壳聚糖水凝胶溶胀性能的研究

壳聚糖水凝胶在pH7.0,0.2%甘氨酸缓冲溶液中的最高溶胀比R为637.5,溶胀体积比Rv为12.75;当pH≤7.0时,表现强的吸水性;pH>8.5时脱水收缩;在<1%NaCl溶液中,表现出不同程度的吸胀性;在≥1%NaCl溶液中,无吸胀性,随着环境温度的升高,吸胀性下降;甲醇作为成胶介质,凝胶的吸胀性最强;交链度与壳聚糖水凝胶的Rv成反比。因此认为,壳聚糖水凝胶在农业、医药、化工和生物学的应用及研究中将表现重要作用。     

聚(丙烯酸)-co-(α-甲基丙烯酸)水凝胶的pH敏感性研究

通过共聚制得聚(丙烯酸)-co-(α-甲基丙烯酸)水凝胶,研究了不同的合成务件下的溶胀率,以及在恒定pH时,交联剂、单体浓度对溶胀率的影响,研究了此凝胶的pH可逆性。     

聚(丙烯酰胺-co-丙烯酸)水凝胶对孔雀石绿的吸附研究

以AM和AA为单体,MBA为交联剂,在水溶液中利用GDEP引发一步制得P(AM-co-AA)水凝胶并研究了其对阳离子型染料MG的吸附特性。考察了pH、吸附时间,初始浓度等因素对吸附性能的影响,同时探讨了可能的吸附机理。结果表明,最佳的吸附pH为5.6,吸附时间为4 h,P(AM-co-AA)水凝胶对MG的吸附行为符合动力学准二级反应和Langmuir吸附等温式,用Langmuir吸附模型计算得到P(AM-co-AA)水凝胶对MG的最大吸附量为934.6 mg/g。     

P(DMAM-co-AA)水凝胶的溶胀行为

采用水溶液聚合法合成了N,N-二甲基丙烯酰胺(DMAM)与丙烯酸(AA)的共聚物[P(DMAM-coAA)]水凝胶,研究了温度、Na Cl浓度、p H值对水凝胶溶胀行为的影响,以及该水凝胶的溶胀与消胀动力学。结果表明:P(DMAM-co-AA)水凝胶的吸水能力随温度和Na Cl浓度升高而下降,在中性条件下的吸水能力较弱,在酸性和碱性条件下吸水能力较强,其溶胀和消胀速率随溶胀时间和消胀时间延长而逐渐降低,约10 h达到平衡状态。     

CMC-P(AA-AM)水凝胶的制备及溶胀性能测定

以羧甲基纤维素钠(CMC)为原料、丙烯酸(AA)和丙烯酰胺(AM)为单体、偶氮二异丁咪唑啉盐酸盐(VA-044)为引发剂、N,N-亚甲基双丙烯酰胺(NMBA)为交联剂制备了CMC-P(AA-AM)水凝胶，研究了聚合条件对其溶胀性能的影响，通过单因素试验确定最佳聚合条件；利用傅里叶红外光谱、热失重对水凝胶结构进行表征；重点考察了水凝胶在不同盐、pH及表面活性剂溶液中的溶胀性能。结果表明，CMC、VA-044、NMBA、AM占AA的质量分数分别为9%、0.7%、0.7%、33.3%时，水凝胶溶胀倍率最大，为253.2 g/g。CMC-P(AA-AM)在不同盐溶液中的溶胀性能差距较大，对重金属离子更为敏感。水凝胶在pH 5～9范围内保持了较高的溶胀性能，表现出良好的pH响应性能。CMC-P(AA-AM)在阴离子表面活性剂溶液中溶胀性能优于非离子、阳离子溶液，在油酸钠中的吸水倍率为210.0 g/g。     

