壳聚糖/明胶/聚乙烯醇复合水凝胶的溶胀性能研究

以聚乙烯醇(PVA)、明胶和壳聚糖为原料,以戊二醛为交联剂,在醋酸溶液中通过共混交联反应合成了壳聚糖/明胶/聚乙烯醇复合水凝胶,考察了聚乙烯醇/壳聚糖/明胶的质量比、交联剂用量、反应温度、反应时间对复合水凝胶溶胀性能的影响。通过正交实验,确定制备复合水凝胶的优化条件如下:交联剂用量为6 mL、反应温度为75℃、反应时间为70 min、聚乙烯醇/壳聚糖/明胶的质量比为1∶2∶2,在此优化条件下合成的壳聚糖/明胶/聚乙烯醇复合水凝胶溶胀性能良好,对水的平衡溶胀度达到985%。     

Cs-AA-HEMA复合水凝胶的合成及溶胀性能

以壳聚糖、丙烯酸、甲基丙烯酸羟乙酯为原料,硝酸铈铵、过氧化二苯甲酰为引发剂,戊二醛为交联剂,制备了壳聚糖-丙烯酸-甲基丙烯酸羟乙酯复合水凝胶,探讨了凝胶溶胀过程和理论,研究了凝胶合成条件及溶剂性质对凝胶平衡溶胀度的影响.结果表明：随着丙烯酸浓度、甲基丙烯酸羟乙酯添加量的增加,凝胶平衡溶胀度先增大再减小,凝胶溶胀度随着戊二醛浓度增加而减小.壳聚糖-丙烯酸-甲基丙烯酸羟乙酯复合水凝胶是pH/离子/温度敏感型凝胶.     

壳聚糖/聚乙烯醇复合水凝胶制备及性能研究

成功制备了壳聚糖/聚乙烯醇(CS/PVA)复合水凝胶。考察了聚乙烯醇与壳聚糖的质量比及戊二醛用量等对水凝胶溶胀度、机械强度等的影响。结果表明:当聚乙烯醇与壳聚糖质量比为2,戊二醛浓度为0.213 mol/L时,水凝胶的综合性能最佳。     

壳聚糖纤维/壳聚糖/海藻酸钠水凝胶溶胀性能与抑菌性能

制备了壳聚糖(CS)/海藻酸钠(SA)复合水凝胶,并通过加入吸水性壳聚糖长纤维、45%壳聚糖水刺无纺布、80%壳聚糖水刺无纺布、100%壳聚糖水刺无纺布、100%壳聚糖针刺无纺布这五种纤维,增强复合水凝胶的力学性能,探究了复合水凝胶的吸水溶胀性能与抑菌性能。结果表明,加入纤维后水凝胶在蒸馏水中的溶胀比明显降低,在碱性环境中,水凝胶的溶胀比显著上升,在偏中性环境中,水凝胶的溶胀比最低;加入纤维后,复合水凝胶仍具有一定的抑菌性,无纤维添加的水凝胶呈现出的抑菌能力一般,而加入了吸水性壳聚糖长纤维的具有最佳的抑菌性能。     

聚乙烯醇-壳聚糖互穿网络水凝胶的合成与性能研究

以聚乙烯醇和壳聚糖为原料合成了聚乙烯醇-壳聚糖互穿网络水凝胶,研究了聚乙烯醇与壳聚糖质量比、溶剂醋酸溶液体积、交联剂戊二醛浓度等对聚乙烯醇-壳聚糖互穿网络水凝胶溶胀性能和硬度的影响,得到了最佳合成条件.随着聚乙烯醇与壳聚糖质量比、交联剂戊二醛浓度的增大及溶剂醋酸溶液体积减小,凝胶溶胀度减小而硬度增大.聚乙烯醇-壳聚糖凝胶具有良好的生物相容性.     

温度及pH敏感性聚乙烯醇/羧甲基壳聚糖水凝胶的制备与性能研究

以聚乙烯醇(PVA)和羧甲基壳聚糖(CMCh)为原料,采用60Co-γ射线辐照交联制备聚乙烯醇/羧甲基壳聚糖(PVA/CMCh)水凝胶;研究了PVA与CMCh的配比、温度、pH及离子强度等对PVA/CMCh水凝胶溶胀率的影响。结果表明适当配比的PVA/CMCh水凝胶具有一定的温度、pH及离子敏感性。该水凝胶在5~20°C时具有较高的溶胀率,温度在20°C以上溶胀率较低,并且有一定的可逆性;水凝胶在pH较低(pH<4.0)和较高(pH>6.0)时溶胀率均较大,而当pH为4.0~6.0时溶胀率较小,显示出一定的pH敏感性。     

