天然高分子材料水凝胶的制备及其应用进展

水凝胶是一种由高分子聚合物构成的三维网络材料,用自然界中天然存在的高聚物及其衍生物材料构建水凝胶,具有生物相容性、环境敏感性高、生物可降解性和对环境无污染等优势。本文介绍了近几年天然高分子水凝胶材料在医药卫生、食品、农业和环保等领域的应用情况;并按材料来源的不同,分类综述了蛋白质、多肽类水凝胶,海藻多糖水凝胶,动物多糖水凝胶,植物多糖水凝胶,其改性和制备复合水凝胶的最新技术、功能特性以及应用领域;最后对天然高分子水凝胶制备的改进方向和重点应用领域进行了展望。     

分子凝胶:从结构调控到功能应用

作为一类典型软物质材料,近年来分子凝胶在生物医学、柔性电子设备、晶体控制生长、水体净化,以及3D打印材料、微纳米材料和高能量密度材料制备等领域表现出巨大的应用潜力,受到人们越来越多的关注。如何提高分子凝胶结构调控效率,拓展分子凝胶功能,促进分子凝胶实际应用已经成为新阶段分子凝胶研究的主要内容。本文结合本课题组的研究工作,从动态共价键调控分子凝胶力学性能、分子凝胶促进高品质有机晶体制备和高性能多孔高分子材料的分子凝胶(凝胶乳液)软膜板制备三个方面阐述分子凝胶的结构调控和功能化应用研究。在此基础上,简要展望分子凝胶研究的发展趋势。     

双网络凝胶吸附剂的构建及其去除水中污染物的应用

近年来,随着工业的迅速发展,水污染危机是世界面临的主要威胁之一,开发新型环境功能材料和技术,实现水体污染物的高效去除是目前研究热点。双网络水凝胶(Double Network hydrogels)是具有三维网络结构的高分子聚合物,其机械性能优越,具备较高的强度,可以承受高水平的拉伸和压缩变形。低溶胀率使水凝胶可以容纳大量水并保持稳定的形态和网络结构。此外,由于其独特的交联方式,它还具有快速的自修复性能和显著的抗疲劳性能。具备众多优点的双网络水凝胶是一种有着巨大潜力的吸附材料,在水处理领域引起广泛关注。本文综述了双网络凝胶吸附剂的物化特性及其分类,以及近年来双网络凝胶吸附剂去除水体中重金属、抗生素和染料等污染物的应用进展。通过该综述,为双网络凝胶吸附剂的深入开发以及在水质净化中的工程应用提供新思路、新方法和新技术。     

磁场敏感性水凝胶研究进展

磁场敏感性水凝胶是一类由聚合物三维网络和磁性组分所构成的复合凝胶,其在药物控制释放、人工肌肉、酶的固定与蛋白质分离等领域具有良好的应用前景。本文综述了磁场敏感性水凝胶的制备方法及其在上述领域的应用。     

水凝胶功能改性研究与应用进展

水凝胶是一种三维网状亲水性高分子软材料,具有良好的固体力学和液体热力学性能,其自身柔软、可塑性强、生物相容性好,具有可降解性和刺激性响应特征。但传统方法制备的水凝胶有诸多缺陷,如有毒性、生物活性低、机械性能差等,使得其应用受限。本文综述了近10年来功能水凝胶制备与改性的主要研究进展及其应用现状,以多吸收位点和高机械强度等性能为主,重点阐述了国内外功能性水凝胶的最新制备方法,包括物理改性中的低分子复合材料交联与构建多重网络和化学改性中的接枝共聚等。详细介绍了该类功能材料在医药、生物、农业和食品等方面的应用现状与发展前景,特别关注了高效短时对外界环境微小变化具有响性的智能印迹水凝胶及其在检测领域的应用,为水凝胶的进一步开发和推广应用提供参考。     

基于多肽结构的聚合物水凝胶

多肽由于具有良好的生物相容性和生物可降解性、生物活性以及自组装特性, 近年来受到了广泛的关注。将多肽自组装特性引入到聚合物中,可赋予聚合物形成凝胶性并对凝胶网络分子结构做出一定控制,进而使凝胶具有如环境响应、力学可调等结构控制性能;将特殊功能性多肽引入到化学交联的聚合物凝胶网络中,可赋予水凝胶生物功能性,如细胞黏附、酶降解、抗菌等;将多肽的凝胶网络构建、结构控制作用以及功能性同时引入获得的物理/化学双重交联凝胶不仅赋予水凝胶一定的功能性,且多肽自组装贡献的物理交联结构还能对化学交联凝胶网络起增强作用。本文综述了基于多肽自组装的物理交联聚合物水凝胶、多肽功能化的化学交联聚合物水凝胶以及基于多肽的物理/化学双重交联的聚合物水凝胶,并展望了这些水凝胶的发展前景。     

