腐植酸钠/聚N-异丙基丙烯酰胺/粘土杂化水凝胶的合成及脱色性能

以N-异丙基丙烯酰胺单体、粘土和腐植酸钠为原料合成了温敏腐植酸钠/聚N-异丙基丙烯酰胺/粘土（SH/PNIPA/clay）系列水凝胶。用红外光谱分析仪对其内部相互作用进行了研究,并用紫外可见分光光度计对水凝胶吸附-解吸亚甲基蓝的性能进行了测试。实验结果表明凝胶中SH与PNIPA形成了氢键;凝胶对亚甲基蓝（MB）的吸附和解吸能力受腐植酸钠的含量、粘土含量、亚甲基蓝的起始浓度和温度的影响。２％粘土含量和低温条件有利于凝胶吸附和解吸。     

腐植酸钠/聚N-异丙基丙烯酰胺/粘土杂化水凝胶的合成及脱色性能

腐植酸钠;聚N-异丙基丙烯酰胺;粘土;水凝胶;亚甲基蓝     

基于壳聚糖/聚丙烯酸/纳米银的高强抗菌水凝胶

首先以丙烯酸(AA)和壳聚糖(CS)为单体、N,N′-亚甲基双丙烯酰胺(MBA)为交联剂,通过光聚合法制备了CS/PAA双网络水凝胶,然后将Ag~+以硝酸银的形式分散在水凝胶中并通过紫外光辐照获得CS/PAA/纳米银复合水凝胶,并对复合水凝胶的抗菌性能进行研究。采用红外光谱对其结构进行表征,研究单体含量对水凝胶力学性能以及溶胀行为的影响。结果表明,当丙烯酸质量分数为20%,壳聚糖质量分数为5%的情况下,水凝胶的拉伸性能最优。此外,纳米银的引入有效提高了水凝胶的抗菌性能。     

聚N-异丙基丙烯酰胺/纳米SiO_2复合水凝胶的合成及溶胀性能

通过纳米SiO2的表面功能化,在其表面引入乙烯基功能基团,在H2OTHF的混合溶剂中,超声分散后,交联剂N,N′亚甲基双丙烯酰胺存在时,于25℃下使其与N异丙基丙烯酰胺共聚,制得聚N异丙基丙烯酰胺纳米SiO2复合水凝胶,并用FTIR和SEM对产物进行了表征.研究了凝胶的溶胀动力学,消溶胀动力学和温度敏感性.实验结果表明,纳米SiO2的引入,改善了聚N异丙基丙烯酰胺水凝胶在低温时的溶胀性能和在高温时对水的释放性能,并讨论了引起这些性能改变的原因.     

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.     

pH敏感水凝胶聚甲基丙烯酸的超声合成

在超声作用下,以甲基丙烯酸为原料,N,N’-亚甲基双丙烯酰胺为交联剂,过硫酸钾为引发剂,自由基引发聚合制备了pH敏感水凝胶聚甲基丙烯酸,采用红外光谱(FT-IR)和扫描电镜(SEM)对水凝胶分子结构与性能进行表征.在此基础上,重点研究了超声合成对于水凝胶的溶胀性能、消溶胀性能等性质的影响.实验结果表明,超声作用下合成的聚甲基丙烯酸水凝胶溶胀动力学性能以及响应灵敏性均优于常规合成方法.     

聚(N,N′-二乙基丙烯酰胺)水凝胶的制备及其溶胀动力学

以N,N′-二乙基丙烯酰胺(DEA)为单体,偶氮二异丁腈(AIBN)为引发剂,分别采用疏水性的1,2-二乙烯苯(DVB)和水溶性的N,N′-亚甲基双丙烯酰胺(BIS)为交联剂制备了温度敏感水凝胶聚(N,N′-二乙基丙烯酰胺)(PDEA).制得的PDEA水凝胶的低临界溶解温度(LCST)在30 ℃附近,初步讨论了交联剂的用量和性质对水凝胶性能的影响.并对其在不同温度下达到溶胀平衡时的溶胀比,去溶胀动力学及干凝胶的再溶胀动力学过程进行了研究.     

光化学合成P(DMAA-co-MMA)/Nano-SiO2复合水凝胶及其性能研究

以N,N-二甲基丙烯酰胺(DMAA)及甲基丙烯酸甲酯(MMA)为单体,Irgacure 2959为光引发剂,N,N′-二甲基双丙烯酰胺(Bis)为交联剂,利用紫外光引发自由基聚合制备了聚N,N′-二甲基丙烯酰胺(PDMAA)及P(DMAA-co-MMA)水凝胶,并通过加入少量表面改性后的纳米SiO₂对该水凝胶进行改性,制得了P(DMAA-co-MMA)/纳米SiO₂复合水凝胶,用FT-IR和SEM对产物进行了表征,同时研究该复合凝胶的溶胀动力学、消溶胀动力学、pH值响应性、离子强度等.该方法简便、快捷,大大缩短了聚合时间,合成过程仅需2-3 min.     

