壳聚糖接枝聚丙烯酰胺水凝胶的制备及性质研究

通过接枝共聚反应制备了几种壳聚糖接枝聚丙烯酰胺水凝胶，其中过硫酸钾为自由基引发剂，亚甲基双丙烯酰胺或甲醛为交联剂，并研究了实验因素，如交联剂浓度和单体比率对水凝胶溶胀能力的影响。实验表明水凝胶具有离子强度、pH值和温度敏感性。这种可随外界因素响应及“开关”的性质，使此类智能水凝胶有望成为生物制品载体，例如药物载体。     

温度/pH敏感型壳聚糖水凝胶的制备及其性能

以天然可降解高分子壳聚糖为载体,选择温度敏感单体N-异丙基丙烯酰胺以及pH敏感单体2-丙烯酰胺基-2-甲基丙磺酸,以偶氮二异丁腈为引发剂,N,N-亚甲基双丙烯酰胺为交联剂,通过自由基接枝共聚反应制备壳聚糖水凝胶。通过红外(IR)、扫描电镜(SEM)对其结构及形貌进行了表征,并探讨了影响水凝胶溶胀率的因素。结果表明,当单体配比NIPAM∶AMPS为6∶4、引发剂用量为单体总质量4%、交联剂用量为单体总质量的4%、反应温度为45℃形成的水凝胶在水中溶胀率可达95%左右。该水凝胶具有一定的温度和pH敏感性,预计在药物控释、组织工程、抗凝血材料等领域拥有广阔的应用前景。     

温度/pH敏感型壳聚糖水凝胶的制备及其性能

以天然可降解高分子壳聚糖为载体,选择温度敏感单体N-异丙基丙烯酰胺以及pH敏感单体2-丙烯酰胺基-2-甲基丙磺酸,以偶氮二异丁腈为引发剂,N,N-亚甲基双丙烯酰胺为交联剂,通过自由基接枝共聚反应制备壳聚糖水凝胶。通过红外(IR)、扫描电镜(SEM)对其结构及形貌进行了表征,并探讨了影响水凝胶溶胀率的因素。结果表明,当单体配比NIPAM∶AMPS为6∶4、引发剂用量为单体总质量4%、交联剂用量为单体总质量的4%、反应温度为45℃形成的水凝胶在水中溶胀率可达95%左右。该水凝胶具有一定的温度和pH敏感性,预计在药物控释、组织工程、抗凝血材料等领域拥有广阔的应用前景。     

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...     

P(AAm-co-AA)/Ag复合材料制备及表征

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,采用交联共聚方法合成了具有pH敏感性的半互穿网络丙烯酰胺-co-丙烯酸水凝胶P(AAm-co-AA),利用水凝胶网络结构作为纳米反应器,自组装制备了纳米复合水凝胶P(AAm-co-AA)/Ag。水凝胶的溶胀行为研究表明,AAm与AA的质量比影响P(AAm-co-AA)/Ag水凝胶平衡溶胀率。     

温度、pH敏感性共聚物(MA-co-NIPMAM)水凝胶的制备及性能研究

以N,N′-亚甲基双丙烯酰胺(MBA)为交联剂,以甲基丙烯酸(MA)和N-异丙基甲基丙烯酰胺(NIPMAM)作为聚合单体合成具有温度及p H双重敏感性的水凝胶。研究了MBA的用量与水凝胶溶胀过程的影响。在25℃和55℃下分别研究水凝胶在酸性和碱性条件下的去溶胀动力学和再溶胀动力学过程。     

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。     

温度与pH敏感P(NIPAM-co-MAA)水凝胶的制备及性能研究

室温条件下,以安息香双甲醚作为光引发剂、N,N-亚甲基双丙烯酰胺为交联剂,在乙醇溶液中,采用紫外光照聚合的方法,合成了透明均质的聚(N-异丙基丙烯酰胺-co-甲基丙烯酸)共聚物水凝胶。用红外光谱和扫描电镜分析了水凝胶的结构,通过测定水凝胶的溶胀率和退涨率考察了单体、引发剂及交联剂用量对其性能的影响。通过p H敏感性测定,发现该共聚凝胶为阴离子型p H敏感水凝胶。在弱碱性溶液中有最高的溶胀率。     

