聚乙烯醇/壳聚糖复合水凝胶的物理化学性质

测定了聚乙烯醇(PVA)和壳聚糖(CS)复合水凝胶的平衡含水量、熔融焓、等温溶胀动力学和非等温失水动力学等性质,讨论了水凝胶的组成和制备参数对这些性质的影响.结果显示:PVA/CS复合水凝胶具有适宜于软骨修复替代材料的网络结构和平衡含水量.CS与PVA复合减弱了凝胶的结晶度,但却增强了水与凝胶支架的相互作用.尽管水凝胶力学拉伸强度有所降低,但却优化了凝胶的生物相容性和降解能力.PVA/CS复合水凝胶是一种潜在的软骨修复材料,作为一种理论研究的模型体系,它将促进热力学在复杂医用材料方面的应用.     

不同结晶度聚乙烯醇水凝胶中水氢键缺损的拉曼光谱学研究

聚乙烯醇 (ＰＶＡ)是一种水溶性高分子 ,它在一定条件下可以部分结晶形成水凝胶 ,其结晶度必然影响其机械性能及水在水凝胶中的状态 .部分结晶交联所得的ＰＶＡ水凝胶 ,由于无毒、机械性能好常用来作为生物医用材料 ,如接触眼镜、人工关节润滑软骨等[1,2 ] .水凝胶是轻度交联的高分子网络 ,其内含有大量的水 ,高分子交联网络与水之间的相互作用决定着水凝胶的物理性质和化学性质[3 ,4 ] .一般认为 ,水凝胶中的水以三种状态存在 ,即键合水 (Ｂｏｕｎｄｗａｔｅｒ)、自由水 (Ｆｒｅｅｗａｔｅｒ)和间隙水 (Ｉｎｔｅｒｓｔｉｔｉａｌｗａｔｅｒ…     

物理交联聚乙烯醇/羟基末端聚酰胺-胺树型高分子水凝胶的制备与性质研究

聚乙烯醇(PVA)是一种水溶性的生物相容性好并可降解的合成高分子,PVA通过化学或物理方法交联可以形成水凝胶,PVA与聚丙烯酸(PAA)、聚N-异丙基丙烯酰胺(PNIPA)、聚乙烯基吡咯烷酮(PVP)及壳聚糖形成互穿网络型水凝胶,改善凝胶的性质,另一方面,树型高分子是一     

与基板间相互作用对聚乙烯醇水凝胶摩擦行为的影响

选择分别与聚乙烯醇(PVA)水凝胶具有较强和较弱相互作用的基板, 研究水介质中PVA水凝胶在其表面的摩擦行为. 结果表明, 与具有弱相互作用的凝胶-玻璃板体系相比, 具有强相互作用的凝胶-铝板体系的摩擦力(f)较高, 且其粘弹-流体润滑转变速率(vf)较大, 用吸附-排斥模型对其进行了分析. 当滑动速率v相似文献   

温度敏感聚(N-异丙基丙烯酰胺)/聚(乙烯醇)水凝胶的制备及性能研究

聚 (N -异丙基丙烯酰胺 ) (PNIPA)水凝胶具有温度敏感性 ,其在 33℃左右有一个相转变温度或较低临界溶解温度 (L CST) [1,2 ] .当外界温度低于 LCST时 ,PNIPA水凝胶吸水溶胀 ;而当外界温度高于L CST时 ,PNIPA水凝胶剧烈收缩失水 ,发生相分离 .这种相分离特性应用于药物的控制释放 [3] .固定化酶[4 ] 和循环吸收剂 [5] 等领域 .然而 ,通常的 PNIPA水凝胶是通过化学键交联而成的三维网络聚合物 ,很难发生解体或进行生物降解 ,其在某些特定场合 (如药物的体内释放等 )受到一定限制 .聚乙烯醇 (PVA)的亲水性和生物相容性较好 ,是…     

聚合物纳米粒子的制备及其新型物理水凝胶结构的AFM和SEM研究

凝胶材料是生物系统的重要组成物质,在生物模拟、仿生等方面具有重大意义.最近凝胶方面的研究日益受到关注^[1,2],高分子凝胶体系的研究也得到深入开展^[3,4].在智能水凝胶、凝胶特性基础研究和医用凝胶材料等领域已取得了较大进展.     

