PAA/PNIPAAm互穿网络水凝胶的微波合成与性能研究

以微波为辐射源,对丙烯酸(AA)水溶液进行辐照制得了PAA水凝胶。将脱水后的PAA水凝胶浸泡于含引发剂过硫酸钾(K_2S_2O_8)和交联剂N,N’-亚甲基双丙烯酰胺(BIS)的N-异丙基丙烯酰胺(NIPAAm)水溶液中,待溶胀平衡后取出,进行第二次微波辐照反应,制备了聚丙烯酸/聚N-异丙基丙烯酰胺互穿聚合物网络(PAA/PNIPAAm IPN)水凝胶,并对其溶胀性能进行了研究。研究结果表明,合成的IPN水凝胶兼具pH敏感性和温度敏感性,有望在药物控制释放领域得到应用。     

空心玻璃微珠对聚丙烯酸水凝胶溶胀性能的影响

为了研究空心玻璃微珠(HGM)的加入对合成聚丙烯酸(PAA)水凝胶的吸水溶胀性、耐盐性及pH敏感性的影响,以丙烯酸(AA)为单体、聚乙二醇为有机致孔剂、HGM为无机致孔剂、过硫酸铵为引发剂、N,N-亚甲基双丙烯酰胺为交联剂,通过自由基溶液聚合制备了5种不同HGM投料量的PAA水凝胶,并对其结构、热稳定性、表面形貌以及其在纯水、生理盐水和pH缓冲液中的溶胀行为进行了表征。结果表明,HGM的加入并不影响PAA水凝胶的化学组成和热稳定性,但有利于凝胶致孔;适量HGM的加入有助于大幅提高PAA水凝胶的吸水溶胀性、耐盐性和pH敏感性;当HGM的投料量为单体AA质量的10%时,PAA水凝胶的孔结构最丰富,其吸水平衡溶胀比可达345 g/g,吸盐水平衡溶胀比为47 g/g,pH敏感性在5种水凝胶中最佳。     

AM/PVP互穿网络结构树脂的制备及其性能

通过用MBA做引发剂,APS做交联剂,运用前端聚合制备聚丙烯酰胺(AM)/聚乙烯吡咯烷酮(PVP)互穿水凝胶,进而研究配比的不同对水凝胶的性能差异:用红外光谱表征互穿网络水凝胶的结构性能。当溶剂水的含量及交联剂,引发剂的含量均不变的情况下,调整PVP的含量使其含量从占单体的0%~40%时水凝胶的性能。随着PVP含量的依次增加,吸水速率从800g/g减到550 g/g,吸盐水速率从267 g/g减到183 g/g。当AM与PVP的含量及交联剂,引发剂的含量均不变的情况下,调整溶剂水的含量,从16~20 m L时水凝胶的性能。随着水含量的依次增加,水凝胶的,吸水率从756~402 g/g,吸盐水速率从252 g/g减到134 g/g。当AM与PVP的含量及交联剂,水的含量均不变的情况下,调整引发剂APS的含量,从0.23~0.27 g时水凝胶的性能。随着引发剂APS含量的依次增加,吸水速率和吸盐水速率都是先增大后减小。将前端聚合与常规聚合方法进行了对比。     

pH敏感瓜胶/聚丙烯酸半互穿网络水凝胶研究

制备了瓜胶/聚丙烯酸(GG/PAA)的半互穿网络(sem i-IPN)水凝胶,以N,N-亚甲基双丙烯酰胺(MBA)为交联剂,考察了加料量、溶胀介质pH对平衡溶胀率(ESR)的影响。结果表明:GG/PAA半互穿网络水凝胶的ESR在pH≤3时较小,pH>4后增加较快,pH=8.2时达最大值,继续增加pH,ESR又呈下降趋势,体系具有pH敏感性。在pH相同条件下,ESR随GG用量增加而减小,随丙烯酸(AA)用量增加而增大。pH=8.2、ρ(GG)从5 g/L增加到25 g/L时,ESR从3 142降低到1 026;当ρ(AA)用量从125 g/L增加到375 g/L时,ESR从1 195增加到2 611。m(MBA)∶m(AA)=(0.5∶100)~(1.2∶100)时,ESR略有增加。GG/PAA半互穿网络水凝胶的溶胀动力学表明,该类凝胶满足在胃液pH环境中溶胀率较小、小肠部位pH环境中溶胀率较高的要求,因此,通过调整配方,结合瓜胶只被结肠部位细菌降解的特性,GG/PAA半互穿网络水凝胶有望成为一种理想的靶向结肠给药载体。     

