羧甲基壳聚糖/海藻酸钠半互穿网络水凝胶的制备及性能研究

以羧甲基壳聚糖(CMC)和海藻酸钠(SA)为原料,京尼平(GP)为交联剂,制备具有pH敏感性的CMC/SA半互穿网络(semi-IPN)水凝胶.利用特性黏数、红外光谱对CMC/SA水凝胶的半互穿网络结构及形成机理进行了分析与表征;对水凝胶的力学性能进行了测试;探讨了pH值及交联剂含量对水凝胶溶胀性能的影响.结果表明,京尼平交联的CMC/SA水凝胶具有半互穿网络结构.当w(CMC)∶w(SA)=5∶5时,CMC/SA水凝胶的断裂强度达到最大值(59 MPa),分别比纯的CMC(40 MPa)和SA(36 MPa)提高了47.5%和63.9%;当SA含量为60%时,CMC/SA水凝胶的断裂伸长率达到最大值(13.0%).当pH3.0时,溶胀率随pH值的增大而减小,pH=3.0时,溶胀率最小(186%);当pH3.0时,溶胀率随pH值的增大而增大,pH=9.0时,溶胀率最大(886%).京尼平交联的CMC/SA半互穿网络水凝胶具有明显的pH敏感性、溶胀可逆性及对pH的快速响应性.     

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.     

双重交联VSNPs-PAA纳米复合水凝胶的制备及其溶胀性能的研究

采用自由基聚合法合成了乙烯基硅纳米粒子-聚丙烯酸(VSNPs-PAA)双重交联复合水凝胶,考察了交联剂、引发剂、单体以及p H值、温度、盐溶液等对水凝胶溶胀行为的影响。结果表明,引发剂浓度为0.08%,交联剂浓度为0.1%,单体浓度为80%时,合成的水凝胶溶胀性能最大,吸水率达到5000%以上;该水凝胶不仅具有p H值敏感性和p H值变化下良好的反复性,而且在p H4的酸性溶液中表现出温度敏感性,其溶胀率随温度的升高而增大;水凝胶的溶胀率随着盐溶液浓度的增大而减小。     

壳聚糖水凝胶微球的制备与溶胀性能

采用三聚磷酸钠(TPP)和六偏磷酸钠(SHMP)为复合交联剂,制备了离子交联网络结构的壳聚糖水凝胶微球。分析讨论了交联剂质量配比、pH以及离子强度等对壳聚糖微球溶胀性能的影响。结果表明:使用复合交联剂制备的微球的溶胀度比单独使用TPP或SHMP的分别低62.4%和41.3%,交联效率得到明显提高;当m(TPP)∶m(SHMP)=3∶5,交联剂pH=5时,制备的微球交联程度最好,结构最密实;在pH=1.2的缓冲溶液中,溶胀度可达到357%,而且凝胶没有任何破碎。微球具有较好的离子强度和pH敏感性,在酸性介质中有较高的溶胀度。     

超大孔P(AA-co-AM)/PVA水凝胶的制备及吸附性能研究

采用泡沫分散聚合法,以饱和Na2CO3水溶液为发泡剂,过硫酸铵(APS)及NaHSO3为引发剂,N,N′-亚甲基双丙烯酰胺(MBA)为交联剂,聚(氧化乙烯/氧化丙烯)(PF127)为泡沫稳定剂,丙烯酸(AA)和丙烯酰胺(AM)为单体,聚乙烯醇(PVA)为第二网络,制备超大孔半互穿水凝胶P(AA-co-AM)/PVA,并研究其对阳离子兰染料的吸附性能。研究表明,P(AA-co-AM)/PVA具有相互贯穿的超大孔结构;当n(AM):n(AA)=1.5:1,w(PVA)=1.6%时凝胶的平衡溶胀度达186.56g/g;凝胶具有很好的离子响应性,在蒸馏水中的平衡溶胀度为129.16g/g时,在0.1mol/L NaCl溶液中只有31.07g/g;对阳离子兰染料溶液的脱色率达92.17%,吸附容量达17.16mg/g。     

pH敏感性P(AM-AA-co-C8PhEO10Ac)水凝胶溶胀动力学及其对茶碱的控释

以丙烯酰胺(AM)、丙烯酸(AA)和丙烯酸辛基酚聚氧乙烯醚酯(C8PhEO10Ac)为单体,采用自由基交联共聚法合成了具有pH敏感性的P(AM-AA-co-C8PhEO10Ac)水凝胶.研究了pH、单体配比对凝胶溶胀性能、溶胀动力学和退溶胀动力学的影响.初步探讨了模拟胃液(pH=1.4)、肠液(pH=7.4)中水凝胶对茶碱的控释情况.结果表明:凝胶具有高溶胀、退溶胀速率和良好的pH敏感性等特征;水凝胶的扩散行为在pH=7.4的缓冲溶液中为非Fickian扩散模式;载药凝胶在模拟肠液中对药物的累积释放率明显大于胃液中的累积释放率,其中n(C8PhEO10Ac)∶n(AM)∶n(AA)为1∶20∶30的载药水凝胶对茶碱的累积释放率最大.     