聚乙烯醇水凝胶的制备及其溶胀性能

采用化学交联方法制备了PVA水凝胶，研究了PVA聚合度、醇解度等分子结构参数，反应温度、反应时间等合成工艺参数，交联剂用量、疏水单体用量、阴离子单体用量等化学组成对PVA水凝胶溶胀性能的影响。结果表明，采用聚合度为1700、醇解度为95％的PVA1795为基体，当交联剂用量为1mL，反应温度为80℃，反应时间为8h，所制得的PVA水凝胶具有较高的溶胀率。     

丙烯酰胺/丙烯酸水凝胶的pH敏感性研究

测定并研究了丙烯酰胺／丙烯酸凝胶的pH敏感性，及各因素对其性能的影响，实验表明：当丙烯酰胺／丙烯酸比在2：3附近时，形成的凝胶溶胀比最大；随着交联剂含量的增加，会使凝胶的溶胀比显著减小；引发剂含量适当时，可使凝胶溶胀比达到最大。并且从离子强度、相互反应方面对这种变化进行了解释。     

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。     

Tuning of the swelling and dye removal efficacy of poly(acrylamide-AMPS)-based smart hydrogel

Hydrogels responsive to pH change based on poly(acrylamide-co-2-acrylamido-2-methylpropane sulfonic acid) are synthesized. The hydrogels are characterized in terms of FTIR spectroscopy, swelling–deswelling behavior, morphological analysis and dye removal properties. The swelling of the hydrogel is strongly dependent on the copolymer composition, pH and ionic strength of the medium. The dye removal efficiency (DRE) also depends on the copolymer composition, pH and ionic strength. Pseudo-second-order kinetics and Langmuir isotherms model, respectively, are the best-fit models for the present gel. The cellular structures of the hydrogels are clearly revealed by optical microscopic and SEM images.     

戊二醛对壳聚糖-聚醚水凝胶溶胀动力学的影响

以壳聚糖和聚醚为原料、戊二醛为交联剂合成了壳聚糖-聚醚水凝胶。研究了壳聚糖-聚醚水凝胶溶胀机理,探讨了戊二醛浓度对该水凝胶的溶胀度、溶胀速率和溶胀动力学的影响。结果表明,戊二醛浓度不仅是影响水凝胶溶胀度的主要因素,随着戊二醛浓度的增大,壳聚糖-聚醚水凝胶的溶胀度逐渐减小,而且影响其溶胀动力学类型,当戊二醛浓度为0.107 mol·L^-1,该水凝胶的溶胀过程属于Fickian类型,当戊二醛浓度为0.320、0.533 mol·L^-1,其溶胀过程属于non-Fickian类型。     

The effects of the pH value of the swelling medium on the kinetics of the swelling of a poly(acrylic acid) hydrogel

The isothermal kinetics curves of the swelling of a poly(acrylic acid) hydrogel in buffer solutions of different pH values (5, 7, and 9) at temperatures ranging from 30 to 40°C were determined. The possibilities of applying the Fick kinetics model and the Peppas equation were examined. It was found that the applicability of these models were limited. The kinetics model of a first‐order chemical reaction was found to describe the swelling kinetics of the PAA hydrogel in all the investigated buffer solution at all the investigated temperatures. Swelling kinetics is determined by the rate of expansion of the network. The kinetic parameters (E_a, ln A) of the swelling of the PAA hydrogel in buffer solutions of different pH values were determined. The activation energy and the pre‐exponential factor of the swelling of the PAA hydrogel in buffer medium decreased with increasing pH value of the swelling medium. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

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。     

DMAEMA/NVP/HEMA共聚物水凝胶的合成与性能研究

以甲基丙烯酸N,N-二甲氨基乙酯(DMAEMA)、N-乙烯基吡咯烷酮(NVP)和甲基丙烯酸β-羟乙酯(HEMA)为共聚单体,采用自由基水溶液聚合法制备了化学交联的三元共聚水凝胶,并对水凝胶在不同温度和不同离子强度及不同pH介质中的溶胀性能进行了测定。结果表明,在不同离子强度(I)的水溶液中,随着I的增大,水凝胶的平衡溶胀比ESR不断降低;但当I>0.2后,对凝胶ESR的影响不显著;当外界环境酸度较大(pH<2)时,凝胶ESR较大,但pH值稍有增大,凝胶ESR迅速下降;温度升高,凝胶ESR减少。     