冷冻/解冻制备的聚乙烯醇水凝胶的结构和流变性研究

研究了冷冻/解冻法制备的不同浓度(5wt%～25wt%)聚乙烯醇(PVA)水凝胶的结构和流变行为之间的关系.由XRD确定了凝胶中PVA的结晶度和晶粒尺寸.用应力流变仪研究了凝胶的流变行为,包括动态模量和蠕变等.在频率为1Hz和低应力的条件下,测量了凝胶的储能模量和损耗模量.在该试验条件下,PVA水凝胶的形变是完全可以回复的.低频率区和低应变区的储能模量随浓度增加而变大,但当浓度超过20wt%时,储能模量增加速率明显降低.由PVA水凝胶在1Hz时的储能模量和结晶度的数据,理论分析得到了形成PVA水凝胶的最低PVA浓度和最小结晶度.当PVA浓度低于15wt%时,储能模量主要由PVA的微晶控制,分子链间的氢键影响很小.通过低应变区储能模量的数值计算出了凝胶网孔尺寸的结构参数.同时对不同温度下PVA水凝胶的储能模量数据进行了标度分析.PVA水凝胶的蠕变行为显示,随浓度提高,凝胶的蠕变黏弹性由线性向非线性转变.     

低分子物质在聚乙烯醇水凝胶中的扩散

水凝胶是指一种网络结构中含大量水,而不溶于水的高分子材料。近年来,发现聚乙烯醇(PVA)水溶液在低温冷冻一段时间,可形成强度较高的水凝胶弹性体,用这种水凝胶制得的固定化增殖细胞凝胶,在生物工程材料开发中取得了很好的效果。本文旨在研究低分子物质在PVA水凝胶中的扩散性能。     

制备参数对聚乙烯醇水凝胶-玻璃基板摩擦行为的影响

采用不同方法制备了聚乙烯醇(PVA)水凝胶,研究了制备参数对水凝胶/玻璃摩擦体系的影响.结果表明,混合溶剂有利于凝胶均匀网络的形成,制备的凝胶强度较高;冷冻解冻次数的增加有利于PVA水凝胶强度的提高;超高相对分子质量聚氧化乙烯(PEO)的加入,可使PVA形成更为致密、均匀的网络,显著提高PVA水凝胶的模量(E).低滑动速率(v)时,高E的水凝胶具有较高的摩擦力(f),但易在较低v下形成流体动力润滑,使其在较高v(10-1~100m/s)时反而呈现出较低的摩擦力,该速率范围与人体正常行走时膝关节软骨的运动速率相当.PEO的加入可降低较高v时的f,而低v区f的降低与加入的PEO浓度有关.     

PVA-PAMPS-PAA三元互穿网络型水凝胶的合成及其性能研究

以2-丙烯酰胺基-2-甲基丙磺酸(AMPS)、丙烯酸(AA)以及聚乙烯醇(PVA)为原料,制备了PVA-PAMPS-PAA三元互穿网络型(T-IPN)水凝胶.红外分析表明,PVA与PAA以及PAMPS之间形成了较强的氢键,使得PVA分子上的C—O伸缩震动吸收峰移向了低波数处.X射线衍射以及电镜分析表明,当PVA用量较低时,PVA能均匀的穿插于凝胶网络中,形成完善的互穿网络结构,当PVA用量过高时,部分的PVA结晶而使得凝胶出现相分离.研究了该三元互穿网络型水凝胶的溶胀性能,结果表明,该水凝胶的平衡溶胀比在200至340之间,并且随着AA以及AMPS用量的增加,凝胶的溶胀速率以及平衡溶胀比均升高.该三元互穿网络型水凝胶在酸性溶液中和在碱性溶液中表现出截然不同的消溶胀性能;并且随着溶液pH的升高,凝胶在pH=9.0附近出现体积突变,表现出pH敏感性.通过研究T-IPN水凝胶的抗压缩性能发现,利用线型高分子、柔性高分子网络以及刚性高分子网络制备的三元互穿网络型水凝胶能在高溶胀比下保持较高的强度.溶胀比为180的T-IPN水凝胶,其最大抗压缩强度可达12.1 MPa.进一步研究发现,凝胶的组成以及溶胀比均对凝胶的抗压缩强度和压缩应变均存在较大的影响.     