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     

聚乙烯醇/羧甲基壳聚糖共混水凝胶的辐射合成及性能

采用电子加速器辐照法制备了聚乙烯醇(PVA)/羧甲基壳聚糖(CMCH)共混水凝胶;研究了PVA与CMCH的配比、辐照剂量、温度以及pH值对PVA/CMCH共混水凝胶性能的影响.实验发现,PVA与CMCH在辐照剂量为40 kGy、配比为w(PVA)/w(CMCH)=5/1的条件下可得到强度较好的PVA/CMCH共混水凝胶,该水凝胶具有一定的温度和pH敏感性:在5~20℃时具有较高的溶胀率,温度在20℃以上溶胀率较低;水凝胶在pH<4.0和pH>6.0时溶胀率均较大,而当pH为4.0~6.0时溶胀率较小.     

PVA/P(AA-AM)水凝胶的制备及药物控制释放性能研究

以聚乙烯醇(PVA)、丙烯酸(AA)和丙烯酰胺(AM)为单体,过硫酸铵(APS)为引发剂、N,N'-亚甲基双丙烯酰胺(MBA)为交联剂,通过化学引发聚合制备互穿水凝胶PVA/P(AA-AM);用红外光谱(IR)、热重分析(TG)、差示扫描量热法(DSC)及扫描电镜(SEM)等测试方法对其进行了表征,并对其溶胀性能、p H敏感性以及离子强度对溶胀性能的影响进行了研究;并考察了该凝胶分别在p H=6.86和p H=1.80介质中对药物异烟肼和烟酸的控制释放行为。结果表明,PVA/P(AA-AM)水凝胶具有良好的p H、离子强度敏感性,在两种介质中异烟肼的累积释放率均高于烟酸,但异烟肼在p H=1.80的介质中的释放速度和累积释放率均高于其在p H=6.86的介质,烟酸则结果恰好相反。所以这种水凝胶有望用作靶向药物释放的载体。     

泡沫分散聚合法制备超大孔水凝胶及其性能研究

采用泡沫分散聚合法,以自制的4-乙酰基丙烯酰乙酸乙酯(AAEA)和2-丙烯酰胺基-2-甲基丙磺酸(AMPS)、丙烯酸(AA)为单体,制备了具有相互贯穿超大孔结构的快速响应型水凝胶.结果表明,引发剂和交联剂用量分别为2.5%和0.6%时平衡溶胀度最高;当以饱和碳酸钠溶液为发泡剂时制得的凝胶孔洞均匀贯穿;凝胶经无水乙醇处理...     

PVA/PAA thermo-crosslinking hydrogel fiber: preparation and pH-sensitive properties in electrolyte solution

The preparation of thermo-crosslinking hydrogel fibers composed of poly(vinyl alcohol) (PVA) and poly(acrylic acid) (PAA) was presented. The hydrogel fiber was prepared by extruding the spinning dope from in situ polymerization of acrylic acid in the presence of PVA into coagulating bath of saturated ammonium sulfate aqueous solution. The network was formed by thermally heating the dried fibers under vacuum. The final hydrogel fibers exhibit pH-sensitive behavior and show hysteresis loop in the pH range from 2.5 to 12.5. The pH value at which the swelling ratio of the fiber had a jump shifted to lower value with increasing the PAA content within the network. Increasing the heating temperature and time for the fibers, the swelling ratio decreased and the jump point pH shifted to higher pH value. The oscillatory swelling/contracting behavior of the hydrogel fiber exhibited a well reversible pH-responsive property.     