含甲基丙烯酸-N,N-二甲氨基乙酯水凝胶的紫外辐射合成及其性质研究

紫外光辐照 ,H2 O2 为光引发剂 ,N ,N′ 亚甲基双丙烯酰胺为交联剂合成了含甲基丙烯酸 N ,N 二甲氨基乙酯的水凝胶 .研究了水溶液中单体、光敏引发剂、交联剂浓度及光照时间对生成的水凝胶的凝胶含量和溶胀性能的影响 ,给出了最佳合成条件 .用该聚合法合成的聚甲基丙烯酸 N ,N 二甲氨基乙酯水凝胶不仅具有较好的透明性和适当的弹性 ,而且在 40℃和 pH =3时有明显的温度及 pH敏感性 .但离子强度对凝胶溶胀性能没有明显影响     

聚N-异丙基丙烯酰胺/纳米SiO2复合水凝胶的合成及溶胀性能

通过纳米SiO2的表面功能化,在其表面引入乙烯基功能基团,在H2O／THF的混合溶剂中,超声分散后,交联剂N,N′-亚甲基双丙烯酰胺存在时,于25℃下使其与N-异丙基丙烯酰胺共聚,制得聚N-异丙基丙烯酰胺,纳米SiO2复合水凝胶,并用FT-IR和SEM对产物进行了表征,研究了凝胶的溶胀动力学,消溶胀动力学和温度敏感性,实验结果表明,纳米SiO2的引入,改善了聚N-异丙基丙烯酰胺水凝胶在低温时的溶胀性能和在高温时对水的释放性能,并讨论了引起这些性能改变的原因。     

Studies of sodium humate/polyacrylamide/clay hybrid hydrogels. I. Swelling and rheological properties of hydrogels

A type of novel hybrid hydrogels from sodium humate (SH), polyacrylamide (PAM), and hydrophilic Laponite clay were prepared using potassium persulfate (KPS) as the initiator and N,N′-methylenebisacrylamide (MBA) as the cross-linker. The structures of the hydrogels were characterized by field emission scanning electron microscope and FTIR. Their swelling properties, swelling mechanism and rheological properties were also investigated. Experiments show that the composite is heterogeneous in the PAM/SH hydrogel system, while the clay collaborates with SH and improves the network structure of PAM/SH/clay hydrogel. High water-absorbing capability is shown for both hydrogel systems. Han plot proves that clay and SH are compatible with PAM for PAM/SH/clay hydrogels.     

A novel polyacrylamide nanocomposite hydrogel reinforced with natural chitosan nanofibers

Polyacrylamide (PAM) was used as a matrix material for fabricating novel nanocomposite hydrogels reinforced with natural chitosan nanofibers (CNFs) via in situ free-radical polymerization. The nanocomposite's structure, strength, morphology and rheological properties were investigated. The results showed that the CNFs had a strong interaction with PAM through hydrogen and covalent bondings. The CNFs acted as a multifunctional cross-linker and a reinforcing agent in the hydrogel system. The compression strength and storage modulus of the nanocomposite hydrogels were significantly higher than those of the pure PAM hydrogels and the corresponding PAM/chitosan semi-interpenetrating polymer network (PAM-SIPN) hydrogels. The swelling ratio (SR) of the nanocomposite hydrogels was lower than that of the PAM hydrogel, but was similar to that of the PAM-SIPN hydrogel. Among the CNF contents used, the 1.5 wt% CNF loading level showed the best combined swelling and mechanical properties for the hydrogels.     

Preparation and characterization of sodium carboxymethylcellulose/poly(N-isopropylacrylamide)/clay semi-IPN nanocomposite hydrogels

A new kind of pH-/temperature-responsive semi-interpenetrating polymer network hydrogels based on linear sodium carboxymethylcellulose (CMC) and poly(N-isopropylacrylamide) (PNIPA) cross-linked by inorganic clay (CMC/PNIPA/Clay hydrogel) was prepared. The temperature- and pH-responsive behaviors, the mechanical properties of these hydrogels were investigated. The CMC/PNIPA/Clay hydrogels exhibited a volume phase transition temperature around 32 °C with no significant deviation from the conventional PNIPA hydrogels. The swelling ratio of the CMC/PNIPA/Clay hydrogels gradually decreased with increasing the contents of clay. The influence of pH value on swelling behaviors showed that there is a maximum swelling ratio at pH 5.9. Moreover, the CMC/PNIPA/Clay hydrogels exhibited excellent mechanical properties with high tensile stress and elongation at break in excess of 1200%.     