温度及pH敏感生物水凝胶的研究

运用互穿网络技术,合成了具有温敏性的聚(N 异丙基丙烯酰胺)(PNIPAm)和生物大分子明胶(gelatin)的互穿网络聚合物(PNIPAm/Gelatinsemi IPN和PNIPAm/GelatinIPN)水凝胶,该水凝胶的最低临界溶液温度(LCST)与PNIPAm水凝胶的LCST基本相同,均为33℃左右,但在LCST以下的平衡溶胀率减小、相变区域略微变宽。在此基础上,通过N 异丙基丙烯酰胺(NIPAm)与丙烯酸(AAc)交联共聚,改变了水凝胶的LCST,在pH=4 0的缓冲溶液中,各水凝胶的溶胀行为基本一致,与AAc含量无关,LCST都为28℃左右;在pH>4 0的缓冲溶液中,LCST随AAc组分含量的增加而增加,但温敏性减小。同时,AAc的加入,使水凝胶具有pH敏感性,敏感点为pH=4 5左右。还考察了该水凝胶降解的特点:戊二醛(GA)交联后的明胶网络,保留了明胶的生物降解性,但互穿网络水凝胶在实验条件下几乎未被胃蛋白酶和胰蛋白酶降解,在pH=9 6的碱性条件下,水凝胶可发生化学降解。     

活性炭对聚丙烯酸水凝胶pH敏感性的影响

以丙烯酸(AA)为单体、活性炭(AC)为惰性致孔剂、N,N-亚甲基双丙烯酰胺为交联剂、过硫酸铵为引发剂,采用自由基溶液聚合法制备了聚丙烯酸(PAA)/AC复合水凝胶,并研究了AC的引入对PAA水凝胶pH敏感性的影响以及不同pH值的缓冲液中水凝胶的溶胀动力学。结果表明:AC的引入并未影响PAA水凝胶的化学组成和热稳定性,但增大了其孔隙尺寸;AC的引入提高了PAA水凝胶的pH敏感性;冻干的PAA/AC复合水凝胶比烘干的PAA/AC复合水凝胶达到溶胀平衡的速率更快、平衡溶胀比更大。     

具有pH及温度敏感性的互穿网络水凝胶的合成及其性能研究

用自由基聚合合成了具有两亲性的N-异丙基丙烯酰胺(NIPAm)与衣康酸(IA)共聚物水凝胶(NIPAm-co-IA),利用互穿网络(IPN)技术合成了壳聚糖(CS)异丙基丙烯酰胺与衣康酸互穿网络水凝胶IPN(CS/NIPAm-co-IA).研究表明, IPN(CS/NIPAm-co-IA)水凝胶具有良好的pH及温度敏感性,研究了其对辅酶A的控制释放,发现其对辅酶A具有良好的控制释放作用.     

改性聚天冬氨酸/聚丙烯酸/羧甲基纤维素复合高吸水性树脂的制备和性能研究

以改性聚天冬氨酸（KPAsp）、丙烯酸(AA)和羧甲基纤维素(CMC)为原料,采用水溶液聚合法合成改性聚天冬氨酸/聚丙烯酸/羧甲基纤维素(KPAsp/PAA/CMC)复合高吸水性树脂。通过红外光谱（FTIR）、热重分析(TGA)和扫描电镜（SEM）对产物组成结构、热稳定性和表面形态进行表征。探讨了CMC和AA用量对复合高吸水性树脂吸液性能的影响,结果表明当m(CMC)/m(AA)/m(KPSI)=0.15:3:1时,树脂的吸液性能最佳,在去离子水和0.9% NaCl溶液中的吸水倍率分别达到830 g/g和130 g/g。研究了不同组成KPAsp/PAA/CMC吸水性树脂的盐敏感性、温度敏感性和pH敏感性,以及树脂在人工血、人工尿和不同浓度乙醇水溶液的吸液性能,结果表明复合树脂盐敏感性提高,在盐溶液中的吸液倍率为NaCl>FeCl3>CaCl2;低临界溶解温度(LCST)比KPAsp提高了15℃;在溶液pH=5和pH=9出现了两吸液高峰;在人工血和人工尿中的吸液倍率最大为211 g/g和142 g/g,在50%的乙醇水溶液中吸液倍率最大为295 g/g。     

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...     