壳聚糖-透明质酸复合凝胶的制备

合成了壳聚糖-透明质酸复合凝胶（壳聚糖15g/L,透明质酸1g/L,交联剂戊二醛用量为壳聚糖-透明质酸质量的30%,即4.8g/L,室温下放置24h）,以改善单纯壳聚糖凝胶脆性较大、黏弹性及持水能力较弱等性能。壳聚糖与透明质酸在复合水凝胶中未发生微相分离,具有良好的相容性。与单纯的壳聚糖凝胶相比,含有透明质酸的复合凝胶具有较好的弹性及持水性能等。复合凝胶水分保持能力随凝胶中透明质酸含量的增大而增大,高温条件下复合凝胶持水能力更显著优于单纯壳聚糖凝胶。复合凝胶随温度、pH值等外界条件的改变会出现规律性的溶胀或收缩,具有作为智能材料使用的前景。     

聚乙烯醇/聚丙烯酸钠/Zn0.2Fe2.8O4复合水凝胶的制备及其溶胀行为

将水溶性纳米Zn0.2Fe2.8O4(ZFO)粒子、用氢氧化钠(NaOH)中和的丙烯酸(PAAS)加入一定量的聚乙烯醇(PVA)水溶液中分散均匀,再加入引发剂过硫酸钾、交联剂N,N’-亚甲基双丙烯酰胺引发聚合,制备了PVA/PAAS/ZFO水凝胶。采用傅里叶红外光谱仪(FTIR)、透射电子显微镜(TEM)对其组成和结构进行表征,并系统研究了复合水凝胶在不同溶剂中的溶胀性能。结果表明,纳米ZFO粒子均匀分散在PVA/PAAS凝胶网络中,纳米ZFO粒子的加入使水凝胶的溶胀速率和平衡溶胀度先增加后减小,在纳米ZFO含量为1%时达到最大;在不同浓度的电解质溶液和不同pH值的溶液中进行溶胀时,水凝胶表现出良好的离子浓度和p H刺激响应性。     

PVA/SA复合水凝胶溶胀及无机三氮离子传递性能

以聚乙烯醇（PVA）、海藻酸钠（SA）、活性炭、硼酸和氯化钙为原料,制备复合水凝胶微生物固定化载体材料,分析了离子在水凝胶膜中的扩散渗透机理,采用池膜法测定水凝胶的NH⁺₄、NO^-₂、NO^-₃离子扩散性能。结果表明,在PVA、SA、活性炭含量分别为4％、2.0%及0.2%时,以5%的氯化钙的饱和硼酸溶液为交联剂,交联时间15 min的条件下制备的固定化脱氮微生物载体传递性能最佳。复合水凝胶平衡溶胀度、扩散系数随PVA浓度升高而增大,随SA浓度升高溶胀度降低,离子扩散系数起初随SA浓度升高而升高,随后出现拐点。3种无机氮离子在水凝胶中的传递速率依次为NH⁺₄>NO^-₂>NO^-₃,遵从离子有效截面积小,传递速率大的规律。改变水凝胶制备条件、原料配比对NO^-₂、NH⁺₄的渗透系数影响较大,而对NO^-₃影响较小。     

可注射甘油磷酸钠-壳聚糖/海藻酸钠复合水凝胶的制备及性能研究

通过物理交联方法,将海藻酸钠(SA)与甘油磷酸钠-壳聚糖(GP-CS)复合制备可注射GP-CS/SA复合水凝胶,考察了物料比(GP-CS与SA的质量比)对复合水凝胶凝胶化时间、溶胶含量、微观形态、热稳定性、平衡溶胀等物理化学性能的影响。结果表明,复合水凝胶中SA比例越大,凝胶化时间越短,溶胶含量越少;扫描电镜和红外光谱分析表明,GP-CS与SA通过物理交联形成三维网络结构的水凝胶;热重分析表明,复合水凝胶与GP-CS水凝胶的热稳定性没有很显著差异;平衡溶胀实验表明,随着SA比例的增大,复合水凝胶的溶胀率和平衡溶胀率升高。GP-CS/SA复合水凝胶比单一的GP-CS水凝胶具有更高的机械强度、更好的吸水性和平衡溶胀性能。     

The release of cefazolin from chitosan/polyvinyl alcohol/sepiolite nanocomposite hydrogel films

