瓜尔胶衍生物水凝胶在表面活性剂中的溶胀性能研究

以可生物降解的改性多糖羧甲基羟丙基瓜尔胶、敏感功能性单体丙烯酸为主要原料、在性能增强剂粘土存在下,合成一类具有pH敏感性质的新型杂化水凝胶,同时探索所得杂化水凝胶在表面活性剂中的溶胀行为。结果表明,凝胶的溶胀比随着阳离子表面活性剂浓度的增大而降低;随着阴离子表面活性剂浓度的增大而增大。     

pH敏感高分子水凝胶的合成及性能研究

从分子设计的角度出发,选用具有优良pH敏感的丙烯酸(AAc)为基本原料,制备了pH敏感水凝胶,系统研究了水凝胶的基本物理性能(密度、平均分子量、交联密度、平衡态水含量、固定电荷密度等),测试了水凝胶在不同离子强度下的溶胀、退溶胀性能,并对其响应机理进行了探讨,同时对水凝胶的机械性能进行测试.结果表明:pH敏感水凝胶的机械性能随着pH值增大而变化,其变化幅度最大可达到80%;其机械性能强烈依赖于平衡态溶胀率;离子强度的大小也对水凝胶的机械性能有着决定性影响.     

温度及pH敏感性互穿网络水凝胶的制备研究

采用分步法制备了聚丙烯酸/N-异丙基丙烯酰胺互穿网络水凝胶,研究了互穿网络水凝胶的溶胀性能。结果表明,当水溶液的pH增大时,水凝胶的溶胀率显著增加。在一定的温度范围内,水凝胶的溶胀率随温度升高而减小。聚丙烯酸/N-异丙基丙烯酰胺互穿网络水凝胶表现出显著的温度及pH敏感双重特性。     

一种新型聚天冬氨酸水凝胶的制备及其药物缓释性能研究

介绍了一种新型羟化聚天冬氨酸-乙基纤维素(PASP-EC)互穿网络水凝胶的制备,研究了交联剂用量、乙醇胺用量及乙基纤维素(EC)用量对水凝胶溶胀性能的影响;同时,进行了水凝胶的pH敏感性测试,并以5-Fu为药物模型,研究其在肠液中(pH=7.4)的药物控释性能。实验结果表明,当己二胺、乙醇胺、EC的用量分别是聚琥珀酰亚胺(PSI)用量的3%、20%、30%时,水凝胶的溶胀性能最佳,达到290倍;且随着乙醇胺用量的增加,水凝胶在50%乙醇中的溶胀性能提高。pH敏感实验表明,羟化PASP-EC水凝胶具有pH敏感性。羟化PASP-EC水凝胶对5-Fu具有缓释效果,随着EC用量增加,缓释效果越明显。     

β-环糊精/海藻酸钠水凝胶的制备及性能研究

将海藻酸钠(SA)和β-环糊精(β-CD)共混制备了复合水凝胶,并讨论了交联剂浓度、原料配比对水凝胶溶胀性能的影响。结果表明,当两者的共混比例为1∶2、w(交联剂)为6%、交联时间为1h时,水凝胶的溶胀性能较好。水凝胶在pH=1.2时的溶胀率仅为1.2,而在pH=7.4时的溶胀率达到14.2,具有良好的pH敏感性。以牛血清蛋白(BSA)为模型药物,研究了β-CD/SA水凝胶作为药物载体对BSA的负载及释放性能,结果表明:在模拟胃液中的累计释放量较小(21.5%),且释放速率较慢;在模拟肠液中的累计释放量为70.2%,具有良好的pH敏感控制释放性能。     

聚(异丙基丙烯酰胺-羟甲基丙烯酰胺)/壳聚糖水凝胶的制备及其释药性能

以异丙基丙烯酰胺(NIPAAm)和羟甲基丙烯酰胺(NHMAm)为共聚单体与壳聚糖(CS)制备形成了温度敏感和pH敏感的互穿网络(IPN)水凝胶Poly(NIPAAm-co-NHMAm)/CS;用红外光谱表征了其结构特征,研究了不同条件下水凝胶的溶胀性能,并初步研究了水凝胶对药物双氯芬酸钠(DS)的缓释效果。结果表明,该水凝胶具有明显的温度和pH敏感性,温度越高,溶胀度越小,释药越慢;pH越小,溶胀度越大;CS含量为0.6%时溶胀度最大。在NHMAm单体质量配比为8.7%时,水凝胶的低临界溶液温度(LCST)达到38℃,且此时对DS持续释药时间可达到24 h。水凝胶的释药动力学曲线符合修正的一级动力学模型。该水凝胶体系可通过改变NHMAm单体配比来调节温敏特性,是一种潜在的温度和pH双重敏感的药物缓释载体。     