会变形的水凝胶

本实验是关于可变形水凝胶的制备及其复杂形变的设计和调控的新创综合实验。首先,利用自由基聚合交联法制备含有聚丙烯酸钠(PNaAAc)的聚乙烯基吡咯烷酮-聚丙烯酰胺(PVP-PAAm)水凝胶。该凝胶具有优良的力学性能,其中PNaAAc可与Fe3+等金属离子络合,从而增加水凝胶的交联密度,降低其溶胀程度。使用离子转移印花技术和新开发的离子墨水打印技术在凝胶单面或双面不同位置引入Fe3+交联,改变水凝胶局部表面的交联密度和溶胀性能。处理后的凝胶样品在溶胀或去溶胀时可发生由一维到二维、二维到三维以及简单三维到复杂三维的复杂可控形变。     

智能性水凝胶

“智能”材料具有传感、处理和执行功能，水凝胶作为智能材料其应用前景良好。本文综述了智能水凝胶的近期研究发展，以Ｆｌｏｒｙ的溶胀理论着重探讨了刺激响应性，并介绍了化学机械现象及凝胶相转变。     

环糊精超分子水凝胶*

本文综述了近年来基于环糊精包合作用的超分子水凝胶的研究进展,主要包括：环糊精与线性、星型、接枝、超支化聚合物包合形成的多聚(准)轮烷自组装制备超分子物理凝胶及功能化多聚(准)轮烷经交联反应制备超分子化学凝胶;环糊精、环糊精二聚体及其水溶性聚合物与带疏水性侧基的聚合物经“锁-钥匙”包合作用形成超分子物理凝胶;及其在药物、基因释放载体与组织工程支架中的应用。着重介绍了剪切、温度、pH值、光等刺激-响应性超分子水凝胶的设计与制备。     

无机纳米复合水凝胶*

近年来,纳米材料由于具有诸多奇特效应而备受关注。将无机纳米粒子与高分子水凝胶复合,可以很大程度地改善传统水凝胶的使用性能,因而成为近年来水凝胶研究领域的热点课题之一。纳米材料的形貌多姿多彩,相同材质不同形貌的纳米材料对复合材料性能有着不同的作用。本文从不同形貌（层状、管状及球状等）的无机纳米材料对复合水凝胶性能影响出发,以无机纳米粒子的形貌分类,综述了当前无机纳米复合水凝胶的研究进展。     

Antibacterial Hybrid Hydrogels

Bacterial infectious diseases and bacterial‐infected environments have been threatening the health of human beings all over the world. In view of the increased bacteria resistance caused by overuse or improper use of antibiotics, antibacterial biomaterials are developed as the substitutes for antibiotics in some cases. Among them, antibacterial hydrogels are attracting more and more attention due to easy preparation process and diversity of structures by changing their chemical cross‐linkers via covalent bonds or noncovalent physical interactions, which can endow them with various specific functions such as high toughness and stretchability, injectability, self‐healing, tissue adhesiveness and rapid hemostasis, easy loading and controlled drug release, superior biocompatibility and antioxidation as well as good conductivity. In this review, the recent progress of antibacterial hydrogel including the fabrication methodologies, interior structures, performances, antibacterial mechanisms, and applications of various antibacterial hydrogels is summarized. According to the bacteria‐killing modes of hydrogels, several representative hydrogels such as silver nanoparticles‐based hydrogel, photoresponsive hydrogel including photothermal and photocatalytic, self‐bacteria‐killing hydrogel such as inherent antibacterial peptides and cationic polymers, and antibiotics‐loading hydrogel are focused on. Furthermore, current challenges of antibacterial hydrogels are discussed and future perspectives in this field are also proposed.     

