新型温度/pH敏感性ABA型三嵌段共聚物的合成、胶束化及凝胶化行为研究

采用原子转移自由基聚合（ATRP）方法合成了水溶性良好的不同聚合度的三嵌段共聚物P（DEAEMA-co-MEO₂MA-co-HMAM）-b-PEG-b-P（DEAEMA-co-MEO₂MA-co-HMAM）. 利用傅里叶变换红外光谱（FT-IR）、核磁共振氢谱（¹H NMR）以及凝胶渗透色谱（GPC）对聚合物结构及组成进行表征;通过透光率、表面张力的测定以及动态光散射（DLS）、荧光探针和透射电镜（TEM）技术研究了共聚物水溶液的性质及胶束化行为. 通过对不同pH下共聚物的凝胶状态和不同pH下温度诱导的溶胶-凝胶转变过程的观察,研究了温度和pH对共聚物凝胶化行为的影响. 测定了载药凝胶分别在不同温度和不同pH的缓冲溶液中对药物的累积释放率. 结果表明：ABA型三嵌段共聚物具有良好的温敏性和pH敏感性,在温度或pH诱导下可形成核壳胶束和凝胶. 载药凝胶对药物的累积释放率随温度和pH的降低而升高.     

温度及pH敏感N-异丙基丙烯酰胺/β-环糊精水凝胶的合成与性能研究

用顺丁烯二酸酐 (MAH)对具有分子包结能力的 β 环糊精 (β CD)进行化学改性 ,合成出了丁烯二酸单酯化 β CD单体 (MAH β CD) .通过氧化还原自由基引发MAH β CD与N 异丙基丙烯酰胺 (NIPA)聚合 ,合成出含 β CD结构单元的新型水凝胶 .用核磁共振、红外光谱及元素分析对MAH β CD单体及共聚物的结构和组成进行了表征 .溶胀研究结果表明 ,该水凝胶具有较好的pH、温度及离子强度敏感性 ;并且水凝胶在较高羧基(—COOH)含量和弱碱环境中 ,仍能表现出明显的温敏性     

明胶-聚异丙基丙烯酰胺水凝胶的pH、温度敏感性

用明胶(Gel)和N 异丙基丙烯酰胺(NIPAM)为原料,制备了Gel/聚异丙基丙烯酰胺(PNIPAM)水凝胶;研究了不同含量的水凝胶的温度、pH敏感性。结果表明:温度对水凝胶pH敏感性的影响取决于水凝胶的组成。明胶含量高的水凝胶,其pH敏感性几乎不受温度的影响;当0.500.90时,pH值几乎不影响水凝胶的温敏性。     

温度和pH敏感P(NIPA-co-AA)/粘土复合水凝胶的辐射制备与表征

以N-异丙基丙烯酰胺(NIPA)作为温敏性聚合单体,丙烯酸(AA)为pH敏感性单体,有机粘土为改性剂,采用~(60)Co-γ射线为辐射源,辐射合成了P(NIPA-co-AA),粘土复合水凝胶,研究了粘土的加入对水凝胶溶胀率、温度及pH敏感性和压缩性能的影响.结果表明,P(NIPA-co-AA)/粘土复合水凝胶的溶胀性能优于P(NIPA-co-AA)水凝胶,平衡溶胀率(SR)明显提高;且复合水凝胶仍表现出明显的温度和pH敏感性;粘土的加入提高了水凝胶的压缩强度、最大压缩力和压缩屈服力等力学性能,当粘土含量为15%时,P(NIPA-co-AA)/粘土复合水凝胶的压缩强度为P(NIPA-co-AA)共聚水凝胶的2.4倍,最大压缩力为P(NIPA-co-AA)的2.1倍.     

明胶-聚异丙基丙烯酰胺水凝胶的溶胀动力学

采用明胶（Gel)和N－异丙基丙烯酰胺（NIPAM）为原料，制备了Gel/聚异丙基丙烯酰胺（PNIPAM）水凝胶系列；研究了原料配比、pH值及温度对水凝胶溶胀速度的影响。结果表明，当温度大于PNIPAM的最低临界溶液温度（LCST）值时，Gel/PNIPAM水凝胶的溶胀速度随着组分中PNIPAM的增加而降低，且溶胀过程以扩散渗透控制为主。而pH对水凝胶溶胀速度的影响与温度有关。Gel/PNIPAM配比为5／5，温度大于LCST时，水凝胶的pH敏感性受明胶控制；温度低于LCST时，pH对水凝胶的溶胀速度的影响很小。     

聚丙烯酰胺/聚异丙基丙烯酰胺互穿网络水凝胶的制备与性能

采用分步法用电子加速器辐射合成了聚丙烯酰胺(PAAm)/聚异丙基丙烯酰胺(PNIPAAm)互穿网络水凝胶,并考察了温度、pH值、离子强度对其溶胀性能的影响.研究表明:互穿水凝胶具有温度敏感性,且其体积相变与互穿网络中PAAm和PNIPAAm含量有关,随着网络中PAAm含量的增加水凝胶的体积相变趋于平缓,可以通过改变PAAm和PNIPAAm的组成比来控制水凝胶的体积相变行为.此外,互穿水凝胶还具有pH敏感性和一定的抗盐性.     