温度和pH双重刺激响应型水凝胶的溶胀性能研究

以丙烯酰胺、丙烯酸和双丙酮丙烯酰胺为原料,以N,N'-亚甲基双丙烯酰胺为交联剂,2-酮戊二酸为引发剂,采用光引发聚合方法制备出系列新型温度和pH响应型水凝胶。考察了交联剂用量、水凝胶组成、温度和pH值对凝胶溶胀性能的影响。结果表明,随交联剂用量的增加,凝胶的溶胀率减小,随凝胶组成中AA含量的增加,凝胶的溶胀率增加。凝胶的溶胀率随温度的升高而减小,随pH值的增大而增加,表现出显著的温敏和pH敏感性。     

pH敏感性P(AA-g-MPEGMac)水凝胶的制备及其性能研究

通过丙烯酰氯与聚乙二醇单甲醚(MPEG)酰化反应得到聚乙二醇单甲醚甲基丙烯酸酯(MPEGMac),将其与丙烯酸共聚得到MPEG侧链接枝并交联聚丙烯酸的pH敏感水凝胶P(AA-g-MPEGMac),研究了pH、单体配比对凝胶溶胀性能、溶胀动力学和退溶胀动力学的影响。初步探讨了模拟胃液(pH 1.4)和肠液(pH 7.4)中水凝胶对茶碱的控释情况。结果表明,凝胶具备良好的pH敏感性和快速的退溶胀速率等特征;溶胀初期水的扩散趋于non-Fickian模式,水凝胶的溶胀行为满足Schott二级动力学方程;载药凝胶在模拟肠液中对药物的累计释放率明显大于胃液中的累计释放率。     

聚乙烯醇-壳聚糖复合水凝胶的溶胀性能

以聚乙烯醇(PVA)和壳聚糖为原料、以戊二醛为交联剂,在醋酸溶液中合成了聚乙烯醇-壳聚糖复合水凝胶,研究了影响水凝胶溶胀性能的多种因素,实验结果表明,该凝胶对pH、离子、温度敏感,且在pH=3.13盐酸溶液、常温下的蒸馏水及8℃蒸馏水中溶胀度较大,分别为1 112.2%、974.2%、1 036.8%,凝胶溶胀度随着干燥温度及干燥时间的增加而减小,聚乙烯醇种类对水凝胶溶胀性能有显著影响,PVA-1788与壳聚糖形成的水凝胶溶胀度最大为2 074.1%。聚乙烯醇-壳聚糖复合水凝胶因具有优良的机械强度、生物相容性及生物降解性,同时又具有pH/离子/温度敏感性,因此日益显示其在生物医学材料等领域的重要性。     

丙烯酰胺类共聚物水凝胶的合成及性能研究

用自由基聚合法合成了不同摩尔配比的HEMA／AM共聚物水凝胶材料。研究了单体组成、温度、pH值、离子强度等因素对凝胶溶胀性能的影响。结果表明：水凝胶的溶胀速度较快;水凝胶在pH值小于4及pH值大于9的酸、碱溶液中发生水解,导致水凝胶的饱和含水量大幅增加,而在弱酸性溶液中几乎没有变化;水凝胶的饱和含水量对离子强度的变化不够敏感;随着温度的升高水凝胶的饱和含水量略有减少,说明此类水凝胶对温度的敏感性也较弱。     