Films of chitosan/polyvinyl alcohol (PVA)/sepiolite nanocomposite were prepared by a simple and “green” route through solution mixing; followed by freezing–thawing cycles. The structures of nanocomposites were characterized by transmission electron microscopy (TEM), scanning electron microscopy (SEM), thermogravimetric analysis, X-ray diffractometry, and Fourier transform infrared spectroscopy. The SEM and TEM micrographs confirmed a needle-type dispersion of sepiolite nanoclay in the hydrogel nanocomposites. The effects of sepiolite and chitosan/PVA weight ratio on the swelling of nanocomposites were investigated. The water absorbency of nanocomposites was decreased by introducing sepiolite nanoclay. The nanocomposites with high content of chitosan showed high swelling capacity. The nanocomposite films showed pH-dependent swelling behavior with a maximum water absorbency under acidic pH. The cefazolin with a broad-spectrum activity toward gram-positive and gram-negative bacteria was loaded in hydrogels. The release of cefazolin from nanocomposites was evaluated at pH 7.4. The content of released drug was affected by both sepiolite amount and chitosan/PVA weight ratio. The nanocomposites films released more cefazolin than the neat hydrogel film. Cefazolin-loaded nanocomposites showed the antibacterial activity with a large zone of inhibition against gram-positive Bacillus cereus bacterium.     

Radiation synthesis of graphene oxide/composite hydrogels and their ability for potential dye adsorption from wastewater

A high yield of graphene oxide (GO) was chemically synthesized from graphite powder utilizing adjusted Hummer's method. The contents of acidic functional groups in GO were determined using potentiometric titration. Composite hydrogels dependent on graphene oxide/poly(2-acrylamido-2-methylpropanesulfonic acid)/polyvinyl alcohol (GO/PAMPS/PVA) were synthesized utilizing a ⁶⁰Co gamma irradiation source at different doses. The synthesized graphene oxide and composite hydrogels were portrayed via X-ray diffraction, thermogravimetric analysis, and Fourier transform infrared analysis. The morphology of composite hydrogels was characterized by scanning electron microscope. The gel % and swelling % for the prepared hydrogel demonstrated that the swelling % of hydrogel increased with raising AMPS content. Whereas the increment of GO and increasing the irradiation dose lead to a reduction in the swelling %. The influences of pH, GO percentage, initial dye concentration, the adsorbent dosage, contact time, and temperature on the adsorption of basic blue 3 dye were evaluated and the adsorption capacity was 194.6 mg/g at optimum conditions; pH = 6, GO/PAMPS/PVA composite hydrogels with 5 wt% of GO, initial dye concentration = 200 mg/L, adsorbent dose = 0.1 g, solution volume = 50 mL after 360 min at room temperature (25°C). The adsorption of dye onto the GO/PAMPS/PVA composite hydrogels follows Pseudo-second-order adsorption kinetics, fits the Freundlich adsorption isotherm model.     

Preparation and swelling properties of a starch-g-poly(acrylic acid)/organo-mordenite hydrogel composite

A novel hydrogel composite was prepared via inverse suspension polymerization using starch, acrylic acid and organo-mordenite micropowder with the crosslinker, N,N′-methylenebisacrylamide and the initiator, potassium persulfate. Fourier transform infrared spectroscopy, X-ray diffraction spectroscopy, scanning electron microscopy, and energy dispersive spectroscopy confirmed that the acrylic acid was grafted onto the backbone of the corn starch, that the organo-mordenite participated in the polymerization, and that the addition of organo-mordenite improved the surface morphology of the hydrogel composite. The swelling capacity of the hydrogel composite was evaluated in distilled water, and solutions with different pH values, and various salt solutions. It was found that the incorporation of 10 wt-% organo-mordenite enhanced the water absorbency by 144% (from 268 to 655 g·g⁻¹) and swelling was extremely sensitive to the pH values, the concentration of the salt solution and cation type. Swelling kinetics and water diffusion mechanism of the hydrogel composite in distilled water were also discussed. Moreover, the hydrogel composite showed excellent reversibility of water absorption even after five repetitive cycles and the hydrogel composite exhibited significant environmental-responsiveness by changing the swelling medium from distilled water to 0.1 mol·L⁻¹ NaCl solution. In addition, the loading and release of urea by the hydrogel composite were tested and the nutrient-slow-release capability of this material was found to be suitable for many potential applications.     