自愈性聚合物水凝胶的最新研究进展

主要阐述自愈性聚合物水凝胶的最新研究进展,针对自愈性聚合物水凝胶的愈合机理、不同类型聚合物对水凝胶的自愈性贡献、水凝胶的愈合程度及其验证方法等方面进行了分析和对比。总体而言,无论是在自愈性聚合物的分子设计,还是在其水凝胶的愈合机理研究方面,都取得了重要进展。然而,聚合物水凝胶的自愈合能力还有待进一步提高。新型聚合物设计、水凝胶制备方法的改进和自愈合效率的提高都会对自愈性聚合物水凝胶的进一步应用产生重要影响。     

离子特异性效应调控的功能水凝胶

离子特异性效应又称Hofmeister效应,是指不同离子对生物大分子或聚合物分子的溶解能力产生不同影响的现象,这对指导开发多功能聚合物材料具有重要意义。本文主要以离子与水之间、离子与大分子溶质之间的相互作用为出发点介绍了离子特异性效应的基本产生机制,介绍了离子特异性效应调控水凝胶力学、抗冻、刺激响应性等性能的研究进展,分析了离子对水凝胶性能进行调控的原理,总结了离子特异性效应在水凝胶实际应用中发挥的作用。本文将为功能水凝胶的设计和制备提供指导。     

温敏性抗菌水凝胶的制备与控释技术研究进展

温敏水凝胶是一类通过感知温度变化使自身发生相变的智能型聚合物凝胶,通过负载抗菌剂或抗菌性单体制备抗菌水凝胶是近年来药物控制释放、组织工程以及生物免疫等领域关注的热点。本文概述了负载抗菌剂型温敏性抗菌水凝胶的物理交联和化学交联制备技术的研究概况,着重阐述了温敏性抗菌水凝胶的孔径调控、制备材料调控、载药模式调控等技术的研究进展,并对温敏性抗菌水凝胶的控释技术应用前景,特别是在生物质材料领域的应用前景进行了展望。     

聚乙二醇基智能水凝胶的研究进展

聚乙二醇是一种常见的水溶性高分子,其水凝胶低毒,生物相容性好,广泛应用于生物医学和药学材料;PEG分子链的末端为活泼性基团—羟基,很容易发生化学反应得到聚乙二醇功能单体,利用这种大分子单体很容易制备出结构和性能各异的水凝胶;而且其分子量的应用范围很宽(从几百到几万)。因此利用PEG为基体制备水凝胶具有独特的优势。此外,聚乙二醇基水凝胶以其众多的刺激响应功能显示出了广阔的应用前景,引起了人们的广泛关注。本文综述了近年来聚乙二醇基水凝胶研究方面的进展,包括水凝胶的合成、结构与性能的关系等,并特别强调了点击化学与超分子化学在水凝胶的设计与合成方面的重要性。     

Dual cross-linked networks hydrogels with unique swelling behavior and high mechanical strength: based on silica nanoparticle and hydrophobic association

A series of physically cross-linked hydrogels composed poly(acrylic acid) and octylphenol polyoxyethylene acrylate with high mechanical strength are reported here with dual cross-linked networks that formed by silica nanoparticles (SNs) and hydrophobic association micro-domains (HAMDs). Acrylic acid (AA) and octylphenol polyoxyethylene acrylate with 10 ethoxyl units (OP-10-AC) as basic monomers in situ graft from the SNs surface to build poly(acrylic acid) hydrophilic backbone chains with randomly distributed OP-10-AC hydrophobic side chains. The entanglements among grafted backbone polymer chains and hydrophobic branch architecture lead to the SNs and HAMDs play the role of physical cross-links for the hydrogels network structure. The rheological behavior and polymer concentration for gelation process are measured to examine the critical gelation conditions. The correlation of the polymer dual cross-linked networks with hydrogels swelling behavior, gel-to-sol phase transition, and mechanical strength are addressed, and the results imply that the unique dual cross-linking networks contribute the hydrogels distinctive swelling behavior and excellent tensile strength. The effects of SNs content, molecular weight of polymer backbone, and temperature on hydrogels properties are studied, and the results indicate that the physical hydrogel network integrity is depended on the SNs and HAMDs concentration.     