P(AM-AMPS)水凝胶的制备与性能研究

以丙烯酰胺(AM)和2-丙烯酰胺基-2-甲基丙磺酸(AMPS)为原料,N,N’-亚甲基双丙烯酰胺(NMBA)为交联剂,过硫酸铵((NH)S0)和亚硫酸氢钠(NaHSO)为引42283发剂,采用静置水溶液法合成PAM-AMPS水凝胶。讨论了引发剂、交联剂、单体配比、单体浓度、pH值等因素对产物吸水性能的影响。结果表明,合成的水凝胶具有一定的吸水性、吸盐性。()     

新型聚丙烯酰胺凝胶制备、表征及强度和溶胀性能研究

以丙烯酰胺(AM)为单体,对二乙烯苯(p-DVB)为交联剂,过硫酸铵(APS)为引发剂,采用自由基溶液聚合的方法合成了交联聚丙烯酰胺凝胶。利用红外对其结构进行了表征;测定了水凝胶的力学性能和溶胀特性,并分别与目前广泛应用的BIS交联的水凝胶进行对比。研究表明,以含苯环结构的p-DVB代替BIS作为交联剂能够提高交联聚丙烯酰胺凝胶的力学强度和溶胀性能,当单体浓度为15%,交联剂浓度为1%时,p-DVB交联的水凝胶压缩强度接近1 MPa,25℃时的平衡溶胀比达到40 g/g。     

Swelling behavior and determination of diffusion characteristics of acrylamide–acrylic acid hydrogels

In this study, a random copolymer of acylamide and acrylic acid [poly(AAm‐co‐AA)] was prepared by a redox copolymerization method of their aqueous solutions. The effects of initial AAm/AA mole ratio, PEG 4000 content, and N,N′‐methylenebisacrylamide concentration on swelling behavior were investigated in water. Average molecular weights between crosslinks, percentage swelling, swelling equilibrium values, and diffusion/swelling characteristics (i.e., the structure of network constant, the type of diffusion, the initial swelling rate, swelling rate constant) were evaluated for every hydrogel systems. The hydrogels showed mass swelling capabilities in the range 789–1040% (for AAm/AA hydrogels), 769–930% (for AAm/AA hydrogels in the presence of PEG 4000), and 716–1040% (for AAm/AA hydrogels containing different concentrations of the crosslinker). The swelling capabilities of the hydrogels decreased with the increasing AA, PEG 4000, and crosslinker concentrations. The diffusion of water into AAm/AA hydrogels was found to be a non‐Fickian type. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 91: 1289–1293, 2004     

Swelling characterization of poly (acrylamide-<Emphasis Type="Italic">co</Emphasis>-<Emphasis Type="Italic">N</Emphasis>-vinylimidazole) hydrogels crosslinked by TMPTA and semi-IPN’s with PEG

In this study, a novel semi-interpenetrating network (semi-IPN’s) hydrogel, composed of acrylamide (AAm) with N-vinylimidazole (NVI) as comonomer, with poly (ethylene glycol)(PEG) and a multifunctional crosslinker such as trimethylolpropane triacrylate (TMPTA) was prepared. Highly swollen poly (AAm/NVI) hydrogels and semi-IPN’s were synthesized by free radical solution polymerization. Swelling experiments were performed in water at 25°C, gravimetrically. The influence of NVI and PEG content in hydrogels were examined. Poly (AAm/NVI) and poly (AAm/NVI/PEG) hydrogels showed large extents of swelling in aqueous media the swelling being highly dependent on the chemical composition of the hydrogels. Swelling ratio of poly (AAm/NVI) hydrogels and poly (AAm/NVI/PEG) hydrogels was shown 7.16–39.85. Diffusion behavior was investigated. Water diffusion into hydrogels was found to be non-Fickian in character. This study has given the quantitative information on the swelling characteristic of poly (AAm/NVI) hydrogel and semi-IPN’s as water absorbent in many potential applications.     