温度与pH快速响应性P(NIPAM-co-AAc)水凝胶的制备及其性能

以氯化钠水溶液作为反应介质,成功制备了温度与pH快速响应性聚(N-异丙基丙烯酰胺-co-丙烯酸)[P(NIPAM-co-AAc)]水凝胶,研究了氯化钠水溶液的浓度对凝胶性能的影响.通过红外光谱(FT-IR)、扫描电镜(SEM)、测溶胀比对凝胶性能进行了表征.结果表明:凝胶具有相同的化学组成与结构,但具有不同的微观形态;随着反应介质中氯化钠浓度的增加,凝胶在20℃蒸馏水中的平衡溶胀比增大,并表现出较强的温度与pH敏感性以及较快的去溶胀速率.     

温度/pH敏感性接枝共聚物水凝胶P(DMAEMA-g-NIPAM)的 合成及性质研究

利用大分子单体技术, 采用自由基溶液聚合合成了温度/pH敏感性聚甲基丙烯酸-N,N-二甲氨基乙酯接枝聚N-异丙基丙烯酰胺[P(DMAEMA-g-NIPAM)]水凝胶. 用红外光谱及扫描电镜对凝胶的组成及形貌进行了表征. 凝胶的去溶胀和溶胀动力学研究表明, 所合成的凝胶具有温度和pH敏感性. 与传统的聚丙烯酸系水凝胶相比, P(DMAEMA-g- NIPAM)具有相反的pH敏感性; P(DMAEMA-g-NIPAM)凝胶在55 ℃时具有较快的去溶胀速率, 随着凝胶中接枝链PNIPAM量的增加, 凝胶的去溶胀速率加快.     

AMPS/DMAM/FA/AM共聚物的合成及溶液性能研究

本文采用氧化还原引发体系合成了AMPS（2-丙烯酰胺基-2-甲基丙烷磺酸钠）／DMAA（N,N-二甲基丙烯酰胺）／FA（富马酸）／AM（丙烯酰胺）共聚物,研究了共聚物的水溶液性能。结果表明,随聚合物浓度的增加,溶液表观粘度急剧增加;无机盐的加入使聚合物溶液的粘度下降,但很快稳定;随老化温度的提高,聚合物溶液的粘度有所增加;共聚物试样在盐水中表现出随剪切速率的增加,表观粘度增加。     

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.     

Non-Gaussian elasticity of swollen poly(N-isopropylacrylamide) gels at high charge densities

Modulus of elasticity of highly charged N-isopropylacrylamide (NIPA) based hydrogels (PNIPA) are measured at various swelling degrees in water. The sodium salt of 2-acrylamido-2-methylpropane sulfonic acid (AMPS) was used as the ionic comonomer of NIPA in the hydrogel preparation. The mole fraction of AMPS in the comonomer feed was varied between 0 and 1, while the crosslinker ratio was fixed at 1/85. The elasticity data show that the equilibrium swollen PNIPA hydrogels are in the non-Gaussian regime. Equations were derived based on the inverse Langevin function for the swelling ratio and the modulus of highly charged PNIPA hydrogels and checked by experiments. Results of calculations show good agreement to the swelling and elasticity data of highly swollen PNIPA gels.     

Synthesis and Swelling Behaviors of P(AMPS-co-AAc) Superabsorbent Hydrogel Produced by Glow-Discharge Electrolysis Plasma

Highly swelling P(2-acrylamido-2-methyl-1-propanesulfonic acid- co-acrylic acid) (P(AMPS-co-AAc)) superabsorbent hydrogel was synthesized in aqueous solution by a simple one-step using glow-discharge electrolysis plasma technique, in which N,N’-methylenebisacrylamide was used as a crosslinking agent. The structure, thermal stability and morphology of P(AMPS-co-AAc) superabsorbent hydrogel were characterized by Fourier transform infrared spectroscopy, thermogravimetric analysis, and scanning electron microscopy. A mechanism for synthesis of P(AMPS-co-AAc) superabsorbent hydrogel was proposed. The reaction parameters affecting the equilibrium swelling (i.e., discharge voltage, discharge time, macroscopic temperature of the liquid phase, mass ratio of AMPS to AAc, and content of crosslinker) were systematically optimized to achieve a superabsorbent hydrogel with a maximum swelling capacity. The hydrogel formed which absorbed about 1,685 g H₂O/g dry hydrogel of the optimized product was used to study the influence of various pH values and salts solutions (NaCl, KCl, MgCl₂, and CaCl₂) on the equilibrium swelling. In addition, swelling kinetics in distilled water and on–off switching behavior were preliminarily investigated. The results showed that superabsorbent hydrogel was responsive to the pH and salts.     