通过麦克加成反应形成的三臂聚乙二醇丙烯酸酯可注射水凝胶的制备与表征

通过麦克加成反应在磷酸盐缓冲溶液中制备出一种基于三臂聚乙二醇丙烯酸酯的能快速固化的可注射水凝胶.采用倒置法测定了体系的凝胶化时间.通过红外,DMA,溶胀,降解等一系列测试,研究了该水凝胶的结构和物理化学性能.观察到通过控制前体溶液的浓度,可以控制凝胶的成胶时间和所形成凝胶的溶涨率.同时表明该水凝胶具备可注射性和可降解性.细胞毒性评价显示,该水凝胶浸提液无毒性,符合生物材料的安全评价标准.由于麦克加成反应可在人体生理条件(pH7.4,37℃)下快速进行,并且不需要任何引发剂、催化剂和有机溶剂,因此该反应非常适合应用于生物医用材料领域.     

Investigation of the swelling behavior of hydrogels derived from high-molecular-weight poly(2-ethyl-2-oxazoline)

Thermoresponsive hydrogels are of great importance as smart materials. They are usually composed of cross-linked polymers with a lower critical solution temperature (LCST). Although much is known about networks of poly(N-isopropylacrylamide), all other polymers are somewhat neglected. In this work, the temperature-dependent swelling behavior of differently cross-linked thermoresponsive poly(2-ethyl-2-oxazoline) (PEtOx) hydrogels were investigated with regard to varying parameters of the network composition. It was found that the degrees of swelling of the hydrogels converge for a certain polymer/solvent system at a distinct temperature independent of its degree of cross-linking. Furthermore, this temperature correlates with the LCST of the respective starting PEtOx. Its net chain molecular weight M_c only affects the maximum degree of swelling and thus, the swelling–deswelling rate of the hydrogel. The fundamental structure/property relations found in this study could be useful to predict the behavior of other thermoresponsive hydrogels.     

Gelation and yielding behavior of polymer–nanoparticle hydrogels

Polymer–nanoparticle hydrogels are a unique class of self-assembled, shear-thinning, yield-stress fluids that have demonstrated potential utility in many impactful applications. Here, we present a thorough analysis of the gelation and yielding behavior of these materials with respect to the polymer and nanoparticle component stoichiometry. Through comprehensive rheological and diffusion studies, we reveal insights into the structural dynamics of the polymer nanoparticle network that identify that stoichiometry plays a key role in gelation and yielding, ultimately enabling the development of hydrogel formulations with unique shear-thinning and yield-stress behaviors. Access to these materials opens new doors for interesting applications in a variety of fields including tissue engineering, drug delivery, and controlled solution viscosity.     

氧化石墨烯/聚合物复合水凝胶的研究进展

氧化石墨烯是一种具有单原子厚度的二维材料, 具有优异的力学性能和良好的水分散性, 其表面有大量的含氧官能团. 将氧化石墨烯引入水凝胶体系中可以提高水凝胶的机械性能, 丰富其刺激响应的类型. 目前, 氧化石墨烯水凝胶在高强度、 吸附、 自愈合及智能材料等很多领域均有出色的表现. 氧化石墨烯水凝胶的研究已有10年的历史. 本文总结了氧化石墨烯水凝胶的制备方法, 归纳了智能氧化石墨烯水凝胶在光热响应、 pH响应和自愈合3个方面的响应机理和研究进展, 并综合评述了其在高强度水凝胶、 生物医学、 智能材料和污水处理等方面的应用前景.     

Stimulus-responsive hydrogels made from biosynthetic fibrinogen conjugates for tissue engineering: structural characterization

Nanostructured hydrogels based on "smart" polymer conjugates of poloxamers and protein molecules were developed in order to form stimulus-responsive materials with bioactive properties for 3-D cell culture. Functionalized Pluronic F127 was covalently attached to a fibrinopeptide backbone and cross-linked into a structurally versatile and mechanically stable polymer network endowed with bioactivity and temperature-responsive structural features. Small angle X-ray scattering and transmission electron microscopy combined with rheology were used to characterize the structural and mechanical features of this biosynthetic conjugate, both in solution and in hydrogel form. The temperature at which the chemical cross-linking of F127-fibrinopeptide conjugates was initiated had a profound influence on the mechanical properties of the thermo-responsive hydrogel. The analysis of the scattering data revealed modification in the structure of the protein backbone resulting from increases in ambient temperature, whereas the structure of the polymer was not affected by ambient temperature. The hydrogel cross-linking temperature also had a major influence on the modulus of the hydrogel, which was rationally correlated to the molecular structure of the polymer network. The hydrogel structure exhibited a small mesh size when cross-linked at low temperatures and a larger mesh size when cross-linked at higher temperatures. The mesh size was nicely correlated to the mechanical properties of the hydrogels at the respective cross-linking temperatures. The schematic charts that model this material's behavior help to illustrate the relationship that exists between the molecular structure, the cross-linking temperature, and the temperature-responsive features for this class of protein-polymer conjugates. The precise control over structural and mechanical properties that can be achieved with this bioactive hydrogel material is essential in designing a tissue-engineering scaffold for clinical applications.     