聚（丙烯酸-醋酸乙烯酯）- 聚乙烯醇互穿网络高吸水性树脂的合成

以丙烯酸(AA)、醋酸乙烯酯(VAc)、聚乙烯醇(PVA)为原料,过硫酸钾为引发剂,N,N-亚甲基双丙烯酰胺为交联剂,环己烷作为油相,span60为分散剂,采用反相悬浮法制备出聚(丙烯酸-醋酸乙烯酯)-聚乙烯醇互穿网络(IPN)高吸水性树脂。研究了丙烯酸中和度、单体物料比、引发剂用量、交联剂用量、反应时间以及聚乙烯醇用量对高吸水性树脂吸液倍率的影响。筛选出了最佳工艺条件为:丙烯酸中和度为70%,丙烯酸与醋酸乙烯酯质量比为3∶1,引发剂质量分数为0.4%,交联剂质量分数为0.035%,反应温度为70℃,PVA质量分数为8%。在最佳工艺条件下,树脂对蒸馏水和质量分数0.9%生理盐水的吸液倍率分别为1 889 g/g和124 g/g,具有良好的吸水性。并用红外光谱仪、扫描电镜、热重分析仪对其结构进行了表征。     

聚天冬氨酸水凝胶的研究与应用进展

聚天冬氨酸（PASP）水凝胶由于其良好的生物相容性、生物降解性及吸水、保水性引起了众多科研工作者的关注。本文首先综述了PASP水凝胶的合成方法，并对比了各自的优势和不足。在此基础上，介绍了本文作者课题组开发的水相均相交联工艺，此工艺具有污染小、成本低的优势，并初步实现了工业化生产，产品的吸水倍率可达300~1000g/g。此外，本文还综述了PASP水凝胶的共混/共聚改性及其在农业及生态修复、环境保护的应用，并着重介绍了PASP的结构可设计性及其在生物医学领域的相关应用研究。其中，本文作者课题组针对PASP水凝胶的吸水保水特性，持续开展了其作为农林保水剂的研究，并得到了良好的试验结果，为大规模应用提供了有益的参考。最后针对PASP性能、合成工艺和应用领域的关联性，归纳了PASP水凝胶亟待解决的问题。本文的阐述将为PASP水凝胶的合成、应用和推广等研究工作提供指导和参考。     

Comparative delivery of Diltiazem hydrochloride through synthesized polymer: Hydrogel and hydrogel microspheres

In this study, interpenetrating polymer network (IPN) hydrogel based on polyvinyl alcohol (PVA) networking with polyacrylic acid (PAA) were prepared by a non‐conventional emulsion method without any added crosslinker, using benzoyl peroxide as initiator and sodium chloride (NaCl) as additive. The IPN hydrogel was characterized by using Fourier transformed infrared (FTIR) spectrophotometry, Thermo gravimetric analysis (TGA), and Scanning electron microscopy (SEM). (PVA‐co‐PAA)/NaCl normal IPN hydrogel (H) were fabricated into hydrogel microspheres (HM) by modified emulsion crosslinking method using glutaraldehyde‐saturated toluene as crosslinker and were loaded with Diltiazem hydrochloride (DL). The IPN hydrogel showed more swelling in simulated intestinal fluid (SIF). (PVA‐co‐PAA)/NaCl HM formulation A1 showed comparatively higher DL entrapment (79%) and better control over DL release up to 24 h. By comparing antihypertensive activity of DL loaded two formulations in normotensive rats, HM formulation A1 found more effective in reducing blood pressure to 40.1%. The experimental results demonstrated that (PVA‐co‐PAA)/NaCl HM had the greater potential than normal hydrogel to be used as a drug carrier. A single use of the prepared hydrogel microsphere system of DL can effectively control hypertension in rats. The system holds promise for clinical studies. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

The swelling behaviors and network parameters of cationic starch‐g‐acrylic acid/poly(dimethyldiallylammonium chloride) semi‐interpenetrating polymer networks hydrogels

