【作者】 张帅；

【导师】 魏浩；

【作者基本信息】 哈尔滨工程大学 ， 材料科学与工程， 2020， 硕士

【摘要】 水凝胶是一种内部含有大量水的三维网络结构材料,本征的力学柔性、功能可设计性以及许多类似于生物有机体的独特性质,使得其在组织工程、智能物联网、柔性机器人等领域日益发挥着重要的作用。但是传统的水凝胶强度较低、功能性单一,并且水凝胶的形成过程需要复杂的工艺技术,这些缺点在很大程度上制约了水凝胶的发展和应用。因此,制备简单、性能可调及功能化的水凝胶体系一直是材料科学领域的研究热点之一。本论文利用一种天然小分子——植酸(PA),以及常见凝胶聚合物——聚乙烯醇(PVA)为主要原料制备了三种具有不同结构与功能的水凝胶材料。植酸分子上具有大量磷酸基团,既可作为氢键作用的给受体,又可以成为金属离子的多齿配体,还能为植酸的功能化修饰提供结合位点。通过简单的“一步法”将植酸和聚乙烯醇物理共混,利用植酸(P-OH)与聚乙烯醇(C-OH)之间强的氢键作用制备出了一种可在冰浴条件下实现快速凝胶化的导电水凝胶材料(PVA-PA gel),并探究了植酸添加量对水凝胶强度、透明度、及离子导电性的影响。由于PVA-PA gel的高弹性和高导电性,可将其组装成可穿戴传感器用来监测人体行为和健康状态,并且这种温和的凝胶化条件可进一步将PVA-PA gel应用于可书写柔性电路的制备领域。通过分子层面的设计,构筑了一种含有大量可逆动态氢键和配位键的互穿网络水凝胶(PPFe gel)。首先利用酯化反应将植酸分子接枝到聚乙烯醇分子链上制备出聚乙烯醇植酸酯(PPVA),然后利用铁离子和植酸基团间的配位作用制备出预凝胶,与此同时,凝胶网络中均匀分布的吡咯单体在铁离子的氧化作用下发生原位聚合,最终得到了一种类“橡皮泥态”的导电水凝胶。这种水凝胶具有优异的自修复性、可塑性和光热转换能力,在温度传感、光热诊疗等领域有着潜在应用。利用植酸钠(P=O)与聚乙烯醇(C-OH)之间的氢键作用得到了聚乙烯醇-植酸钠复合物,将这种复合物经过压制成型和浸泡过程可获得一种高强度、抗溶胀的导电水凝胶(PVA-PANa gel)。这种高密度的水凝胶网络结构赋予了该水凝胶材料接近人体软骨组织的高强度和高弹性,同时克服了传统水凝胶易吸水溶胀的缺点。由于植酸钠和聚乙烯醇均具有较好的生物相容性,此类PVA-PANa gel有望成为生物医学领域仿生软骨、仿生组织等的理想替代材料。更多还原

【Abstract】 Hydrogel is a three-dimensional network structure containing a large amount of water inside.The intrinsic mechanical softness,functional designability,and many unique properties similar to biological organisms make it an increasingly important role in the fields of tissue engineering,intelligent Internet of things and flexible robots.However,traditional hydrogels have low strength,are prone to permanent fracture,and the polymerization process of hydrogels depends on external conditions.These shortcomings have largely restricted the development and application of hydrogels.Therefore,the development of a hydrogel system with simple preparation and adjustable performance is an urgent problem for engineering.In this thesis,three kinds of hydrogel with different structures and functions were prepared by using a natural product-phytic acid(PA)and polyvinyl alcohol(PVA)as the main raw materials.Phytic acid has a large number of phosphate groups,which can be used as hydrogen bonding acceptors and coordination multidentate ligands.The abundant hydroxyl groups on the polyvinyl alcohol molecular chain provide coordinating sites for hydrogen bonding and functional modification.A simple "one-step method" was used to physically blend phytic acid and polyvinyl alcohol,and the hydrogen bonding between phytic acid(P-OH)and polyvinyl alcohol(C-OH)was used to prepare the conductivehydrogel(PVA-PA gel),which can be gelled under ice bath conditions.The effects of the amount of phytic acid for the strength,transparency,and ionic conductivity of hydrogels were also discussed.Due to the high elasticity and high conductivity of PVA-PA gel,it could be assembled into a wearable sensor to monitor human behaviors and health conditions,and this mild gelation condition could be further used for writing flexible circuits.An interpenetrating network hydrogel(PPFe gel)containing a large number of dynamic reversible hydrogen bonds and coordination bonds through a molecular-level design.Polyvinyl alcohol phytate(PPVA)was prepared by grafting phytic acid molecules onto polyvinyl alcohol molecular chains by the esterification reaction,and then a pre-gel was prepared by coordinate bonding between iron ions and phytic acid groups.At the same time,the uniformly distributed pyrrole monomer in the gel network was undergoing in-situ polymerization under the oxidation of iron ions,and finally a "silly putty-like" conductive hydrogel was obtained.Due to the excellent self-healing properties,plasticity,and photothermal conversion ability,this hydrogel has the potential applications in temperature sensing,photothermal treatment,etc.The hydrogen bonding between sodium phytate(P=O)and polyvinyl alcohol(C-OH)to obtain a polyvinyl alcohol-sodium phytate complex.A high strength,anti-swelling conductive hydrogel(PVA-PANa gel)was obtained by molding and soaking processes.This high-density hydrogel network structure gave the hydrogel high strength and elasticity which was close to human cartilage tissue.Moreover,this hydrogel also could overcome the shortcomings of traditional hydrogels,like the easy absorption and swelling in water.Because both sodium phytate and polyvinyl alcohol have good biocompatibility,PVA-PANa gel will become an ideal substitutive material for biomimetic cartilage and biomimetic issue.更多还原