Preparation and characterization of sodium alginate/poly(<Emphasis Type="Italic">N</Emphasis>-isopropylacrylamide)/clay semi-IPN magnetic hydrogels

pH- and temperature-responsive semi-interpenetrating magnetic nanocomposite hydrogels (NC hydrogels) were prepared by using linear sodium alginate (SA), poly(N-isopropylacrylamide) (PNIPAM) and Fe₃O₄ nanoparticles with inorganic clay as an effective multifunctional cross-linker. The effects of cross-linker and SA contents on various physical properties were investigated. The NC hydrogels exhibited a volume phase transition temperature (VPTT) around 32 °C with no significant deviation from the conventional chemically cross-linked PNIPAM hydrogels (OR hydrogels). The swelling ratios of NC hydrogels were much larger than those of OR hydrogels. Moreover, the swelling ratios of NC hydrogels gradually decreased with increasing the contents of clay and increased with increasing the contents of SA. The pH sensitivity of NC hydrogels was evident below their VPTT. The NC hydrogels had a much better mechanical property than the OR hydrogels. The results showed that the incorporation of clay did not affect the saturation magnetization of the hydrogels.     

Semi‐IPN carrageenan‐based nanocomposite hydrogels: Synthesis and swelling behavior

Inclusion of nano‐clays into hydrogels is an efficient approach to produce nanocomposite hydrogels. The introduction of nano‐clay into hydrogels causes an increase in water absorbency. In the present work, Nanocomposite hydrogels based on kappa‐carrageenan were synthesized using sodium montmorillonite as nano‐clay. Acrylamide and methylenebisacrylamide were used as monomer and crosslinker, respectively. The structure of nanocomposite hydrogels was investigated by XRD and SEM techniques. Swelling behavior of nanocomposite hydrogels was studied by varying clay and carrageenan contents as well as methylenebisacrylamide concentration. An optimum swelling capacity was achieved at 12% of sodium montmorilonite. The swollen nanocomposite hydrogels were used to study water retention capacity (WRC) under heating. The results revealed an increase in WRC due to inclusion of sodium montmorilonite clay. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

温度及pH敏感共聚/粘土纳米复合水凝胶的合成与性能研究

以无机粘土为交联剂制备了具有温度、pH双重敏感性的聚（N-异丙基丙烯酰胺-co-甲基丙烯酸-β-羟乙酯）/粘土纳米复合水凝胶（P（NIPA-co-HEMA）/clay）,并用红外和X衍射对其结构和形态进行了表征。在弱碱性（pH=7.4）和25℃条件下,分别研究了温度和不同pH缓冲溶液对该凝胶溶胀度的影响,测定了纳米复合水凝胶的力学性能。结果表明：水凝胶的粘土已被剥离成单片层,且均匀分散在凝胶网络中,起交联作用;P（NIPA-co-HEMA）/clay具有良好的温度、pH双重敏感特性;凝胶的断裂伸长率〉1000%。     

聚（N-异丙基丙烯酰胺）／海藻酸钠／粘土复合水凝胶的制备及溶胀动力学研究

以无机粘土为交联剂制备了聚（N-异丙基丙烯酰胺）／海藻酸钠／粘土（PINPA／SA／Clay）复合水凝胶,通过红外光谱、X射线衍射对凝胶的结构进行了表征,结果表明：粘土的结晶结构已被破坏,粘土规整的片层被剥离并在凝胶中无序分布,起到交联剂的作用;随粘土含量的增加,凝胶网络交联密度增加,溶胀速度下降。在不同温度下对不同粘土含量的凝胶进行了溶胀动力学测试,表明在低于其相转变温度时,凝胶的扩散类型为non－Fickian扩散。     

Study on a new polymer/graphene oxide/clay double network hydrogel with improved response rate and mechanical properties

pH‐ and temperature‐responsive double network hydrogels (DN hydrogels) were prepared by using poly (N‐isopropylacrylamide) (PNIPAM) as a tightly crosslinked network (1st network), polyacrylic acid (PAA) as a loosely crosslinked network (2nd network), with clay and graphene oxide as effective crosslinkers and reinforcing fillers. The structure and morphology of the hydrogels were characterized by SEM, FTIR, DSC, and TGA. The synergetic effects of clay, GO and DN structure on various physical properties were investigated. With the increasing of crosslinking densities, the swelling ratios of DN hydrogels gradually decreased by increasing the contents of graphene oxide and PAA. While the DN hydrogels had much better mechanical properties than that of the conventional chemically cross‐linked PNIPAM hydrogels. POLYM. ENG. SCI., 55:1361–1366, 2015. © 2015 Society of Plastics Engineers     

