AM与HEMA共聚制备水凝胶接触镜材料及其溶胀性能

采用丙烯酰胺(AM)与甲基丙烯酸β-羟乙酯(HEMA)进行本体共聚制备水凝胶接触镜材料,研究了水凝胶的溶胀性能及其温度和pH值敏感性。结果表明,引发剂过氧化苯甲酰(BPO)用量为反应单体总质量的0.3%、反应温度80℃,产物溶胀之后为无色透明的玻璃状水凝胶;共聚物水凝胶具有较好的pH值敏感性,水凝胶在酸性溶液中溶胀,在碱性溶液中收缩:含有AM的水凝胶,其pH值敏感性较大:随AM的含量增大,共聚物水凝胶的溶胀速度和饱和含水量增大,随温度升高,水凝胶的饱和含水量下降,共聚物水凝胶中AM的含量对其温度敏感性无显著影响:SEM照片显示,AM与HEMA共聚物存在均匀的纤维状结构,并且共聚物中AM的含量越大,这种纤维状结构越大、越明显。     

聚N-丙烯酰基甘氨酸水凝胶的合成及溶胀性能

以N-丙烯酰基甘氨酸（Acgly）为单体、过硫酸铵（APS）为引发剂、亚甲基双丙烯酰胺（MBA）为交联剂,通过溶液自由基聚合得到含有不同交联剂用量的水凝胶,并进行红外光谱表征．实验中对合成的水凝胶在不同pH条件下的平衡溶胀比和溶胀收缩可逆性进行测试．结果表明：随着交联剂质量分数从0.5％增大至7％,水凝胶外观由无色透明变为白色不透明,同时水凝胶由软变硬,弹性变小,硬度增加;在2．8〈pH〈3．8范围内水凝胶的平衡溶胀比随溶液的pH增大迅速增大,水凝胶表现出较好的pH敏感性;在pH=1．0和pH=6．8条件下的水凝胶具有很好的收缩溶胀可逆性．     

pH-温度双重敏感性水凝胶的制备及溶胀性能研究

制备具有pH及温度双重敏感性水凝胶。通过自由基聚合反应制备出NIPAM-co-PMAA水凝胶材料。考察不同单体甲基丙烯酸(MAA)和N-异丙基丙烯酰胺(NIPA)配比对pH和温度的响应能力,探究其溶胀性能。结果表明,不同配比的水凝胶具有双重敏感性。NIPA含量不同时,对于LSCT温度有影响,MAA含量不同时,在酸性条件下溶胀率较大。结论,NIPAM-co-PMAA水凝胶有望成为药物载体。     

P（MA—AA）／PEG水凝胶的制备与性能研究

合成了马来酸酐-丙烯酸共聚物,并与长链分子聚乙二醇交联反应制备了马来酸酐-丙烯酸共聚物／聚乙二醇水凝胶。通过红外光谱对聚合物、水凝胶结构进行了表征,测试了不同pH值下水凝胶的溶胀度以及水凝胶在酸碱条件发生变化时的溶胀速率。研究结果表明,马来酸酐-丙烯酸共聚物／聚乙二醇水凝胶具有较强的吸水溶胀能力,并且对pH值极为敏感：交联剂含量7％的凝胶在pH=10时SR=62657％、pH=2时SR=825％,酸碱条件下具有近百倍的溶胀度变化;并且在pH发生变化时P（MA-AA）／PEG凝胶具有快速的响应速率：由pH=2溶液中转移至pH=10溶液中20min即可溶胀完全,而由pH=10溶液中转移至pH=2溶液中10min即可完全收缩。     

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。     

P(MAA-co-MMA)水凝胶的合成及其pH响应性

以甲基丙烯酸(MAA)和甲基丙烯酸甲酯(MMA)为单体、N,N-亚甲基双丙烯酰胺(BIS)为交联剂、偶氮二异丁腈(AIBN)为引发剂,用溶液聚合制得P(MAA-co-MMA)水凝胶,研究不同pH缓冲液中该凝胶的响应性。结果表明,x(MMA)=5%投料量的P(MAA-co-MMA)凝胶在220℃以下处于高弹态,冻干处理的凝胶具有良好的pH响应性,即随着环境pH的增大,凝胶的平衡溶胀比也增大。     

