIR和SEM表征表明水凝胶制备成功并具有良好的网络结构。对水凝胶的溶胀性、力学性能、pH敏感性和降解性能进行测试，结果表明：海藻酸钠/聚乙烯醇水凝胶的溶胀性能随着聚乙烯醇含量的增加而下降，随着海藻酸钠浓度、交联剂用量的增加先下降后上升，随着冷冻-解冻循环次数的增加先上升后下降再上升，水凝胶具有一定的pH敏感性，在pH=7.4缓冲溶液中溶胀度大于在pH=1.0缓冲溶液中溶胀度。水凝胶的力学性能良好，并随着聚乙烯醇含量、冷冻-解冻循环次数增加，抗压强度先上升后下降，最大抗压强度达到0.28MPa。选取七个pH值，研究了水凝胶的pH敏感性，结果表明水凝胶具有良好的pH敏感性。水凝胶的降解性能良好，并随着聚乙烯醇含量增加，降解性能逐渐下降。

关键词：水凝胶；海藻酸钠；聚乙烯醇；冷冻-解冻循环

Abstract

Hydrogel is a kind of hydrophilic macromolecule polymer with excellent biocompatibility. Because of its three-dimensional network structure, hydrogel is widely used, such as in drug carriers, wound dressings, tissue engineering and other fields. However, if one type of hydrogel is used alone, it does not match the human environment due to their respective performance defects. By combination of a variety of polymers, thereby improving their performance in the presence of separate defects. Sodium alginate (SA) and polyvinyl alcohol (PVA) are both polymer materials, which have good biocompatibility, so they are often used in the research and development of hydrogel. In this paper, we mix the solution of sodium alginate and polyvinyl alcohol, then place it in a constant temperature water bath for 12h. Until it is crosslinked, several freezing-thawing cycles are carried out to obtain sodium alginate / polyvinyl alcohol hydrogel. We use sodium alginate and polyvinyl alcohol as raw materials in this study, then hydrogel with specific microstructure were successfully prepared by using two step crosslinking method. We also explore the swelling and mechanical properties of this hydrogel , and the parameters such as composite ratio，raw material concentration , amount of crosslinking agent and reaction time were also investigated, then obtained the best preparation process. In this study, we are expected to improve the mechanical and swelling properties of hydrogel, thus meeting the needs of practical application. Conclusions of this paper are as follows:

FTIR and SEM characterizations showed that the SA/PVA hydrogel was successfully synthesized and had good network structure. And the swelling properties, mechanical properties, pH-sensitivity, degradability were tested. The results indicated that the swelling properties of hydrogel decreased with the increased of the concentration of PVA, the swelling properties of hydrogel decreased firstly after rising with the increase of the concentration of SA and the amount of cross-linking agent, the swelling properties of hydrogel increased firstly after declining and finally increased with the increase of the frequency of the freezing-thawing cycle. The hydrogel had a certain pH-sensitivity, and the swelling degree in the buffer solution with pH=7.4 was larger than in pH=1.0 buffer solution. The mechanical properties of hydrogel were better, which increased firstly after declining with the increased of the concentration of PVA and the frequency of the freezing-thawing cycle, and the highest mechanical degree reached 0.28MPa. The pH-sensitivity of hydrogel was studied in the solution of seven pH values which show that the hydrogel was pH-sensitivity. The degradability of hydrogel was better, which decreased with the increased of the concentration of PVA.