Structure‐property and swelling behavior of electron beam irradiated poly(vinyl alcohol)/acrylamide/sodium montmorillonite clay composites

Composites based on poly(vinyl alcohol) (PVA), acrylamide monomer (AM) and sodium montmorillonite clay (MMT) were prepared, in the form of thin films, by solution casting. The PVA/AM/MMT composites films were then exposed to electron beam irradiation to form crosslinked network structure. The structure‐property behavior of PVA/AM/MMT hybrids was demonstrated by x‐ray diffraction (XRD), scanning electron microscopy, gel content, color intensity, thermogravimetric analysis (TGA) and swelling behavior in aqueous solutions. The results indicated that the introduction of MMT clay ratio up to 5% decreased the gel content of PVA/AM hydrogels. The color measurements indicated that the introduction of MMT clay ratio up to 5% was shown to affect the color intensity of composite films. It was found that both PVA/AM hydrogels and PVA/AM/MMT composites reached the equilibrium swelling state in water after four hours; however PVA/AM/MMT composites displayed higher swelling than PVA/AM hydrogels. However, the swelling of PVA/AM hydrogels or their composites at the equilibrium state increased with increasing temperature up to 60°C. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Robust and thermo-response graphene–PNIPAm hybrid hydrogels reinforced by hectorite clay

Graphene oxide (GO) based hydrogels were proposed to be used as biomaterials and stimuli-response materials, but their poor mechanical properties restricted their applications. We enhanced GO–poly(N-isopropylacrylamide) (PNIPAm) hydrogels by hybrid with the hectorite clay through in situ polymerization for the first time. This clay was found to stabilize the GO in the aqueous suspension when a reducer was added in a redox initiating pair. These GO–clay–PNIPAm hybrid hydrogels exhibited a high mechanical strength and extensibility with the GO sheets as the cross-linker and with the hectorite clay as both the cross-linker and reinforcing agent. They were thermal-responsive with the volume phase transition at ∼34 °C. Reduction of the GO with l-ascorbic acid under environmental friendly conditions resulted in a high conductivity to the graphene–clay–PNIPAm hydrogels. These graphene–clay–PNIPAm hydrogels still had desirable mechanical properties. This finding has provided an easy method to prepare strong and stimuli-response graphene–polymer hydrogels to meet the demand for the newly developed soft matter.     

Equilibrium swelling behavior and elastic properties of polymer–clay nanocomposite hydrogels

Nanocomposite hydrogels were prepared by free‐radical polymerization of the monomers acrylamide (AAm), N,N‐dimethylacrylamide (DMA), and N‐isopropylacrylamide (NIPA) in aqueous clay dispersions at 21°C. Laponite XLS was used as clay nanoparticles in the hydrogel preparation. The hydrogels based on DMA or NIPA monomers exhibit much larger moduli of elasticity compared with the hydrogels based on AAm monomer. Calculations using the theory of rubber elasticity reveal that, in DMA‐clay or NIPA‐clay nanocomposites, both the effective crosslink density of the hydrogels and the functionality of the clay particles rapidly increase with increasing amount of Laponite up to 10% (w/v). The results suggest that DMA‐clay and NIPA‐clay attractive interactions are stronger than AAm‐clay interactions due to the formation of multiple layers on the nanoparticles through hydrophobic associations. It was also shown that, although the nanocomposite hydrogels do not dissolve in good solvents such as water, they dissolve in dilute aqueous solutions of acetone or poly(ethylene oxide) of molecular weight 10,000 g/mol, demonstrating the physical nature of the crosslink points. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

聚(N-异丙基丙烯酰胺)/海藻酸钠/黏土复合水凝胶的制备及其性能

以无机黏土为交联剂制备了聚（N-异丙基丙烯酰胺）/海藻酸钠/黏土（PINPA/SA/clay）复合水凝胶,通过红外光谱、X射线衍射和SEM对凝胶的结构和形态进行了表征,并研究了凝胶的溶胀动力学和力学性能。结果表明：黏土的结晶结构已被破坏,黏土规整的片层被剥离并在凝胶中无序分布,起到交联剂的作用;随黏土含量的增加,凝胶网络交联密度增加,孔洞的孔径减小,溶胀速度下降。另外,PINPA/SA/clay凝胶显示了良好的力学性能,断裂伸长率超过1000%。