基于动态共价键的pH响应自修复水凝胶的制备与评价

以α-甲基丙烯酸(MAA)和2-丙烯酰胺-2-甲基丙磺酸(AMPS)的共聚物P(MAA/AMPS)及聚乙烯醇(PVA)为单体、十水合四硼酸钠为交联剂合成了P(MAA/AMPS)-PVA二重互穿网络的pH响应水凝胶.通过SEM、FTIR、GPC、TGA-DTG和流变仪等表征了水凝胶的表面形貌和化学状态;测定了水凝胶的溶胀性﹑pH响应性﹑自修复性和流变性.结果表明,水凝胶形成了稳定的互穿网络结构且具有pH敏感性、自修复性;PVA羟基与硼酸根离子形成的共价配位硼酸酯键使水凝胶具备自修复性并受介质酸碱性的控制;力学性能测定结果显示,自修复水凝胶(SB用量为2.5％,水凝胶溶胀度为4)拉伸强度668 kPa,断裂伸长率可达665％,修复效率可达81％.     

pH敏感P(MAA-co-BMA)水凝胶的溶胀行为

以甲基丙烯酸(MAA)和甲基丙烯酸丁酯(BMA)为共聚单体、N,N-亚甲基双丙烯酰胺为交联剂、偶氮二异丁腈为引发剂,用溶液聚合法合成P(MAA-co-BMA)水凝胶,研究其吸水溶胀性和pH敏感性。结果表明,BMA投料为摩尔分数5%的共聚水凝胶在211℃以下处于高弹态,其吸水溶胀比可达52;该凝胶烘干和冻干处理后的pH敏感性都很好,即平衡溶胀比随着pH增大而增大;而冻干凝胶因具有规律的大孔结构,在不同pH溶液中的平衡溶胀比差异更大。     

pH响应性P(AA-co-C8PhEO10Mac) 水凝胶的制备及其对L-抗坏血酸的控释性能

采用自由基交联共聚法合成了具有pH敏感性的水凝胶聚丙烯酸-co-甲基丙烯酸辛基酚聚氧乙烯醚酯〔P(AA-co-C8PhEO10Mac)〕,考察了不同单体配比的水凝胶在不同pH的缓冲溶液中的溶胀性、溶胀动力学和退溶胀动力学。通过浸泡法在水凝胶中载入L-抗坏血酸,初步研究了模拟胃肠液中,凝胶对L-抗坏血酸的释放行为。结果表明,凝胶兼具快速的溶胀和退溶胀速率,良好的pH敏感性等特征;载药凝胶在模拟肠液(SIF,pH=7.4)中对药物的累计释放率明显大于在模拟胃液(SGF,pH=1.4)中的累计释放率,增大丙烯酸的用量使累计释放率先升高后降低。采用滤纸片法研究了甲基丙烯酸辛基酚聚氧乙烯醚酯(C8PhEO10Mac)对大肠杆菌、酿酒酵母的抑制作用,结果显示,在10～50 mmol/L的测试浓度水平,C8PhEO10Mac对二者均无明显的抑制作用。     

聚(甲基丙烯酸/丙烯酰胺)pH敏感微球的制备及性能的研究

以单体丙烯酰胺(AM)、甲基丙烯酸(MAA)为原料,N,N’-亚甲基双丙烯酰胺(MBA)为交联剂,偶氮二异丁腈(AIBN)为引发剂,在无水乙醇溶液中,60℃时通过沉淀聚合的方法制备出一系列的聚甲基丙烯酸/丙烯酰P(MAA/AM)微球。实验结果表明,成功的制备700～1 100 nm粒径范围内的单分散的微球;初步实现了对单分散的微球粒径大小及分布情况的控制设计。此外,微球具有良好的pH敏感性,此性能与MAA的解离常数有关;通过对环境pH值的调节可以迅速控制微球自身体积的收缩与溶胀。     

Preparation and swelling of polymeric hydrogels

Hydrogel polymers find extensive biomedical applications combining the properties of hydrophilic and crosslinked materials. In this work, poly(methacrylic acid) hydrogels were prepared by the copolymerization of methacrylic acid with varying amounts of 1,4-butanediol dimethacrylate. The polymerization reaction was followed by viscometric measurements and the swelling properties of the samples prepared were also investigated. Alkaline treatment of the hydrogels was performed, to define the changes induced. Finally, a correlation between swelling data, derived from loosely crosslinked samples, led to the determination of the interaction parameter of the system poly(methacrylic acid)–water.     

Investigation of swelling and controlled-release behaviors of hydrophobically modified poly(methacrylic acid) hydrogels

Using hydrophobic acrylic acid-2-ethylhexyl ester (AAEHE) as a comonomer of methacrylic acid (MAA), a series of hydrophobically modified (HM) poly(methacrylic acid) (PMAA) (HMPMAA) hydrogels were prepared by UV solution copolymerization and studied as controlled-release matrices. The result indicates that swelling degree of the HMPMAA hydrogels can sensitively respond to change in pH. However, the presence of hydrophobic AAEHE segments influences swelling kinetics of PMAA hydrogel evidently. Using p-hydroxyanisole (PHAS) as a model molecule, controlled-release behaviors of the HMPMAA hydrogels were investigated. It is found that the presence of hydrophobic AAEHE segments can markedly slow down the release rate of PHAS from PMAA-based hydrogels regardless of pH 1.4 or 7.4.     