Preparation and characterization of poly(2-acrylamido-2-methylpropane-sulfonic acid)/Chitosan hydrogel using gamma irradiation and its application in wastewater treatment

Radiation grafting of chitosan with 2-acrylamido-2-methyl propane sulfonic acid (AMPS) has been successfully performed. The effect of absorbed dose (kGy) and the chitosan:AMPS ratio on graft hydrogelization was studied. The structure of the prepared hydrogel was confirmed using infrared spectroscopy (IR). Thermal properties were simultaneously studied by thermogravimetric analysis (TGA). The effect of the polymerization variables on the swelling % of the prepared hydrogel was investigated. The highest equilibrium degree of swelling (38.6 g/g) and gel % (94.7%) of the prepared chitosan–AMPS hydrogel was at 40% AMPS and absorbed dose of 10 kGy. The removal of methylene blue, acid red dye, Cd (II) and Cr (III) from composed wastewater was also investigated. The effect of pH, the chitosan:AMPS ratio and the concentration of the pollutant on the adsorption process were studied.     

Synthesis of cross-linked carboxymethyl cellulose and poly (2-acrylamido-2-methylpropane sulfonic acid) hydrogel for sustained drug release optimized by Box-Behnken Design

This research aims to fabricate and characterize chemically crosslinked CMC/PVP-co-poly (AMPS) based hydrogel for the sustained release of model drug metoprolol tartrate through the free radical polymerization technique. Box-Behnken Design was used to optimize CMC/PVP-co-poly (AMPS) hydrogel by varying the content of reactants such as; polymers (CMC and PVP), monomer (AMPS), and crosslinker (EGDMA). Carboxymethyl cellulose (CMC) was crosslinked chemically with AMPS with a constant ratio of PVP by the ethylene glycol dimethacrylate as the crosslinker in the presence of sodium hydrogen sulfite (SHS)/ammonium peroxodisulfate (APS) as initiators. After developing CMC-based hydrogels using different polymers, monomer, and crosslinker concentrations, this study encompassed dynamic swelling, sol–gel fraction, drug release and chemical characterizations such as FTIR, XRD, TGA, DSC, and SEM. In vitro drug release and swelling were performed at 1.2 and 6.8 pH to determine the sustained release pattern and pH-responsive behavior. These parameters depended on the crosslinker, polymer, and monomer ratios used in the formulation development. XRD, SEM, and FTIR showed the successful grafting of constituents resulting in the formation of a stable hydrogel. DSC and TGA confirmed the thermodynamic stability of the hydrogel. Hydrogel swelling was increased with an increase in the ratio of monomer; however, an increase in the ratio of polymer and crosslinker decreased the hydrogel swelling. In vitro gel fraction and drug release also depended on polymer, monomer, and crosslinker ratios. The fabricated CMC/PVP-co-poly (AMPS) hydrogels constituted a potential system for sustained drug delivery.     

Preparation and separation function of N‐isopropylacrylamide copolymer hydrogels

In this paper, N‐isopropylacrylamide (NIPA) was synthesized by acrylonitrile and isopropanol. Poly(N‐isopropylacrylamide) (PNIPA) was prepared by a chemical method. The dependence of its swelling behavior on temperature was studied. Results showed that PNIPA hydrogel was a temperature‐sensitive gel. Its LCST (lower critical solution temperature) was about 32 °C, and its swelling ratio (at 20 °C) was about 17–18. Sodium acrylate (SA) and sodium methylacrylate (SMA) were copolymerized with NIPA respectively. Equilibrium swelling ratios of the copolymer hydrogels at lower temperature were two to three times that of PNIPA. The LCST of the copolymer hydrogels could be controlled between 32 and 45 °C by adjusting the content of SA or SMA. Kinetics of P(NIPA‐co‐SA) hydrogels, whether swelling or shrinking processes, were in good agreement with apparent second order kinetic equations. Several experiments were designed to separate aqueous bovine serum albumin solution using the hydrogels prepared above. The separation efficiency was about 80%. Copyright © 2000 John Wiley & Sons, Ltd.     

