温度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,选用具有优良温敏性的N-异丙基丙烯酰胺(NIPA)为基本原料,制备了温度敏感水凝胶,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了测试.结果表明:温度敏感水凝胶的溶胀受离子强度和温度的影响很大,离子强度越高,溶胀率越低;其机械强度随温度变化显著.     

pH值／电场双重敏感水凝胶的合成及性能测定

从分子设计的角度出发,合成了pH值／电场双重敏感水凝胶,测试了其系列理化性能,包括密度、分子质量、交联密度、固定电荷密度、离解pH值及力学性能等,探讨了离子强度、pH值、电场等因素对水凝胶溶胀率的影响机理及影响趋势。     

聚甲基丙烯酸N,N-二甲基氨基乙酯水凝胶敏感性研究

采用热化学聚合法制备了聚甲基丙烯酸N,N-二甲基氨基乙酯(PDMAEMA)水凝胶,对其溶胀性能进行了研究,考察了温度、pH和离子强度对其溶胀行为的影响.结果表明,PDMAEMA水凝胶具有温度敏感性,其低临界相变温度在50℃左右;水凝胶具有pH敏感性,其溶胀率在pH=8附近有一突变的下降过程;具有离子强度敏感性,溶胀率随离子强度的增加呈线性下降的趋势.     

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。     

温度及pH敏感性聚乙烯醇/羧甲基壳聚糖水凝胶的制备与性能研究

以聚乙烯醇(PVA)和羧甲基壳聚糖(CMCh)为原料,采用60Co-γ射线辐照交联制备聚乙烯醇/羧甲基壳聚糖(PVA/CMCh)水凝胶;研究了PVA与CMCh的配比、温度、pH及离子强度等对PVA/CMCh水凝胶溶胀率的影响。结果表明适当配比的PVA/CMCh水凝胶具有一定的温度、pH及离子敏感性。该水凝胶在5~20°C时具有较高的溶胀率,温度在20°C以上溶胀率较低,并且有一定的可逆性;水凝胶在pH较低(pH<4.0)和较高(pH>6.0)时溶胀率均较大,而当pH为4.0~6.0时溶胀率较小,显示出一定的pH敏感性。     

PASP/SPP水凝胶溶胀性能的研究

采用水溶液聚合法制备聚天冬氨酸/沙柳木粉(PASP/SPP)水凝胶,采用傅里叶红外光谱(FTIR)、X射线衍射(XRD)和扫描电镜(SEM)对其结构进行表征。研究了溶胀时间、溶胀温度、溶液pH值、离子强度等对水凝胶溶胀性能的影响。结果表明,FTIR和XRD显示PASP上的—COOR与沙柳木粉上的O—H发生接枝共聚反应,并形成PASP/SPP水凝胶;SEM显示其表面疏松,有大小不等的孔隙,有利于提高水凝胶的溶胀性能。当溶胀时间为60 min、溶胀温度为30℃、溶液pH值为5.5、离子强度为0时,PASP/SPP水凝胶的溶胀比达到最大,为7.2。     

PASP/SPP水凝胶溶胀性能的研究

采用水溶液聚合法制备聚天冬氨酸/沙柳木粉(PASP/SPP)水凝胶,采用傅里叶红外光谱(FTIR)、X射线衍射(XRD)和扫描电镜(SEM)对其结构进行表征。研究了溶胀时间、溶胀温度、溶液pH值、离子强度等对水凝胶溶胀性能的影响。结果表明,FTIR和XRD显示PASP上的—COOR与沙柳木粉上的O—H发生接枝共聚反应,并形成PASP/SPP水凝胶;SEM显示其表面疏松,有大小不等的孔隙,有利于提高水凝胶的溶胀性能。当溶胀时间为60 min、溶胀温度为30℃、溶液pH值为5.5、离子强度为0时,PASP/SPP水凝胶的溶胀比达到最大,为7.2。     