Fabrication and characterization of poly(vinyl alcohol)/chitosan hydrogel thin films via UV irradiation

A series of poly(vinyl alcohol)/chitosan (PVA/CTS) hydrogel thin films were prepared via ultraviolet (UV) irradiation, with acrylic acid (AA) monomer added as a crosslinker without the addition of any other photo-initiator. The swelling behaviors, intermolecular chemical bonds, molecular structures, thermal behaviors, degrees of crystallinity, morphologies of the surfaces and internal structure, and their relationship to the AA content were characterized using Fourier-transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), differential scanning calorimetry (DSC) and scanning electron microscopy (SEM). Poly(acrylic acid) (PAA) and its chemical crosslinks formed in hydrogel films via free-radical reactions were confirmed using FTIR and DSC analyses. The XRD patterns indicated that the degree of crystallinity of the hydrogel films decreased as the PAA content was increased. SEM micrographs showed that a uniform interconnected pore structure was formed through the entire hydrogel structure, and a gradient in the crosslinking density through the film thickness was observed to result from extended irradiation times. The swelling behaviors revealed that the formation of PAA and its crosslinking in the hydrogel thin films improved the pH stability and controlled the degree of swelling while retaining a high swelling rate. The successful formation of chemical crosslinking without any specific photo-initiator improves the natural characteristics of CTS and PVA and imparts the resulting PVA/CTS hydrogel thin films with properties that make them very promising in biomedical applications.     

PVA/PAA水凝胶纤维的电刺激响应性能

以过硫酸胺为引发剂,在PVA水溶液中原位聚合丙烯酸单体,得到的PVA／PAA混合水溶液在凝固浴硫酸胺饱和水溶液中纺丝制备了物理缠结和氢固定网络形式的PVA／PAA水凝胶纤维。该纤维于NaCl溶液中在直流电场作用下具有电流－刺激敏感性,表现为溶胀、收缩、弯曲行为。纤维的弯曲速度和最大弯曲度随电场强度和凝胶网络中PAA含量的增加而增大,随电解质溶液离子强度的变化出现临界最大值。纤维向负极弯曲的过程中,在电场下自由离子和反庆子迁移引起的渗透压主导作用,弯曲过程主要是溶胀弯曲;向正极弯曲过程中,由于电化学反应和电场作用下产生的PH梯度导致凝胶网络构像变化主导作用,弯曲主要是收缩弯曲;弯曲由负极向正极转化过程中,两种机理对弯曲的影响相对平衡。     

Synthesis,characterization, and swelling behaviors of chitosan‐g‐poly(acrylic acid)/poly(vinyl alcohol) semi‐IPN superabsorbent hydrogels

A series of granulated semi‐interpenetrating polymer network (semi‐IPN) superabsorbent hydrogels composed of chitosan‐g‐poly(acrylic acid) (CTS‐g‐PAA) and poly(vinyl alcohol) (PVA) were prepared by solution polymerization using ammonium persulfate (APS) as an initiator and N,N′‐methylenebisacrylamide (MBA) as a crosslinker. The effects of reaction conditions such as the concentration of MBA, the weight ratio of AA to CTS, and the content of PVA on water absorbency were investigated. Infrared (IR) spectra and differential scanning calorimetry (DSC) analyses confirmed that AA had been grafted onto CTS backbone, and PVA semi‐interpenetrating into CTS‐g‐PAA networks. SEM analyses indicated that CTS‐g‐PAA/PVA has improved porous surface and PVA was uniformly dispersed in CTS‐g‐PAA network. The semi‐IPN hydrogel containing 10 wt% PVA shows the highest water absorbency of 353 and 53 g g^?1 in distilled water and 0.9 wt% NaCl solution, respectively. Swelling behaviors revealed that the introduction of PVA could improve the swelling rate and enhance the pH stability of the superabsorbent hydrogel. Copyright © 2009 John Wiley & Sons, Ltd.     

Manufacturing of pH sensitive PVA/PVP/MWCNT and PVA/PEG/MWCNT nanocomposites: an approach for significant drug release

The purpose of this paper is studying the effect of incorporation of Multiwall Carbon Nanotubes (MWCNT) into two different nanocomposites in poly vinyl alcohol (PVA)/polyvinylpyrrolidone (PVP), and PVA/Polyethylene glycol (PEG). MWCNT were synthesized by chemical vapor deposition (CVD) method using acetylene and Fe/Co/Al₂O₃ as carbon precursor and catalyst, respectively. Nitric acid and sulfuric acid were used for purification and functionalization of MWCNT. Afterward, highly pure and functionalized MWCNT (0, 0.02, and 0.05% w/w) were incorporated in PVA/PVP and PVA/PEG to synthesize PVA/PVP/MWCNT and PVA/PEG/MWCNT nanocomposites hydrogel membranes that cross-linked by freezing–thawing. PEG and PVP were selected in these nanocomposites as dispersion matrix for MWCNT as well as for increasing the elasticity of the nanocomposites membranes. The morphology of the hydrogels was characterized by SEM, FTIR, XRD, TGA, and the mechanical properties of the hydrogel membranes were investigated. The swelling behavior in different pH-buffer solutions was studied as well as studying weight loss percentage and swelling kinetic. The drug releasing process of the hydrogel membranes was investigated using salicylic acid as a model drug. It was found that MWCNT are dispersed well into the polymers and crystallinity, mechanical properties and thermal stability of the hydrogels contain MWCNT are better than that without MWCNT. Maximum degree of swelling was observed at pH 7 and swelling degree increases with increasing the ratio of MWCNT in the hydrogels from 0.02 to 0.05%. All hydrogel membranes followed non-Fickian mechanism and drug releasing were controlled by varying the pH and amount of MWCNT.     