交联聚(N-异丙基丙烯酰胺)/(海藻酸钠/聚(N-异丙基丙烯酰胺))半互穿网络水凝胶的制备及其溶胀性能

将线性聚(N-异丙基丙烯酰胺)(PNIPAAm)和海藻酸钠(SA)分子同时引入到PNIPAAm凝胶中,制备了交联聚(N-异丙基丙烯酰胺)/(海藻酸钠/聚(N-异丙基丙烯酰胺))半互穿网络(Cr-PNIPAAm/(SA/PNIPAAm)semi-IPN)水凝胶。在弱碱性条件下(pH=7.4),改变SA与线性PNIPAAm的质量比对Cr-PNIPAAm/(SA/PNIPAAm)semi-IPN水凝胶的溶胀度没有太大的影响。在酸性条件下(pH=1.0),其溶胀度随着SA与线性PNIPAAm质量比的减小而增大。由于亲水性SA与线性PNIPAAm的协同作用,Cr-PNIPAAm/(SA/PNIPAAm)semi-IPN水凝胶的消溶胀速率得到很大提高。     

Preparation and characterization of pH- and temperature-responsive semi-IPN hydrogels of carboxymethyl chitosan with poly (<Emphasis Type="Italic">N</Emphasis>-isopropyl acrylamide) crosslinked by clay

A new kind of pH- and temperature-responsive semi-interpenetrating polymer network hydrogel based on linear carboxymethylchitosan (CMCS) and poly (N-isopropylacrylamide) (PNIPA) crosslinked by inorganic clay was prepared. The pH-and temperature-responsive behaviors, the deswelling kinetics, and the mechanical properties of the hydrogel were investigated. The hydrogels exhibited a volume phase transition temperature around 33 °C with no significant deviation from the conventional PNIPA hydrogels. The results of the influence of pH value on the swelling behaviors showed that the minimum swelling ratios of the hydrogels appeared near the isoelectric point (IEP) of CMCS, and when pH deviated from the IEP, the hydrogels behaved as polycations or polyanions. The novel hydrogels had much higher response rate than the conventional CMCS/PNIPA hydrogels. Moreover, the semi-IPN hydrogels crosslinked by clay could be elongated to more than 800% and the elongation could be recovered almost completely and instantaneously.     

Swelling of N-isopropyl acrylamide hydrogels in aqueous solutions of sodium chloride

Hydrogels are three-dimensional networks of hydrophilic polymer chains. Hydrogels can absorb/desorb water and hydrophilic solutes. This behavior is called swelling/shrinking, as it is accompanied by a volume change. The amounts of absorbed substances depend on the structure of the hydrogel and the composition of the coexisting liquid phase. This paper deals with experimental investigations of the swelling behavior of nonionic, chemically crosslinked, synthetic hydrogels of N-isopropyl acrylamide. The swelling equilibrium of some hydrogels in aqueous solutions of sodium chloride was investigated at 298 K. The experimental results are presented, discussed and correlated/predicted with a thermodynamic model which combines an expression for the Gibbs energy of a liquid phase with an expression for the Helmholtz energy of an elastic network.     

Microwave-assisted synthesis of kC/Xylan/PVP-based blend hydrogel materials: physicochemical and rheological studies

Hydrogel systems composed of kC/Xylan (kC/OSX or kC/BX) blends and linear polyvinylpyrrolidone (PVP) were prepared in the presence of water soluble initiator sodium persulphate (KPS) with microwave irradiation. The hydrogel materials were investigated by measuring their syneresis, swelling, gel fraction, and rheological properties. Physicochemical and rheological properties of the natural polysaccharide (kC/Xylans) blends were modified significantly after blending with PVP. The introduction of PVP and the formation of semi-interpenetrating polymer network (semi-IPN) structure improved the gelling properties of the resulting hydrogels. It has been proven, that a high incorporation of PVP could only be obtained if the hydrogels were prepared using KPS initiator and microwave irradiation in combination. FTIR, CP-MAS ¹³C NMR, and elemental analysis confirmed the presence of PVP in the blends but no direct evidence for covalent bonds could be obtained.     

Graphene Oxide/Polyacrylamide/Aluminum Ion Cross‐Linked Carboxymethyl Hemicellulose Nanocomposite Hydrogels with Very Tough and Elastic Properties

Development of high‐strength hydrogels has recently attracted ever‐increasing attention. In this work, a new design strategy has been proposed to prepare graphene oxide (GO)/polyacrylamide (PAM)/aluminum ion (Al³⁺)‐cross‐linked carboxymethyl hemicellulose (Al‐CMH) nanocomposite hydrogels with very tough and elastic properties. GO/PAM/Al‐CMH hydrogels were synthesized by introducing graphene oxide (GO) into PAM/CMH hydrogel, followed by ionic cross‐linking of Al³⁺. The nanocomposite hydrogels were characterized by means of FTIR, X‐ray diffraction (XRD), and scanning electron microscopy/energy‐dispersive X‐ray analysis (SEM‐EDX) along with their swelling and mechanical properties. The maximum compressive strength and the Young's modulus of GO_3.5/PAM/Al‐CMH_0.45 hydrogel achieved values of up to 1.12 and 13.27 MPa, increased by approximately 6488 and 18330 % relative to the PAM hydrogel (0.017 and 0.072 MPa). The as‐prepared GO/PAM/Al‐CMH nanocomposite hydrogels possess high strength and great elasticity giving them potential in bioengineering and drug‐delivery system applications.     

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.