温度、pH及离子强度敏感性聚氨酯水凝胶的合成与性能研究

以甲苯二异氰酸酯(TDI)、聚乙二醇(PEG-6000)、二羟甲基丙酸(DMPA)及三乙撑四胺(TEFA)等为原料,合成了温度、pH、及离子强度敏感性聚氨酯水凝胶(PUHG)。研究了PUHG溶胀率(SR)受温度(T)、pH、离子强度(I)、交联剂用量等因素的影响。结果表明PUHG的溶胀率在20~45℃的范围内随温度的升高而减小,45℃后不再变化;在酸性(pH4)溶液中收缩,在碱性(pH9)溶液中溶胀,表现出良好的pH值敏感性;在一定温度和pH下,随着离子强度的增加PUHG的溶胀率减小。水凝胶溶胀动力学研究表明,PUHG具有良好的溶胀-退胀可逆性。     

甲基丙烯酸β-羟乙酯共聚水凝胶的合成及性能研究

以HEMA、AAM为共聚单体,采用溶液聚合法合成了HEMA/AAM共聚水凝胶,并对其溶胀动力学、离子强度、温度、pH值等性能进行了测定。实验表明:合成的水凝胶初始溶胀迅速,达到平衡溶胀比平衡约6h;在不同离子强度的水溶液中,随着离子强度I的增大,凝胶的ESR不断降低;在pH<7时,其EKR随pH值的增加而减少,在pH>7时,其ESR随pH值的增加而猛增,因为发生了水解反应;凝胶的ESR随温度的升高而降低。     

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。     

Analysis of a model for pH-sensitive hydrogels

A mathematical model comprising conservation of mass, momentum, and ions for a hydrogel subject to alterations of the solution pH is derived, analyzed, validated and presented. Good agreement between model predictions and their experimental counterpart are achieved. To gain a physical insight into the deformation behavior of the pH-sensitive hydrogel, a scaling analysis coupled with a parametric study is carried out for key physical and operational parameters. The results suggest the significance of initial fixed-charge density, solution ionic strength, Poisson ratio and Young modulus in determining swelling degree of the hydrogel. In addition, it is noted that changes in acid dissociation constant and temperature lead to a notable shift in equilibrium swelling curves. Permeability and size of the hydrogel were found to significantly affect the deformation kinetics: A hydrogel with higher permeability and/or smaller size exhibits faster deformation. These findings and the characteristic scales could provide important guidelines in designing systems utilizing pH-sensitive hydrogels.     

A promising porous polymer-nanoclay hydrogel nanocomposite as water reservoir material: synthesis and kinetic study

A porous hydrogel nanocopmposite based on biodegradable salep and montmorillonite (MMT) was synthesized by in-situ free radical graft polymerization of salep chains with acrylic acid (AA) monomers. The chemical structure and morphological properties of the prepared hydrogels was evaluated by FTIR spectroscopy, X-ray diffraction and SEM techniques. The effect of reaction variables such as crosslinker, initiator, monomer and clay contents on equilibrium water absorption capacity and swelling kinetic of hydrogel were investigated and optimized. Swelling behavior of the hydrogels in various pH and saline solutions was also studied. Incorporation of MMT into hydrogel matrix caused the formation of porous hydrogel network. These porous structures resulted in higher water uptake capacity and swelling rate in hydrogel nanocomposite in comparison to neat hydrogel sample. Moreover, hydrogel nanocomposite sample exhibited proper salt and pH-sensitive behavior. High swelling capacity and rate, porosity, salt and pH sensitivity make hydrogel nanocomposite a profitable candidate in agricultural and horticultural applications, such as water reservoir system.     

pH敏感性P(AAm-co-AA)半互穿网络水凝胶的制备、表征及溶胀动力学研究

以N,N-亚甲基双丙烯酰胺(N,N-MBA)为交联剂、过硫酸钾(KPS)为引发剂,采用自由基交联共聚法合成了具有pH敏感性的半互穿网络水凝胶聚丙烯酰胺-co-丙烯酸[P(AAm-co-AA)],通过傅立叶红外光谱、差热分析研究了水凝胶的结构及热稳定性.水凝胶的溶胀研究表明,随着缓冲溶液pH值的增大平衡溶胀率增大;在不同...     