Swelling behavior and diffusion studies of high‐water‐retaining acrylamide/potassium methacrylate hydrogels

Poly(acrylamide‐co‐potassium methacrylate) hydrogels were prepared by free‐radical simultaneous polymerization with aqueous solutions of acrylamide (AAm) and potassium methacrylate (KMA) with a redox initiator. The copolymerization was performed with eight different compositions of KMA at a fixed concentration of oil‐soluble crosslinkers, including 1,4‐butanediol diacrylate and ethylene glycol dimethacrylate (EGDMA). For every composition of AAm/KMA copolymer, the percentage swelling, swelling equilibrium, and diffusion characteristics were investigated. The copolymers were further studied for deswelling properties. The power law relationships of the hydrogels were evaluated for variation in terms of saline concentration. The AAm/KMA copolymers were confirmed by IR spectroscopy. Thermal studies of hydrogels were performed with differential scanning calorimetry and thermogravimetric analysis. EGDMA was found to be a better crosslinker for obtaining higher swelling and deswelling properties for the AAm/KMA hydrogels. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 96: 1153–1164, 2005     

Preliminary swelling and dye sorption studies of acrylamide/4-styrenesulfonic acid sodium salt copolymers and semi-interpenetrating polymer networks composed of gelatin and/or PEG

Semi-IPN hydrogels based gelatin (GEL) and/or poly (ethylene glycol) (PEG) were prepared with acrylamide (AAm) and 4-styrenesulfonic acid sodium salt, (SSS) as a water adsorbent for cationic dye (methyl violet, MV) sorption. For this, chemically crosslinked copolymer of AAm/SSS copolymer with GEL and/or PEG were prepared by polymerization of aqueous solution of AAm and SSS using ammonium persulfate (APS)/N,N,N′,N′-tetramethylethylenediamine (TEMED) as redox initiating pair in presence of poly(ethylene glycol)diacrylate (PEGDA) as crosslinker. FT-IR analysis was used to identify the presence of different repeating units in the semi-IPNs. Surface morphology was characterized by scanning electron microscopy (SEM). Some swelling and diffusion characteristics were calculated for different semi-IPNs and hydrogels prepared under various formulations. Water uptake, and dye sorption properties of the crosslinked polymeric systems such as AAm/SSS, AAm/GEL/SSS, AAm/PEG/SSS and AAm/GEL/PEG/SSS hydrogel systems were investigated as a function of chemical composition of the hydrogels. MV have used in sorption studies.     

Behavior of semi IPN hydrogels composed of PEG and AAm/SMA copolymers in swelling and uptake of Janus Green B from aqueous solutions

Semi-interpenetrating polymer network (semi IPN) hydrogels of poly(ethylene glycol; PEG) were prepared as a water adsorbent for dye (Janus Green B) sorption. For this, PEG and copolymer of acrylamide/sodium methacrylate (AAm/SMA) were prepared by polymerization of aqueous solution of acrylamide (AAm), sodium methacrylate (SMA) using ammonium persulfate (APS)/N,N,N′,N′-tetramethylethylenediamine (TEMED) as redox initiating pair in presence of PEG and poly(ethylene glycol)dimethacrylate (PEGDMA) as crosslinker. FTIR spectroscopy was used to identify the presence of different repeating units in the semi IPNs. Some swelling and diffusion characteristics were calculated for different semi IPNs and hydrogels prepared under various formulations. Water uptake and dye sorption properties of AAm/SMA hydrogels and AAm/SMA/PEG semi IPNs were investigated as a function of chemical composition of the hydrogels. Janus Green B have used in sorption studies. © 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

Dual pH‐ and temperature‐responsive hydrogels with extraordinary swelling/deswelling behavior and enhanced mechanical performances

pH‐ and temperature‐responsive semi‐interpenetrating nanocomposite hydrogels (NC hydrogels) were prepared with surface‐functionalized graphene oxide (GO) as the crosslinker, N‐isopropylacrylamide (NIPAM) as the monomer, and chitosan (CS) as an additive. The effects of 3‐(trimethoxysilyl)propylmethacrylate‐modified GO sheets and CS content on various physical properties were investigated. Results show that PNIPAM/CS/GO hydrogels undergo a large volumetric change in response to temperature. Swelling ratios of PNIPAM/CS/GO hydrogels are much larger than those of the conventional organically crosslinked PNIPAM hydrogels. The deswelling test indicates that the deswelling rate was greatly enhanced by incorporating CS into the hydrogel network and using the surface‐functionalized GO as the crosslinker. The pH‐sensitivity of PNIPAM/CS/GO hydrogels is evident below their volume phase transition temperature. Moreover, the PNIPAM/CS/GO hydrogels have a much better mechanical property compared with traditional hydrogels even in a high water content of 90%. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 41530.     