Key words：Hydrogel; Sodium alginate; Polyvinyl alcohol; Freezing-thawing cycle

目录

摘 要 I

Abstract II

第1章 绪论 1

1.1 水凝胶 1

1.2 海藻酸钠水凝胶 1

1.2.1 海藻酸钠的结构与性质 2

1.2.2 海藻酸钠水凝胶的制备 3

1.2.3 海藻酸钠水凝胶的应用 4

1.3 聚乙烯醇水凝胶 5

1.3.1 聚乙烯醇的结构与性质 5

1.3.2 聚乙烯醇水凝胶的制备 6

1.3.3 聚乙烯醇水凝胶的应用 6

1.4 研究意义和内容 7

1.4.1 研究意义 7

1.4.2 研究内容 7

第2章 海藻酸钠/聚乙烯醇水凝胶的制备及性能研究 8

2.1 实验部分 8

2.1.1 试剂与仪器 8

2.1.1.1 实验试剂 8

2.1.1.2 实验仪器 9

2.1.2 海藻酸钠/聚乙烯醇水凝胶的制备 9

2.1.3 海藻酸钠/聚乙烯醇水凝胶的表征 9

2.1.3.1 海藻酸钠/聚乙烯醇水凝胶的红外表征（FTIR） 10

2.1.3.2 海藻酸钠/聚乙烯醇水凝胶的形貌表征（SEM） 10

2.1.3.3 海藻酸钠/聚乙烯醇水凝胶的热性能测试 11

2.1.4 海藻酸钠/聚乙烯醇水凝胶的溶胀性能测试 11

2.1.5 海藻酸钠/聚乙烯醇水凝胶的力学性能测试 11

2.1.6 海藻酸钠/聚乙烯醇水凝胶的pH敏感性能测试 11

2.1.7 海藻酸钠/聚乙烯醇水凝胶的降解性能测试 11

2.2 结果与讨论 12

2.2.1 海藻酸钠，聚乙烯醇和水凝胶的FTIR 12

2.2.2 海藻酸钠/聚乙烯醇水凝胶的SEM 12

2.2.3 海藻酸钠/聚乙烯醇水凝胶的TG/DTG 13

2.2.4 海藻酸钠/聚乙烯醇水凝胶的溶胀性能 14

2.2.4.1 聚乙烯醇含量对水凝胶溶胀性能的影响 14

2.2.4.2 海藻酸钠浓度对水凝胶溶胀性能的影响 16

2.2.4.3 交联剂用量对水凝胶溶胀性能的影响 17

2.2.4.4 冷冻-解冻循环次数对水凝胶溶胀性能的影响 19

2.2.5 海藻酸钠/聚乙烯醇水凝胶力学性能 20

2.2.5.1 聚乙烯醇含量对水凝胶力学性能的影响 20

2.2.5.2 冷冻-解冻循环次数对水凝胶力学性能的影响 21

2.2.6 海藻酸钠/聚乙烯醇水凝胶pH敏感性能 22

2.2.7 海藻酸钠/聚乙烯醇水凝胶降解性能 23

第3章 结论 25

致谢 26

参考文献 27

第1章 绪论

1.1 水凝胶

生物材料（或称为生物医学材料）是指对生物体进行医疗，用于与生物组织相接触以形成特殊功能的生命材料。生物材料科学的研究涉及面极其广泛，隶属于高科技领域^[1]。在当今二十一世纪，生物技术蓬勃发展并取得重大突破，临床方面有巨大的需求，在这样的环境条件下，生物材料已然成为各国科学家的研究热点，生物材料产业也在世界范围内发展迅猛，成为各国经济的一项支柱性产业。

在20世纪70年代，Tanaka等人^[2]发现在特定条件下，水凝胶发生溶胀，进而体积发生变化。在这一发现之后，水凝胶便真正进入了人们的视野，并越来越多的受到人们的关注。水凝胶是一种亲水性聚合物，能在水中溶胀，但是不溶解，因此能被广泛的应用。例如用作药物载体时，在特定的环境下，水凝胶溶胀继而促使药物释放，以达到控制药物释放速度的效果（药物缓释）。用作伤口敷料，在使用时水凝胶与人体组织接触，由于水凝胶的亲水性，可以使氧气通过，也可以防止体外细菌的感染，吸收分泌出的体液，从而促使新组织的生长。用作组织工程，有些水凝胶的力学性能不好，局限了其的应用，通过与其他材料的复合，从而增强了它的力学性能，在实际应用中代替人体软骨、肌腱等。由于水凝胶具有优异的性能，其技术发展有很大的进步空间，在未来应用方面具有巨大的潜力，引起了各国学者的热议^[3]。