高强度PAMPS-PAAm互穿网络凝胶及其溶胀性能

通过考察不同单体浓度或离子强度下凝胶的力学性能和溶胀特性,对聚2-丙烯酰胺-2-甲基丙磺酸(PAMPS)与聚丙烯酰胺(PAAm)形成的互穿网络凝胶的高强度性能和作用机理进行了研究.结果表明:PAMPS-PAAm互穿网络凝胶的力学强度对c(AMPS)存在一个最佳值(1 mol/L),且随c(AAM)的增大而显著增大(0.5～4 mol/L).当c(AMPS)=1 mol/L、c(AAM)＝4 mol/L时,互穿网络凝胶的最大抗压强度达6.46 MPa;改变凝胶体系内水的离子强度,PAMPS-PAAm凝胶在0.25 mol/kg离子强度时的抗压强度与纯水状态下相比增加了29%.     

pH敏感的聚(L-谷氨酸)-交联聚丙烯酸水凝胶的合成与性能研究

通过在聚L-谷氨酸侧链部分接枝甲基丙烯酸2-羟乙酯得到含有双键的聚(L-谷氨酸),将其与丙烯酸共聚得到由聚(L-谷氨酸)侧链接枝并交联聚丙烯酸的pH敏感水凝胶.研究水凝胶在不同pH的缓冲溶液中的溶胀性、溶胀动力学,并通过SEM观察水凝胶的微观结构.结果表明,水凝胶在低pH环境下的溶胀率明显低于高pH环境中的溶胀率,不同...     

Preparation and Characterization of pH-sensitive Hydrogel Film of Chitosan/Poly(acrylic acid) Copolymer

A hydrogel film of chitosan/poly(acrylic acid) (CS/PAAc) copolymer with the property of pH sensitivity, was prepared by irradiating the chitosan film, which was then swelled by aqueous AAc solutions of different concentrations. The effects of the feed ratio of chitosan and AAc on the properties of the hydrogels, such as swelling ratio and pH-sensitivity, were determined. Fourier transform infrared (FT-IR) spectroscopy was applied in the attenuated total reflectance (ATR) mode for analyzing the structure change of the hydrogels after the treatment in buffer solutions of different pHs.     

In situ metal particle preparation in cross-linked poly(2-acrylamido-2-methyl-1-propansulfonic acid) hydrogel networks

Anionic hydrogels of poly(2-acrylamido-2-methyl-1-propansulfonic acid) (p(AMPS)) were prepared with a different amount of cross-linker extent and used for in situ preparation of magnetic and metal particles. The metal particles with various sizes were obtained inside the three-dimensional polymer matrixes by absorption of the corresponding metal ions from their aqueous solutions followed by the reduction in the presence of strong reducing agent. In addition to iron particles, cobalt, nickel, copper nanoparticles, and CdS, quantum dot has been prepared by utilizing hydrogel matrix as a template for inorganic/organic composite synthesis. It was observed that the amount of cross-linkers (0.5%, 0.75%, and 1% with respect to monomer mole ratio) used in this study for bare p(AMPS) has not significantly influenced the morphology of the hydrogels or the size of the iron particles while having great effect on swelling of p(AMPS) hydrogels in water. Copolymeric hydrogels of AMPS with acrylamide in different composition were also prepared. Thermogravimetric analysis and transmission electron microscopy results showed that the AMPS content of the copolymeric hydrogel has great impact on both the metal ion loading capacity and the size of the resultant metal particles.     

Enhanced swelling and adsorption properties of AAm‐AMPSNa/clay hydrogel nanocomposites for heavy metal ion removal

Novel type hydrogel‐clay nanocomposites based on the acrylamide (AAm)‐ 2‐acrylamido‐ 2‐methylpropane sulfonic acid (AMPS) sodium salt and clay were synthesized via in situ copolymerization in aqueous solution. Samples were characterized by determining total basic group (TGB) content and swelling degree, XRD analysis, and FTIR spectroscopy. Effects of monomer ratio and clay amount on the swelling properties of the samples were investigated. It was found that the hydrogel/clay nanocomposites exhibited improved swelling capacity compared with the hydrogels. Samples were used to remove heavy metal ions (Cu (II), Cd (II), and Pb (II)) from aqueous solution in competitive and non‐competitive conditions for the first time. The effects of time and pH of the initial metal ion solution on the adsorption capacity were investigated and selectivity properties of the samples were evaluated. It was found that incorporation of a low amount of clay (10% (wt)) into the polymer structure increased the heavy metal ion adsorption capacity of the sample. It was concluded that the AAm‐AMPS/clay nanocomposites could be used as novel type, fast‐responsive, and high capacity sorbent materials in heavy metal removing processes. Copyright © 2007 John Wiley & Sons, Ltd.