新型黄原胶基高吸水性树脂的合成

在水溶性引发剂过硫酸钾的引发下,使丙烯酸（AA）在黄原胶（XG）分子链上接枝聚合,并加入N,N′-亚甲基双丙烯酰胺进行一定程度的交联,制备高吸水性树脂。研究了反应条件对产品吸水率的影响,利用傅里叶红外光谱、X射线衍射、偏光显微镜对接枝共聚物进行表征。实验结果表明：最佳合成条件AA与XG质量比m(AA) ∶m(XG)=6∶1,交联剂、引发剂与黄原胶的质量比分别为0.01和0.003,丙烯酸的中和度为70%,反应温度为60 ℃,反应时间为4 h。最佳合成条件下制备的树脂最大吸水倍数854 g/g,吸生理盐水倍数156 g/g。     

Preparation and characterization of a novel pH‐, thermo‐, and ionic strength‐responsive hydrogels based on xanthan gum–poly(aspartic acid)

A series of interpenetrating polymer networks (IPN) hydrogels with different compositions that based on xanthan gum (XG) and poly(aspartic acid) (PASP) were synthesized. The effects of various external surrounding stimuli, including pH, temperature, and ionic strength on XG–PASP hydrogels swelling properties were investigated. Chemical structural changes of the IPN hydrogels were characterized by Fourier transform infrared spectroscopy (FT‐IR), differential scanning calorimetry (DSC), transmission electron microscopy (TEM), and swelling ratio measurement. The swelling process was found to be a Fickian diffusion and reached swelling equilibrium quickly. It was found that the feed composition of PASP was an important factor that affected the properties of IPN hydrogels. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007     

Konjac glucomannan and xanthan gum as compression coat for colonic drug delivery:experimental and theoretical evaluations

Compression coated tablets for oral colon specific delivery systems were developed with a mixture polysaccharide of konjac glucomannan (KGM) and xanthan gum (XG) as the compression coat. Diffusion of cimetidine from compression coated tablets was investigated by release experiment in Vitro. 0.22U/mL β-mannanase was applied in the mimic colon solution. The structure of the mixture polysaccharide was studied by an atomic force microscope (AFM). The experimental results indicate that a KGM70 tablet with a 0.4 g coat is of good design, due to a less than 5% drug loss in the mimic upper gastrointestinal solution by the synergistic interaction between XG and KGM, and due to about 50% cumulative release in the mimic colon solution by degradation after 24 hours. The release mechanism and model are discussed based on different periods of drug release including the delay of the drug, the constant release without an enzyme and the delay of degradation. Under hydrolysis by β-mannanase, drug release from the tablet with KGM coat shows an exponential increase, while that from the dosage with the mixture polysaccharide coat is an approximately zero-order process in which the constant release rate relates to the release velocity of a non-degraded system, the content of KGM within the coat and the average molecular weight ratio of KGM to XG. It was found that XG was the framework of the polysaccharide mixtures by AFM, which is similar to the analysis results from experiments on drug release.     

Konjac glucomannan and xanthan gum as compression coat for colonic drug delivery: experimental and theoretical evaluations

Compression coated tablets for oral colon specific delivery systems were developed with a mixture polysaccharide of konjac glucomannan (KGM) and xanthan gum (XG) as the compression coat. Diffusion of cimetidine from compression coated tablets was investigated by release experiment in Vitro. 0.22U/mL β-mannanase was applied in the mimic colon solution. The structure of the mixture polysaccharide was studied by an atomic force microscope (AFM). The experimental results indicate that a KGM70 tablet with a 0.4 g coat is of good design, due to a less than 5% drug loss in the mimic upper gastrointestinal solution by the synergistic interaction between XG and KGM, and due to about 50% cumulative release in the mimic colon solution by degradation after 24 hours. The release mechanism and model are discussed based on different periods of drug release including the delay of the drug, the constant release without an enzyme and the delay of degradation. Under hydrolysis by β-mannanase, drug release from the tablet with KGM coat shows an exponential increase, while that from the dosage with the mixture polysaccharide coat is an approximately zero-order process in which the constant release rate relates to the release velocity of a non-degraded system, the content of KGM within the coat and the average molecular weight ratio of KGM to XG. It was found that XG was the framework of the polysaccharide mixtures by AFM, which is similar to the analysis results from experiments on drug release.     

Hybrid PVA-xanthan gum hydrogels as nucleus pulposus substitutes

Hybrid hydrogels were synthesized mixing poly(vinyl alcohol) (PVA) and xanthan gum (XG) in different molar ratios and using trisodium trimetaphosphate, as crosslinking agent, to obtain potential nucleus pulposus substitutes. Human Nucleus Pulposus (NP) is a hydrogel-like tissue with peculiar properties, which determine its role in supporting and dissipating spinal loads. Hydrogel obtained mixing PVA and XG in molar ratio 4:1 (PX25) showed mechanical, swelling, and thermal properties, i.e., heat capacity, which make it a good candidate as a potential NP substitute. Preliminary cytotoxicity tests pointed out that the developed materials did not show any signs of cytotoxicity towards NIH3T3 cells.     