有机-无机纳米复合水凝胶*

本文综述了近年来有机-无机纳米复合水凝胶领域的研究进展。针对无机成分的不同种类及复合形式,本文将目前已见报道的有机-无机纳米复合水凝胶划分为三类,分别为层状硅酸盐纳米插层复合水凝胶、粘土交联纳米复合水凝胶和二氧化硅纳米杂化复合水凝胶。阐述了三类纳米复合水凝胶的发展趋势,特别就它们的合成方法进行了详细归纳与总结。在此基础上,介绍了纳米无机成分对复合水凝胶的性能增强机理,并就三者之间的增强差异进行了说明。     

电场敏感的智能性水凝胶*

电场敏感水凝胶是一类在电刺激下可以溶胀、收缩或弯曲的智能性水凝胶,其主要特点是可以将电能转化为机械能。本文对近年来已见报道的电场敏感水凝胶的研究进行了较为详细的综述。同时,对电场敏感水凝胶的响应机理、影响水凝胶响应性的因素以及其在能量转换装置、人工肌肉等方面的应用也作了相应的介绍。     

Injectable Biodegradable Hydrogels

Injectable biodegradable copolymer hydrogels, which exhibit a sol–gel phase transition in response to external stimuli, such as temperature changes or both pH and temperature (pH/temperature) alterations, have found a number of uses in biomedical and pharmaceutical applications, such as drug delivery, cell growth, and tissue engineering. These hydrogels can be used in simple pharmaceutical formulations that can be prepared by mixing the hydrogel with drugs, proteins, or cells. Such formulations are administered in a straightforward manner, through site‐specific control of release behavior, and the hydrogels are compatible with biological systems. This review will provide a summary of recent progress in biodegradable temperature‐sensitive polymers including polyesters, polyphosphazenes, polypeptides, and chitosan, and pH/temperature‐sensitive polymers such as sulfamethazine‐, poly(β‐amino ester)‐, poly(amino urethane)‐, and poly(amidoamine)‐based polymers. The advantages of pH/temperature‐sensitive polymers over simple temperature‐sensitive polymers are also discussed. A perspective on the future of injectable biodegradable hydrogels is offered.

     

Environment-Responsive Polymeric Hydrogels

Some polymers may respond by changing their physico-chemical perperties when the environmental conditions such as pH, temperature and ionic strength are varied. For example,thermosensentive polymers can exhibit a sharp change in solubility in a solvent such as water at a certain temperature known as the lower critical solution temperature (LCST). The responsiveness of the polymeric materials has important technological implications since they can be employed for various applications. The responsiveness of such polymers can be varied by means of copolymerization, chemical modification of the polymer, or the addition of reagents into the solutions. It is interesting and important to tune predictably the responsiveness of the polymers for the different applications. The sensitivity towards the external environment can be modulated by the relative hydrophilicity of the copolymers, hence the chemical structure and composition of the comonomers used.     

Hydrogels from diacylphosphatidylcholine

The formation of hydrogels from diacylphosphatidylcholine (PC) and water/glycerol mixtures and the properties of the gels are reported. The gels are formed when L_α phases from the PC in the solvent mixtures are cooled from T >55 °C below the Krafft temperature of the PC (T _m ∼52 °C). The glycerol can also be replaced by other co-solvents like butylenglycol. Above T _m, the PC spontaneously forms L_α phases with multilamellar vesicles that show a strong stationary birefringence. On cooling below T_m, the L_α phases jellify to transparent gels. DSC measurements of the gels show that the PC molecules undergo a phase transition into the crystalline state. This transition does not seem to be accompanied by a change of the morphological structure of the liquid L_α phase. The hydrogels also have a stationary birefringence. The vesicles in the gels have been imaged by the CryoTEM method. The hydrogels are already formed with as little as 1% of PC in the mixed solvent. The rheological properties of the gels were determined from oscillating rheological measurements. Samples with 10% of PC have a storage modulus of >10,000 Pa.