Chitosan modified MMT‐poly(AMPS) nanocomposite hydrogel: Heating effect on swelling and rheological behavior

Vulnerability of hydrogels against thermal circumstances may be substantially eliminated via incorporating nanoclay to prepare nanocomposite hydrogels. In this research, chitosan‐intercalated montmorillonite (ChitoMMT) was used as a bionanoclay to yield novel nanocomposite hydrogels based on 2‐acrylamido‐2‐methylpropanesulfonic acid. The bionanoclay is suitable especially for preparing biomaterials used in biomedical, food, and pharmaceutical applications, unlike conventional commercial nanoclays (alkyl ammonium‐intercalated MMT) which are not appropriate for bio‐applications due to toxicity of the intercalant particularly where the clay content is high. Two different crosslinkers (i.e., methylene bisacrylamide, and polyethyleneglycol dimethacrylate) were employed to synthesize the nanocomposites. The variations in swelling, rheological and thermal properties of the hydrogels were essentially attributed to thermally induced crosslink cleavage/formation depending upon the crosslinker nature. The nanocomposites comprised superior thermal properties in comparison with the clay‐free hydrogel counterpart. They can preserve substantially their swelling ability for longer heating periods. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Influence of temperature on swelling and mechanical properties of a sulphobetaine hydrogel

The swelling and mechanical properties of a hydrogel based on the zwitterionic monomer N,N-dimethyl-N-methacryloyloxyethyl-N-(3-sulphopropyl)ammonium betaine crosslinked with ethylene glycol dimethacrylate have been determined as a function of temperature. The volumetric swelling has been found to decrease slightly with temperature. On the other hand, the Young's modulus as well as the experimental crosslink density increase with temperature. The results obtained have been explained by examining the changes with temperature of the partial molar Gibbs free energy of dilution in conjunction with the variation of its enthalpic and entropic contributions.     

NVP接枝壳聚糖水凝胶的合成与溶胀性能

合成了N-乙烯基吡咯烷酮（NVP）接枝壳聚糖（CHI）水凝胶,讨论了NVP/CHI、引发剂、交联剂、聚合温度、乙酸浓度等因素对接枝率及凝胶溶胀性能的影响,NVP∶CHI为6时,接枝率达到300%以上. 溶胀温度、pH值、盐浓度等对凝胶溶胀性能的影响实验表明,凝胶表现出温度敏感性,在40 ℃出现最大平衡溶胀率,并观察到一级相转变;在中性或弱酸性介质中溶胀性能较好;与PVP凝胶相比,NVP接枝CHI凝胶表现出反聚电解质效应. 溶胀动力学研究表明,在溶胀前期,CHI含量较高时,凝胶趋向于非Fick溶胀,说明除了溶剂扩散外,凝胶网络链段弛豫、水分子与凝胶网络间及凝胶高分子链段间相互作用对凝胶溶胀性能的影响至关重要;CHI含量较高时则趋向于Fick溶胀.     

A convenient one‐step preparation of chitosan‐poly(sodium acrylate‐co‐acrylamide) hydrogel hybrids with super‐swelling properties

Hydrogel hybrids were conveniently prepared from alkaline hydrolysis of chitosan–poly(acrylonitrile) mixture under highly practical conditions. The reaction of chitosan alkoxide anions with nitrile groups of poly(acrylonitrile) (PAN) forms crosslinking points and results in a three‐dimensional network with superswelling ability in aqueous media. The hydrogel hybrid was identified using FTIR spectroscopy. The PAN content of the hydrolyzing feed affects proportionally the swelling capacity of the hydrogel hybrid. The swelling properties (capacity and rate) of the ampholytic hydrogel were investigated preliminarily. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 99: 1615–1619, 2006