海泡石/黄原胶复合絮凝剂的制备及应用研究

以过硫酸钾为引发剂,使丙烯酸/丙烯酰胺在黄原胶(XG)分子链上接枝聚合并复合海泡石纤维制备复合絮凝剂。研究了反应条件对含油废水COD去除率及浊度去除率的影响,利用红外光谱(FTIR)对接枝产物进行表征。实验结果表明,最佳合成条件为:m(丙烯酸/丙烯酰胺)∶m(黄原胶)=8∶1,引发剂、交联剂与黄原胶质量比分别为0.02,0.006,m(海泡石)∶m(黄原胶)=1∶2,反应温度60℃,用该絮凝剂处理含油废水,COD去除率和浊度去除率分别达到88.2%和95.6%。     

Electroresponsive and spinnable hydrogels from xanthan gum and gelatin enhanced by Fe3+ ions coordination

Polyelectrolyte hydrogels with spinnability and electroresponsive were prepared from xanthan gum (XG) and gelatin. Oscillatory rheological measurements were utilized to explore mechanical properties and thermal stability of the resultant XG-Gelatin5 hydrogels. The XG-Gelatin5 hydrogels possessed higher strength and larger critical strain than these of the XG hydrogels, demonstrating existence of synergistic interactions. The XG-Gelatin5 hydrogels were stable in temperature range of 20–60°C, and gradually release drug with controlled manner in neutral and acid medium at 37°C. The self-recoverable and thixotropic XG-Gelatin5 hydrogels were extruded to form hydrogel fibers, and the dried hydrogel fibers rapidly bend towards cathode under applied voltage. Long hydrogel fibers were harvested with enhancement by Fe³⁺ ions, and were weaved and braided to obtain hydrogel fiber constructs. The XG-Gelatin5 hydrogel fibers with electroresponsive and controlled drug release possess potential applications in biomaterials, tissue engineering, and drug carrier fields.     

Preparation of microspheres with microballoons inside for floating drug‐delivery systems

The use of floating drug‐delivery systems is one method that is used to achieve prolonged gastric residence times. We developed a novel, multiple‐unit, floating drug‐delivery system of microspheres with microballoons inside from xanthan gum (XG) and gelatin (GA) by a water‐in‐oil method. With theophylline as the model drug, four formulations (FI–FIV) with different ratios of the two polymers were prepared. The size distribution, drug‐encapsulation efficiency, floating behavior, release characteristics, and morphological properties were investigated. The ratio of the two polymers influenced the size distribution, encapsulation efficiency, and drug release appreciably. With increasing amounts of GA, the percentage yield of the floating microspheres and the drug‐encapsulation efficiency decreased from 100 and 84.5% to 31 and 56.2%, respectively. The drug‐release rate also decreased with increasing GA content, which was attributed to an increase in the crosslinking extent. An initial burst was observed, and after that, the drug was released slowly by a near‐zero‐order pattern, which was attributed to the low solubility of theophylline and the possible complexes formed by XG and GA in the simulated gastric fluid (pH 1.2). © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 94: 197–202, 2004     

魔芋葡甘聚糖复合凝胶的制备及其溶胀性能研究

通过在水中复配魔芋葡甘聚糖(KGM)、黄原胶(XG)和β-环糊精(β-CD),制备了KGM/XG/β-CD复合水凝胶。探讨了β-CD含量对凝胶平衡溶胀度的影响,并探讨了介质pH和温度对凝胶溶胀度的影响。结果表明,当m(KGM):m(XG):m(β-CD)=1:1:1时,复合凝胶的平衡溶胀度最大;复合凝胶的溶胀度在溶胀初期增加很快,随着溶胀时间的延长,溶胀度增加变慢,约7 h内基本达到平衡;随着介质pH的增大或体系温度从25℃增加至37℃,KGM/XG/β-CD复合凝胶的溶胀度随之增大。     

工艺因素对黄胞胶接枝丙烯酸高吸水性树脂吸水性能的影响

以黄胞胶(XG)、丙烯酸(AA)为主要原料,N,N′-亚甲基双丙烯酰胺(MBAA)为交联剂,过硫酸铵(APS)为引发剂,合成了XG接枝AA高吸水性树脂。通过单因素试验研究了单体配比、中和度、引发剂用量、交联剂用量、反应时间和反应温度等对该树脂吸水性能的影响,采用正交试验法优选出最佳制备工艺条件,并对接枝共聚物的结构进行了表征。结果表明:影响树脂吸水性能的主要因素是引发剂用量、单体配比和交联剂用量;最佳制备工艺条件为m(AA)∶m(XG)=6∶1,AA中和度为60%,w(交联剂)=0.4%和w(引发剂)=1.0%(均相对于XG而言),反应温度为60℃;在此工艺条件下制取的树脂,其最大吸水倍率为904g/g;接枝共聚物在1630cm-1处出现C=O特征吸收峰,说明AA已成功接枝在XG链上。     