Ethylcellulose microparticles containing chitosan and gelatin: pH-dependent release caused by complex coacervation

Ethylcellulose microparticles containing chitosan and gelatin were prepared by spray drying water-in-oil (W/O) emulsion. Water phase was chitosan:gelatin solution in distilled water, and oil phase was ethylcellulose solution in dichloromethane. FITC-dextran was included in water phase as a fluorescence dye. The maximum coacervation was observed at pH 6.0 when the ratio of chitosan to gelatin was 1:15. Microparticles containing chitosan and gelatin in the ratio showed a higher release under acidic condition (e.g. pH 4.0) and neutral condition (e.g. pH 7.0), but a lower release at pH 5.0 and pH 6.0. The complex coacervate composed of chitosan and gelatin was efficiently formed at those pHs, and the formation of coacervate would be responsible for the lower release.     

Enhancing the crystallization and orientation of electrospinning poly (lactic acid) (PLLA) by combining with additives

Novel hydrogel films composed of hydroxyethylacryl chitosan (HC) and sodium alginate (SA) were prepared for biomedical application by using calcium chloride (CaCl₂) as a nontoxic ionic crosslinker to form a semi-interpenetrating polymer network (semi-IPN). HC was successfully prepared by following a Michael addition reaction of chitosan (CS) and hydroxyethylacrylate completely dissolved in distilled water at 70 °C. The distribution pattern of Ca²⁺ ions were well-dispersed within the hydrogel films examined by scanning electron microscope-energy dispersive spectrometry (SEM-EDS), implying uniformity of crosslinking. The swelling behavior of the hydrogel films in distilled water, simulated gastric fluid (SGF, pH?=?1.2) and phosphate buffer solution (PBS, pH?=?7.4) were investigated. The equilibrium swelling degree of the hydrogel films in distilled water increased with a decreas of either the SA content or the concentration of CaCl₂. The hydrogel films showed pH-dependent behavior in that the shapes of the hydrogel films were stable in SGF while they degraded in PBS. The tensile strength and elongation of the hydrogel films reached 12.1 MPa and 162%, respectively, which presented reasonable mechanical properties during use and enough flexibility to follow skin movement. Cell viability of the hydrogels was measured using a methylthiazol tetrazolium (MTT) assay. The results indicated that the hydrogel films are not cytotoxic.     

壳聚糖/聚乙烯醇液态地膜的制备与应用

采用溶液共混法将壳聚糖和聚乙烯醇制备成可降解液态地膜,研究了壳聚糖溶液与聚乙烯醇溶液的质量比对共混干膜的力学性能、水蒸气透过率和水溶性的影响规律,还测定了液态地膜对土壤含水率、蔬菜种子发芽率及大棚番茄生长发育的影响.结果表明,当壳聚糖溶液(浓度为1.0％,质量分数,下同)和聚乙烯醇溶液(浓度为4.0％)的质量比(mA:...     

壳聚糖/聚醚半互穿网络水凝胶的性能

以壳聚糖和聚醚为原料,戊二醛为交联剂,在醋酸溶液中制备了壳聚糖/聚醚水凝胶,反应温度45℃,聚醚和壳聚糖的质量比为0.4,戊二醛浓度为0.053 mol/L,壳聚糖黏均相对分子质量为24.86×104时,其凝胶饱和溶胀度为876.25%;反应温度45℃,聚醚和壳聚糖的质量比为0.6,戊二醛浓度为0.267 mol/L,壳聚糖黏均相对分子质量为24.86×104时,其凝胶硬度为151.896 kPa。     

Temperature and pH‐response swelling behavior of poly(2‐ethyl‐2‐oxazoline)/chitosan interpenetrating polymer network hydrogels

Interpenetrating polymer network (IPN) hydrogels composed of poly(2‐ethyl‐2‐oxazoline) (PEtOz) and chitosan (CS) were prepared with radical polymerization and were characterized for their swelling properties. Sample OC11 (hydrogel weight ratio PEtOz/CS = 1/1) swelled more than samples OC21 (PEtOz/CS = 2/1) and OC31 (PEtOz/CS =3/1), exhibiting a swelling ratio of about 2000 wt % in deionized water; the swelling ratios of the other samples were about 1000 and 700 wt %. The swelling behavior of the IPN hydrogels was observed under various pH and temperature conditions. The swelling ratios of the samples ranged from about 2000 to 6500 wt % at lower pHs, with a maximum swelling ratio of about 6500 wt % in a pH 2 aqueous solution. They exhibited low critical solution temperature behavior, with sample OC31 more sensitive to temperature and sample OC11 more sensitive to pH. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 99: 1100–1103, 2006