Amphiphilic semi‐interpenetrating polymer networks (semi‐IPN) hydrogels were prepared by a sequential‐IPN method by acrylic acid graft copolymerization into cationic starch in mild aqueous media of poly(dimethyldiallylammonium chloride). Some main factors were investigated to evaluate the swelling of hydrogels, and the network parameters M_c were given accordingly to elaborate the interaction between polymers. The chemical structure of the resulting hydrogel was confirmed using Fourier transform infrared spectroscopy. The cationic starch‐based semi‐IPN hydrogels achieved a high swelling capacity of 1070 g/g in deionized water and 94 g/g in 0.9 wt % NaCl solution, respectively) and high compressive stress in a high water content. Besides, a different pH‐dependent behavior was found for this semi‐IPN hydrogel. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

pH-sensitive IPN hydrogel based on poly (aspartic acid) and poly (vinyl alcohol) for controlled release

Various pH-sensitive sequential interpenetrating polymer network (IPN) hydrogels were prepared by introducing poly (vinyl alcohol) (PVA) hydrogel into Poly (aspartic acid) (PASP) hydrogel by freeze-thawing treatment to obtain a novel drug delivery system to the intestine. The structure and the morphologies of the prepared hydrogels were studied by Fourier Transform Infrared Spectroscopy (FTIR) and scanning electron microscopy (SEM). The thermal behavior and crystallinity of the hydrogels were characterized by differential scanning calorimetry (DSC) and X-ray diffraction (XRD). Their pH-sensitive properties moreover were studied and the results revealed that both PASP hydrogel and IPN hydrogels exhibited excellent pH-sensitivity. Furthermore, the controlled drug release properties of the hydrogels were also evaluated and results indicated that by increasing the PVA fraction in the IPN hydrogel, the release of Naproxen sodium was improved. These results show that the IPN hydrogels could be a suitable carrier for site-specific drug delivery in the intestine.     

Synthesis and Characterization of Poly(acrylic acid)/Poly(vinyl alcohol)-xanthan Gum Interpenetrating Network (IPN) Superabsorbent Polymeric Composites

Initially interpenetrating network (IPN) hydrogel was prepared by dispersing xanthan gum (XG) into poly(vinyl alcohol) (PVA) backbone in an aqueous medium. Polyacrylic acid (PAA)/Poly (vinyl alcohol)-Xanthan gum IPN superabsorbent composite were fabricated well by dispersing the prepared IPN hydrogel in acrylic acid and polymerized in a complete aqueous environment through chemical cross-linking method. These superabsorbent polymeric composites were analytically evaluated by scanning electron microscopy (SEM), Fourier Transform Infrared Spectra (FTIR), Thermal analysis (DSC) and X-ray diffraction (XRD) analysis. Simultaneously water absorbency, swelling kinetics and water retention abilities of this prepared superabsorbent polymeric composites were also investigated systematically.     

Preparation and swelling properties of semi‐IPN hydrogels based on chitosan‐g‐poly(acrylic acid) and phosphorylated polyvinyl alcohol

The phosphorylated poly(vinyl alcohol) (P‐PVA) samples with various substitution degrees were prepared through the esterification reaction of PVA and phosphoric acid. By using chitosan (CTS), acrylic acid (AA) and P‐PVA as raw materials, ammonium persulphate (APS) as an initiator and N,N‐methylenebisacrylamide as a crosslinker, the CTS‐g‐PAA/P‐PVA semi‐interpenetrated polymer network (IPN) ssuperabsorbent hydrogel was prepared in aqueous solution by the graft copolymerization of CTS and AA and followed by an interpenetrating and crosslinking of P‐PVA chains. The hydrogel was characterized by Fourier transform infrared (FTIR), scanning electron microscopy (SEM), and differential scanning calorimetry (DSC) techniques, and the influence of reaction variables, such as the substitution degree and content of P‐PVA on water absorbency were also investigated. FTIR and DSC results confirmed that PAA had been grafted onto CTS backbone and revealed the existence of phase separation and the formation of semi‐IPN network structure. SEM observations indicate that the incorporation of P‐PVA induced highly porous structure, and P‐PVA was uniformly dispersed in the polymeric network. Swelling results showed that CTS‐g‐PAA/P‐PVA semi‐IPN superabsorbent hydrogel exhibited improved swelling capability (421 g·g^?1 in distilled water and 55 g·g^?1 in 0.9 wt % NaCl solution) and swelling rate compared with CTS‐g‐PAA/PVA hydrogel (301 g·g^?1 in distilled water and 47 g·g^?1 in 0.9 wt % NaCl solution) due to the phosphorylation of PVA. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Poly(acrylic acid)–poly(vinyl alcohol) semi- and interpenetrating polymer network pervaporation membranes