智能型聚甲基丙烯酸凝胶的合成与表征

以甲基丙烯酸(MAA)为单体,过硫酸钾(KPS)为引发剂,无机纳米粒子Laponite或者N,N'-亚甲基双丙烯酰胺(BIS)为交联剂,通过原位自由基聚合的方法分别合成了纳米复合聚甲基丙烯酸凝胶和传统型聚甲基丙烯酸凝胶,并利用红外、流变、溶胀性能测试、剥离强度测试等手段对凝胶的性能进行了表征。比较了在不同单体(MAA)含量、体系pH值下,Laponite含量和BIS含量对物理交联法和化学交联法制备的凝胶的交联密度的影响,以及两种凝胶溶胀度随溶液pH值以及温度的变化关系。研究表明:增加单体MAA的含量、增加交联剂Laponite或BIS的含量,以及降低体系的pH值有利于凝胶网状结构的形成。化学交联的传统型聚甲基丙烯酸凝胶具有明显的pH敏感性和温度敏感性,而物理交联的纳米复合聚甲基丙烯酸凝胶具有良好的粘结性能。     

Radiation Synthesis of Carboxymethyl Cellulose Hydrogels for Removal of Organic Contaminants from Its Aqueous Solution

Preparation of hydrogels based on carboxymethyl cellulose (CMC) using direct radiation grafting technique for removal of organic contaminant such as 4‐chlorophenol and 2,4‐dichlorophenoxyacetic acid (2,4‐D) was carried out. The prepared hydrogels which are composed of individual radiation grafting of methacrylic acid onto CMC to form poly(CMC/MAA) the other hydrogel composed of binary acrylamide/methacrylic acid grafted onto CMC to form poly(CMC/MAA:AAm) hydrogels. The two selected composition poly(CMC/MAA:AAm) (1/60:40 wt%) poly(CMC/MAA) (1:20) wt% hydrogels due to its high chelating properties obtained from our previous work by the same authors. The properties of the selected two prepared hydrogels were evaluated by using different analytical tools such as Fourier transform infrared (FTIR), X‐ray diffraction (XRD), and thermogravimetric analysis (TGA). The gel (%) and the swelling behavior of poly(CMC/MAA:AAm) is higher than poly(CMC/MAAc) hydrogel. It is found that the adsorption capacity of poly(CMC/MAA) hydrogel (1:20 wt%) toward 4‐chlorophenol and 2,4 dichlorophenoxy acetic acid was higher than that of poly(CMC/MAA:AAm) (1/60:40 wt%) hydrogel. Also The obtained results showed that the adsorption capacity of both poly(CMC/MAA:AAm) (1/60:40 wt%) and poly(CMC/MAA) (1:20) wt% hydrogels toward 2,4 dichlorophenoxy acetic acid was higher than of 4‐chlorophenol. J. VINYL ADDIT. TECHNOL., 26:362–369, 2020. © 2019 Society of Plastics Engineers     

Preparation of pH‐sensitive poly(vinyl alcohol‐g‐methacrylic acid) and poly(vinyl alcohol‐g‐acrylic acid) hydrogels by gamma ray irradiation and their insulin release behavior

A series of pH‐responsive hydrogels were studied as potential drug carriers for the protection of insulin from the acidic environment of the stomach before releasing in the small intestine. Hydrogels based on poly(vinyl alcohol) networks grafted with acrylic acid or methacrylic acid were prepared by a two‐step process. Poly(vinyl alcohol) hydrogels were prepared by gamma ray irradiation (50 kGy) and then followed by grafting either acrylic acid or methacrylic acid onto these poly(vinyl alcohol) hydrogels with subsequent irradiation (5–20 kGy). These graft hydrogels showed pH‐sensitive swelling behavior and were used as carriers for the controlled release of insulin. The in vitro release of insulin was observed for the insulin‐loaded hydrogels in a simulated intestinal fluid (pH 6.8) but not in a simulated gastric fluid (pH 1.2). The release behavior of insulin in vivo in a rat model confirmed the effectiveness of the oral delivery of insulin to control the level of glucose. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 91: 636–643, 2004     

Enhanced adsorption properties of interpenetrating polymer network hydrogels for heavy metal ion removal