Morphology of Photopolymerized End-linked Poly(ethylene glycol) Hydrogels by Small Angle X-ray Scattering

Due to the biocompatibility of poly(ethylene glycol) (PEG), PEG-based hydrogels have attracted considerable interest for use as biomaterials in tissue engineering applications. In this work, we show that PEG-based hydrogels prepared by photopolymerization of PEG macromonomers functionalized with either acrylate or acrylamide end-groups generate networks with crosslink junctions of high functionality. Although the crosslink functionality is not well controlled, the resultant networks are sufficiently well ordered to generate a distinct correlation peak in the small angle x-ray scattering (SAXS) related to the distance between crosslink junctions within the PEG network. The crosslink spacing is a useful probe of the PEG chain conformation within the hydrogel and ranges from approximately 6 to 16 nm, dependent upon both the volume fraction of polymer and the molecular weight of the PEG macromonomers. The presence of a peak in the scattering of photopolymerized PEG networks is also correlated with an enhanced compressive modulus in comparison to PEG networks reported in the literature with much lower crosslink functionality that exhibit no scattering peak. This comparison demonstrates that the method used to link together PEG macromonomers has a critical impact on both the nanoscale structure and the macroscopic properties of the resultant hydrogel network.     

Computational approaches for understanding and predicting the self-assembled peptide hydrogels

Self-assembled peptide hydrogel is a promising biomaterial and has been widely applied in many fields. As a typical self-assembly material, peptide hydrogel exhibits properties different from traditional polymer hydrogel, and has unique features in molecular design, structural elements of hydrogel, and control strategies. With the desire to apply the principles of self-assembly to the design and prediction of peptide hydrogels, there has more and more emphasis on understanding the driving forces and microscopic behaviors involved in the self-assembly process. Computational methods have played an increasingly important role in recent research in helping to reveal the relationship between molecular chemical structure and self-assembly processes as well as assembled morphologies, thus determining the ability of supramolecular gelation. This review aims to summarize the application of computational tools to obtain a better fundamental understanding of the multi-scale structural details of self-assembled peptide hydrogels and to predict the gelation behavior of supramolecular nanofibers. It is expected that researchers will consider using these computational tools when investigating and designing novel peptide hydrogel materials.     

Co‐assembly of Polyoxometalates and Zwitterionic Amphiphiles into Supramolecular Hydrogels: From Crystalline Fibrillar to Amorphous Micellar Networks

Gelation mechanism is of utmost importance to the rational design of supramolecular hydrogelators. Although both kinetic and thermodynamic controlled self‐assembly processes have been widely studied in hydrogels, the formation relationship between crystalline and amorphous gel networks still remains ambiguous. Herein, a gelation transformation from a kinetic to a thermodynamic process was achieved by balancing the rigidity and flexibility of the inorganic–organic co‐assemblies. By using polyoxometalates and zwitterionic amphiphiles, the transition morphologies between crystalline and amorphous hydrogel networks were evidenced for the first time, as ordered wormlike micelles. Given the versatile applications of hydrogels in biological systems and materials science, these findings may highlight the potential of inorganic–organic binary supramolecular hydrogelators and fill in the blank between kinetic and thermodynamic controlled gelation processes.     

Interpenetrating Network Hydrogels based on Nanostructured Conductive Polymers for Flexible Supercapacitor

Flexible conductive polymer hydrogels are unique material that synergize the features of conductive polymers and hydrogels. They are excellent candidates for the flexible supercapacitor electrodes. In this paper, flexible conductive polymer hydrogels were prepared with poly(vinyl alcohol) as soft skeleton through cyclic freezing-thawing method. Firstly, phytic acid-doped polyaniline with crosslinked network was prepared using phytic acid as the dopant and crosslinking agents. Hydrogels with interpenetrating binary network nanostructure were then formed by freezing-thawing method. The interpenetrating binary network structure endowed the hydrogel reliable mechanical properties with decent flexibility and compressive strength of 3.64 MPa. More importantly, this unique structure enable them to maintain highly specific capacitance (314 F/g at the current density of 0.5 A/g).