A series of poly(acrylic acid) (PAA)–poly(vinyl alcoho) (PVA) semiinterpenetrating (SIPN) and interpenetrating (IPN) polymer network membranes were prepared by crosslinking PVA alone or by crosslinking both PVA and PAA. Glutaraldeyde and ethylene glycol were used as crosslinking agents for the PVA and PAA networks, respectively. The presence of PAA increases the permeability of the membranes while the presence of PVA improves their mechanical and film-forming properties. The mechanical properties of the membranes were investigated via tensile testing. These hydrophilic membranes are permselective to water from ethanol–water mixture and to ethanol from ethanol–benzene mixtures. The IPN membranes were employed for the former mixtures and the SPIN membranes for the latter, because the IPN ones provided too low permeation rates. The permeation rates and seperation factors were determined as functions of the IPN or SIPN composition, feed composition, and temperature. For the azeotropic ethanol–water mixture (95 wt % ethanol), the separation factor and permeation rate at 50°C of the PAA-PVA IPN membrane, containing 50 wt % PAA, were 50 and 260 g/m²h, respectively. For the ethanol–benzene mixture, the PAA–PVA SIPN membranes had separation factors between 1.4 and 1200 and permeation rates between 6 and 550 g/m²h, respectively, depending on the feed composition and temperature. © 1996 John Wiley & Sons, Inc.     

Cellulose–poly(acrylamide or acrylic acid) interpenetrating polymer network membranes for the pervaporation of water–ethanol mixtures

A new type of interpenetrating polymer network (IPN) pervaporation membranes based on cellulose and synthetic polymers was developed. They were prepared by free-radical polymerization of acrylamide or acrylic acid in the presence (or absence) of the crosslinking agent (allyldextran or N,N′-methylenebisacrylamide) within cellophane films swollen in the reaction mixture. The swelling behavior of these membranes in water–ethanol solutions and their separation characteristics were investigated depending on the polyacrylamide (PAAm) or poly(acrylic acid) (PAA) content in the IPN (C_p) and for ionic cellulose–PAA membranes depending on the degree of neutralization of carboxylic groups and on the type of counterions. IPN membranes were selective over a wide range of ethanol concentration in the feed. The separation factor (α) and the permeation rate (P) significantly improved with increasing C_p in IPN membranes, especially for the cellulose–PAA(K⁺ form) membranes (for 86% EtOH feed at 50°C, and α and P values reached 1500 and 1.6 kg/m² h, respectively). The results for ionic and nonionic IPN membranes were compared. The separation characteristics of membranes were in good correlation with their swelling behavior. The α values of the membranes depended on the affinity of the IPN polymer chains functional groups for water. © 1998 John Wiley & Sons, Inc. J Appl Polym Sci 69: 761–769, 1998     

Electrical sensitivity behavior of a hydrogel composed of polymethacrylic acid/poly(vinyl alcohol)

An interpenetrating polymer network (IPN) composed of polymethacrylic acid (PMAA) and poly(vinyl alcohol) (PVA) was prepared and exhibited electrical sensitivity behavior. The swelling behavior of the PMAA/PVA IPN hydrogel was studied by immersion of the gel in aqueous NaCl solutions at various concentrations and pH values. The stimuli response of the PMAA/PVA IPN hydrogel in electric fields was also investigated. When swollen IPN hydrogel was placed between a pair of electrodes, the PMAA/PVA IPN hydrogel exhibited bending behavior upon the application of an electric field. The PMAA/PVA IPN hydrogel also showed stepwise bending behavior depending on the electric stimulus. Also, for biomedical applications, the bending behavior of PMAA/PVA IPN hydrogel in Hank's solution at pH 7.4 was studied. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 91:3613–3617, 2004