均匀设计法优化一种高吸水性树脂的制备工艺

采用水溶液聚合的方法制备了黄原胶接枝丙烯酸/2-丙烯酰胺基-2-甲基丙磺酸[XG/P（AA-AMPS）]高吸水树脂。采用U10*（104）均匀设计对合成工艺进行优化,得出最佳合成条件为丙烯酸用量12 g、引发剂用量为单体总量的0.5%、丙烯酸的中和度为80%、聚合反应温度60 ℃。最佳合成条件下制备的高吸水性树脂吸水倍率达997.1 g/g,吸生理盐水倍率为176.2 g/g。采用傅里叶红外光谱（FTIR）、扫描电镜（SEM）和综合热分析仪对高吸水树脂进行表征。红外光谱分析结果显示丙烯酸（AA）和2-丙烯酰胺基-2-甲基丙磺酸（AMPS）已接枝到黄原胶分子链上,扫描电镜观察结果显示树脂形成一种多孔性网络结构,热性能分析结果显示树脂在高温下具有良好的热稳定性。     

Synthesis and Characterization of Poly(acrylic acid)/Poly(vinyl alcohol)-xanthan Gum Interpenetrating Network (IPN) Superabsorbent Polymeric Composites

Initially interpenetrating network (IPN) hydrogel was prepared by dispersing xanthan gum (XG) into poly(vinyl alcohol) (PVA) backbone in an aqueous medium. Polyacrylic acid (PAA)/Poly (vinyl alcohol)-Xanthan gum IPN superabsorbent composite were fabricated well by dispersing the prepared IPN hydrogel in acrylic acid and polymerized in a complete aqueous environment through chemical cross-linking method. These superabsorbent polymeric composites were analytically evaluated by scanning electron microscopy (SEM), Fourier Transform Infrared Spectra (FTIR), Thermal analysis (DSC) and X-ray diffraction (XRD) analysis. Simultaneously water absorbency, swelling kinetics and water retention abilities of this prepared superabsorbent polymeric composites were also investigated systematically.     

一种耐盐型高吸水性树脂的制备及其性能研究

以过硫酸铵(APS)为引发剂,N,N’-亚甲基双丙烯酰胺(MBAA)为交联剂,采用水溶液聚合法,制备了黄原胶(XG)接枝丙烯酰胺(AM)耐盐型高吸水性树脂,采用单因素和正交分析法考察了丙烯酰胺用量、碱用量、聚合温度、交联剂和引发剂用量等因素对树脂性能的影响。实验表明,当m(AM)∶m(XG)=6∶1,m(NaOH)∶m(AM)=1∶1,聚合温度为60℃,m(MBAA)∶m(AM)=0.04∶1,m(APS)∶m(AM)=0.07∶1时,所得树脂对去离子水的吸收倍率可达1 457 g/g,对0.9%NaC l溶液的吸收倍率可达623 g/g,且吸收速率适中,保水性能良好,是一种耐盐型高吸水性树脂。     

响应曲面法优化XG/AM接枝共聚物的合成工艺

为优化黄原胶(XG)与丙烯酰胺(AM)接枝共聚物(XG-g-AM)的合成工艺,以产品接枝率、接枝效率的回归综合得分为指标,采用响应曲面(RS)法分析了m(AM)∶m(XG)比例、XG浓度和辐射总剂量(60Co-γ为辐射源)对产物接枝参数的影响,并建立了相应的预测模型;同时利用元素分析、红外光谱(FT-IR)和X射线衍射(XRD)法对接枝产物的结构进行了表征。结果表明:AM已成功接枝在XG上,并且当m(AM)∶m(XG)=2.9∶1、XG浓度为9.8 g/L和辐射总剂量为5.9 kGy时,相应产品的接枝率、接枝效率回归综合得分的预测值(19.95)最大;验证了最佳工艺条件下制备的产品接枝率为130.2%,平均接枝效率为80.4%,综合得分为19.78,试验值与预测值吻合较好,说明该模型可以较好地反映综合得分与各影响因素之间的关系。     

Rheological and drag reduction properties of hydroxypropyl xanthan gum solutions☆

Hydroxypropyl xanthan gum (HXG) was prepared from xanthan gum (XG) and propylene oxide under alkaline condition. Rheological and drag reduction properties of different concentrations of aqueous HXG and XG solution were studied. The micro-structure network of HXG and XG solutions was investigated by Cryo-FESEM. The re-sults showed that HXG and XG solutions could exhibit shear thinning property. The apparent viscosity of 6 g·L?1 HXG solution was 1.25 times more than that of 6 g·L?1 XG solution. The storage modulus G′and the loss modulus G″of HXG solutions were greater than those of XG solutions, and thixotropic and viscoelastic prop-erties were more significant in HXG solutions. The HXG and XG solutions reduced the pressure drop of straight pipe, and the maximum drag reduction of 1 g·L?1 HXG and XG in smooth tube reached 72.8%and 68.1%, respec-tively. Drag reduction rate was increased as the concentration increased. The HXG solution may become a new polymeric drag reducer.     