羧甲基壳聚糖水凝胶制备及其在药物控释中的应用

以戊二醛为交联剂制备了一系列羧甲基壳聚糖pH敏感水凝胶 .研究了合成条件对羧甲基壳聚糖水凝胶溶胀性能的影响 .实验结果表明羧甲基壳聚糖的脱乙酰度、交联剂用量对水凝胶溶胀率的影响较大 .pH=3 0时 ,水凝胶收缩 ,而pH =1 0 ,5 0 ,7 4 ,9 0时 ,水凝胶溶胀 ,且在碱性条件下水凝胶的溶胀率远大于酸性条件下的溶胀率 .包埋在此水凝胶中的水杨酸释放随载药介质的pH值和水凝胶半径大小的变化而显著不同 ,pH =1 0条件下载药的水凝胶的释药率大于pH =7 4 ,12 0条件下的释药率 ,且水凝胶的半径越大 ,释药速度和释药率也越大     

Synthesis and characterization of a novel controlled release nitrogen-phosphorus fertilizer hybrid nanocomposite based on banana peel cellulose and layered double hydroxides nanosheets

In the present study, a novel environment-friendly hybrid nanocomposite of Banana Peel Cellulose-g-poly(acrylic acid)/PVA (BPC-g-PAA/PVA) hydrogel and Layered double hydroxides (LDH) nanosheets was developed using in situ graft polymerization for slow release of NP (nitrogen, phosphorous) fertilizers and water retention. The hybrid nanocomposite hydrogel containing NP fertilizers was characterized using FTIR, and SEM. The effects of pH changes and different saline solutions on the swelling behavior, fertilizer release and water retention properties of the nanocomposite were investigated.The nanocomposite hydrogel showed a pH dependent swelling, as in the pH range of 7–10, the hydrogel had higher water absorbency. However, pH had opposite effects on the release of fertilizers. Phosphorus release had an increasing trend from pH 2 to 7 and it reached its maximum value at normal pH while nitrogen had a higher release rate at acidic pH and by increasing pH from 2 to 7, the release of nitrogen decreased gradually. Water absorption and fertilizer release of hydrogel was influenced by different cations in the order of Ca²⁺ < K⁺ < Na⁺. Water retention study in loamy sand soil showed that the nanocomposite hydrogel significantly improved the water retention of the soil for a longer period of time, compared to neat BPC-gPAA. This result indicated that incorporation of LDH nanosheets in hydrogel matrix improved its water retention property. The obtained results revealed that the nanocomposite of BPC-g-PAA/PVA hydrogel and LDH nanosheets can be a promising controlled release fertilizer formulation with enhanced water retention properties for agricultural applications.     

Synthesis of Carboxymethyl Cellulose Based Drug Carrier Hydrogel Using Ionizing Radiation for Possible Use as Site Specific Delivery System

A unique natural polymer based colon specific drug carrier was prepared from carboxymethyl cellulose (CMC) and acrylic acid (AAc) in aqueous solution employing γ‐radiation induced copolymerization and crosslinking. The effect of preparation conditions such as the natural polymer content and irradiation dose on gelation process was investigated. The swelling behavior of the prepared hydrogels was characterized by investigating the time and pH dependent swelling of the (CMC/AAc) hydrogels of different CMC content. The effects of the hydrogel composition and pH of the swelling medium on the swelling indices were estimated. The results show that the increment in the CMC content in the feed solution enhances the gelation process. The results also show the dependence of the swelling indices on both hydrogel composition and pH value of the swelling medium. To evaluate the ability of the prepared hydrogel to be used as a colon‐specific drug carrier, the release profile of theophylline was studied as a function of time at pH 1 and pH 7.