Swelling and Diffusion Properties of Poly(acrylamide-co-maleic acid) Hydrogels: A Study with Different Crosslinking Agents

Crosslinked hydrogels comprising acrylamide (AAm) and maleic acid (MA) were synthesized by free radical polymerization in presence of a crosslinker using ammonium persulfate (APS) and N,N,N¹,N¹-tetramethylethylenediamine (TMEDA) as initiator and activator, respectively. The crosslinked hydrogel formation was confirmed by IR analysis. The swelling/de-swelling characteristics were studied in detail for crosslinked poly(acrylamide-co-maleic acid) [poly(AAM-co-MA)] hydrogels containing different amounts of maleic acid. Four different crosslinkers such as 1,2-ethyleneglycol dimethacrylate (EGDMA), 1,4-butanediol diacrylate (BDDA), 1,6-hexanediol diacrylate (HDDA), and diallyl phthalate (DP) were utilized to study their influence on the swelling behavior of the hydrogels. The effect of reaction parameters such as the concentration of crosslinker and initiator on swelling capacity of the crosslinked poly(AAm-co-MA) hydrogels was also investigated. Further, the influence of various salts, simulated biological fluids, and pH solutions on the swelling pattern of hydrogels was studied extensively. Phase separation morphology of crosslinked hydrogels was also studied by differential scanning calorimetry. The morphology of crosslinked hydrogels were revealed using scanning electron microscopy (SEM).     

Trititanate‐nanosheet incorporated hydrogels: Self‐initiated photopolymerization and application in photodegradation of methylene violet

Exposing the aqueous mixtures of acrylamide (AAm) monomers and exfoliated trititanate nanosheets (TiNs) to ultraviolet light achieved nanocomposite hydrogels TiNs–PAAm in a facile one‐step synthetic route. The incorporated semiconductor TiNs functioned as a photocatalytic crosslinker, initiating the in situ photopolymerization of monomers and hydrogen‐bonding crosslinking with the polymeric networks to form nanocomposite hydrogels. The resultant hydrogels exhibited good absorption behaviors of methylene violet (MV), and the hydrogel prepared from an AAm/TiNs ratio of 2.46 × 10² g/g exhibited a maximum uptake of 8.4 g MV solution for 1 g. The immobilized TiNs retained high photocatalytic activity in the recyclable photodegradation of MV. It indicated the nanocomposite hydrogels may be considered as a good candidate in wastewater treatment. POLYM. COMPOS., 37:2811–2819, 2016. © 2015 Society of Plastics Engineers     

Environmentally sensitive hydrogels: N‐isopropyl acrylamide/Acrylamide/ Mono‐, Di‐, Tricarboxylic acid crosslinked polymers

Environmentally sensitive hydrogels responsive to various stimuli such as temperature, pH, ionic strength of the medium and the solvent were prepared by using N‐isopropyl acrylamide (NIPAM), acrylamide (AAm) and monomers that have various number of carboxylic acid (XA) functionality using N,N′‐methylene bisacrylamide (Bis) as crosslinker. Hydrogels were prepared via free radical polymerization reaction in aqueous solution. P(NIPAAm‐co‐AAm) and p(NIPAAm‐co‐AAm)/XA hydrogels that contain monoprotic crotonic acid (CA) exhibit a lover critical solution temperature (LCST) at 28°C, whereas p(NIPAAm‐co‐AAm)/IA (IA:itaconic acid), and P(NIPAAm‐co‐AAm)/ACA (ACA:acotonic acid) hydrogels exhibit a lover critical solution temperature at 30.7°C and 34.4°C, respectively. Spectroscopic and thermal analyses were performed for the structural and thermal characterizations of the prepared hydrogel. The swelling experiments as equilibrium swelling percentages by gravimetrically were carried out in different solvents, at different solutions temperature, pH, and ionic strengths to determine their effects on swelling characteristic of hydrogels. POLYM. ENG. SCI., 55:843–851, 2015. © 2014 Society of Plastics Engineers