A facile route to obtain an acidic hydrogel containing lactate moieties

The idea to develop hydrophilic lactic acid-based polyelectrolyte was presented. A facile route was utilized to prepare smart hydrogels that contained lactate units and carboxylic groups. The hydrogels were obtained through the radical cross-linking reaction between an unsaturated lactate-contained macromonomer and acrylic acid (AA)/itaconic acid (IA) monomer pair. The structure and performances of the hydrogels were characterized with thermogravimetric analysis, dynamic thermal analysis, scanning electron microscopy, swelling tests and adsorption measurements. The equilibrium swelling ratios of the hydrogels in acidic (pH 3.6) and basic (pH 11.5) media reached 25.3 and 62.3 respectively. The pH-sensitive swelling behaviors of the hydrogel confirmed that the hydrogels contained carboxylic groups and they were hydrophilic. The metal ions including calcium, copper, lead and cerium ions were bound into the hydrogels, which also confirmed the existence of the carboxyl groups. Moreover, the swelling ratio and adsorption capacity of the gel prepared from monomer pair were significantly higher than those obtained in absence of IA, which suggested that the properties of the hydrogels could be controllable by simply adjusting the ratio of AA/IA. In addition, the weight loss percentage of the hydrogel was around 37% after two-week in vitro degradation, which indicated the hydrogel contained lactate units.     

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。     

温度和pH响应型水凝胶的制备及性能研究

采用双丙酮丙烯酰胺、丙烯酰胺和丙烯酸为原料,以N,N'-亚甲基双丙烯酰胺为交联剂,2-酮戊二酸为光引发剂,采用光引发聚合方法制备了具有温度和pH响应型水凝胶。研究了水凝胶在不同温度和pH条件下的溶胀性能。结果表明,随着温度的升高,水凝胶的溶胀率降低,随着pH的增加,水凝胶的溶胀率增加,表现出明显的温度、pH双重响应性。     

Environmental sensitive hydrogel for purification of waste water: part 1: synthesis and characterization

We report the synthesis of a novel poly (acrylate-acrylic acid-co-maleic acid) hydrogel by the copolymerization of acrylic acid and maleic acid in aqueous media using N,N′-methylenebisacrylamide (NMBA) as cross linker and ammonium persulfate as initiator. Hydrogels with varying concentration of the cross linker and monomer were prepared and were characterized using Fourier transform IR spectroscopy and thermogravimetry. The mechanical properties of the gel were investigated using tensile strength measurements and the morphology was confirmed with environmental scanning electron microscopy at room temperature. Water absorbency studies of the hydrogels revealed that synthesized hydrogels are responsive towards ionic strength and pH of the swelling medium. Cross link density and tensile strength were found to increase with increase in the NMBA content which was optimized from swelling experiments. Reswelling experiments of the hydrogel revealed that the synthesized hydrogel is a reusable material and it indicates its applicability in the waste water purification.     

聚苯胺/碳纳米管杂合水凝胶的合成及膨胀性能研究

合成了一种以甲基丙烯酸-丙烯酰胺共聚网络P(AAm-co-MAA)为基体,以聚苯胺为互穿组分(PANI)的半互穿网络杂合水凝胶。研究表明,当将PANI和MWNTs-COOH被引入到P(AAm-co-MAA)网络中后得到的P(AAm-co-MAA)/PANI/MWCNT-COOH半互穿网络杂合水凝胶则能保持较好的膨胀性,同时发现,依靠调节PA-NI/MWNTs-COOH的含量可以使杂合水凝胶膨胀性增加。这为研究杂合水凝胶的力学性能和pH敏感性提供了一个窗口。     

Salt-, pH- and temperature-responsive semi-interpenetrating polymer network hydrogel based on poly(aspartic acid) and poly(acrylic acid)

In this study, a novel salt-, pH- and temperature-responsive semi-interpenetrating network (semi-IPN) hydrogel, composed of poly(aspartic acid) (PAsp) and poly(acrylic acid) (PAAc), was prepared. PAsp/PAAc semi-IPN hydrogel being ionic in nature, the swelling behavior was significantly influenced by various swelling medium. The structure of the triply responsive hydrogel was studied by Fourier transform infrared spectroscopy (FTIR) and scanning electron microscopy (SEM), and the salt-, temperature- and pH-sensitivities were investigated through measuring equilibrium swelling ratios in various environmental solutions. The results indicate that there is a structure of polyelectrolyte complex in the hydrogel, and that the responsive behaviors of this hydrogel to alternating changes in inorganic salt (different physiological bio-fluids), pH and temperature are improved because of the incorporation of PAsp. In addition, during the repeatable swelling and shrinkage period, the semi-IPN hydrogel shows suitable mechanical strength. The salt-, pH- and temperature-responsive hydrogel will have wider applications in biomedical areas.