In this study, sequential interpenetrating polymer network (IPN) hydrogels based on poly(polyethylene glycol diacrylate) poly(PEGDA) and poly(methacrylic acid) (PMAA) were prepared with enhanced adsorption properties for heavy metal ion removal. The swelling behavior and mechanical property of the IPN hydrogels were characterized. It was found that swelling ratio increased, and mechanical strength decreased with the PMAA content in the IPN. The IPN hydrogels were used to remove heavy metal ions from aqueous solution under the non-competitive condition. The effects of pH values of the feed solution at the range of 3–5 and PMAA content in the IPN on the adsorption capacity were investigated. The results indicated that the adsorption capacity of the IPN hydrogels increased with the pH values and PMAA content in the IPN. Furthermore, the synergistic complexation of metal ions with two polymer networks in the IPN was found in the adsorption studies. Regeneration studies suggested that metal rebinding capacity of the IPN hydrogels did not change significantly through repeated applications compared with the first run. It was concluded that the poly(PEGDA)/PMAA hydrogels could be used as fast-responsive, high capacity, and renewable sorbent materials in heavy metal removing processes.     

Synthesis and characterization of an interpenetrating polymer network composed of poly(methacrylic acid) and poly(vinyl alcohol)

Temperature and pH‐responsive interpenetrating polymer network (IPN) hydrogels, constructed with poly(methacrylic acid) (PMAA) and poly(vinyl alcohol) (PVA), by a sequential IPN method, were studied. The characterization of IPN hydrogels was investigated by Fourier‐transform infrared spectroscopy, differential scanning calorimetry (DSC) and swelling under various conditions. The IPN hydrogels exhibited relatively high swelling ratios, in the range 230–380 %, at 25 °C. The swelling ratios of the PMAA/PVA IPN hydrogels were pH and temperature dependent. DSC was used for the quantitative determination of the amounts of freezing and non‐freezing water. The amount of free water increased with increasing PMAA content in the IPN hydrogels. Copyright © 2004 Society of Chemical Industry     

Radiation synthesis of poly(N‐vinylpyrrolidone‐co‐methacrylic acid) hydrogels and their usability in uranyl ion adsorption

In this study, N‐vinylpyrrolidone(VP)/methacrylic acid (MAA) mixtures have been prepared at three different mole percents which the methacrylic acid composition around 5, 10, and 15%. Poly(N‐vinylpyrrolidone‐co‐methacrylicacid) P(VP/MAA) hydrogels irradiated at 3.4 kGy have been used for swelling and diffusion studies in water and uranyl ion solutions. The influence of dose, pH, relative amounts of monomers in MAA/VP monomer mixtures on the swelling properties have been investigated. P(VP/MAA) hydrogels were swollen in distilled water at pH 7.0. P(VP/MAA)1 hydrogel containing 36% (mole percent) methacrylic acid showed the maximum percent swelling in water. Adsorption isotherms were constructed for uranyl ions and P(VP/MAA) hydrogel systems. It has been found that P(VP/MAA) hydrogels have very high uptake of the uranyl ions succesfully in water containing uranyl ions. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Swelling Properties of Chemically Crosslinked Poly(acrylamide-co-maleic acid) Hydrogels

ABSTRACT

Chemically crosslinked poly(acrylamide-co-maleic acid) [poly(AAm-co-MA)] hydrogels were prepared by simultaneous free radical copolymerization of acrylamide (AAm) with maleic acid (MA) in presence of di or tri functional crosslinking agents using ammonium persulfate-N,N,N′,N′-tetramethylethylenediamine (APS-TMEDA) redox-initiating system. The poly(AAm-co-MA) hydrogels formation was confirmed by IR studies. The influence of crosslinkers such as N,N′-methylene-bis-acrylamide (MBA) and 2,4,6-triallyloxy-1,3,5-triazine (TATA) on swelling/de-swelling characteristics were studied in detail for poly(AAm-co-MA) hydrogels containing different amounts of maleic acid. The present investigation also deals with the influence of concentration of crosslinker and initiator on the swelling behavior of poly(AAM-co-MA) hydrogels. The effect of various salts on swelling capacity was studied. In addition, the effect of simulated biological fluids and pH solutions on the swelling of hydrogels was also studied in detail.     

A fast pH-responsive IPN hydrogel: Synthesis and controlled drug delivery

A series of fast pH-responsive silk sericin (SS)/poly(methacrylic acid) (PMAA) IPN hydrogels were prepared by the simultaneous-IPN method. The structure of the resultant IPN hydrogels was characterized by fourier transform infrared spectroscopy (FTIR) and scanning electron microscopy (SEM). The swelling experimental of the IPNs revealed that the hydrogels displayed definite pH sensitivity under physiological conditions, as well as sharp changes in the mesh size of their network as a function of the composition and pH of the swelling media. Bovine serum albumin (BSA) was chosen as a model protein to evaluate the permeation profile through the IPNs in both the simulated gastric and intestinal pH conditions. In all cases, it was found that the release rate of BSA was lower in acidic media (pH 2.6) and higher in basic media (pH 7.4).