A novel route for synthesis of cross-linked polystyrene copolymer beads with tunable porosity using guar and xanthan gums from bioresources as alternative synthetic suspension stabilizers

Cross-linked polymer beads with different cross-linking agent loading were prepared by carrying out cross-linking suspension copolymerization of styrene-divinylbenzene (St- DVB) monomers using guar gum (GG) and xanthan gum (XG) from bioresources as eco-friendly suspension biopolymer stabilizers in the presence of non reactive diluents. The effects of GG and XG as suspension biostabilizers on the characteristics of the styrene copolymer beads were investigated regarding thermal properties, porosity characteristics, solvent swelling ratio, and surface morphologies using TGA, DSC, XRD, SEM, BET analyses. Spherical and regular beads with smooth surface were produced and the average particle size was in the range 170–290 μm (50–80 mesh size). The porosity characteristics of the produced beads including surface area and pore volume were in range 0.45 m²/g and 32–45 ml/g, respectively. Overall, the present article provided a novel route to prepare cross-linked polystyrene copolymer beads with tunable porosity suitable for catalyst support.     

黄原胶改性制备高吸水性树脂的研究

以丙烯酸(AA)和丙烯酰胺(AM)为黄原胶(XG)的接枝改性剂,采用反向悬浮聚合法制备了高吸水性树脂——接枝改性共聚物(XG-g-AA/AM)。采用U*10(104)均匀设计法对XG-g-AA/AM的合成工艺进行了优化。结果表明:XG-g-AA/AM的最佳合成条件为m(AA)=10.0 g、w(引发剂)=0.5%(相对于单体总质量而言)、AA中和度80%和反应温度60℃,此时XG-g-AA/AM的吸水倍率为890.1 g/g、吸盐水倍率为172.2 g/g;热失重分析(TGA)结果显示,XG-g-AA/AM的热稳定性优于XG;扫描电镜(SEM)观测结果显示,XG-g-AA/AM表面形成的多孔网络结构,有利于其对水分子的接触与吸附。     

丙烯酰胺黄原胶接枝共聚物水溶液粘性行为研究

以丙烯酰胺（AM）、黄原胶（XG）为主要原料,硝酸铈铵（CAN）为引发剂,合成了丙烯酰胺黄原胶接枝共聚物（XGA）,研究了无机盐（NaCl、CaCl2、MgCl2）浓度、温度、老化时间和剪切速率等因素对XGA溶液黏性行为的影响。结果表明,XGA具有与XG相同的优良的耐盐性能,XGA溶液的黏度在高温（85℃）下具有更好的时间稳定性;XG和XGA溶液的流变曲线均表现为宾汉流体的流变行为,当剪切速率由最大值逐渐减小时,溶液黏度逐渐恢复,但与初始黏度相比存在滞后现象。     

黄原胶/膨润土复合高吸水性树脂的制备与性能研究

采用水溶液聚合法制备了黄原胶(XG)/膨润土有机-无机复合SAP(高吸水性树脂)。通过单因素试验法和正交试验法优选出制备复合SAP的最佳工艺条件。结果表明:丙烯酸(AA)、丙烯酰胺(AM)、XG与膨润土之间发生了接枝共聚反应;当m(AA)∶m(AM)=5∶1、AA中和度为75%、w(膨润土)=5%、w(引发剂)=1.0%和w(交联剂)=0.08%时,相应的复合SAP具有最大的吸水倍率(863.8 g/g)和吸盐水倍率(109.4 g/g)。     

Stiffness xanthan hydrogels: synthesis,swelling characteristics and controlled release properties

Summary  New xanthan hydrogels were synthesized at 90 C in water acid media using adipic acid dihydrazide (ADH) as crosslinking agent, in the presence of 1-ethyl-3[3-dimethyl amino] propyl carbodiimide hydrochloride (EDCI) as reagent. In these conditions, xanthan chains are in a predominantly helical conformation and through rheological measurements the influence of the temperature over the helix-coil transition was assessed. Xanthan hydrogels with different concentration in polysaccharide and ADH were obtained and characterised by elemental analysis and swelling properties. High concentration of xanthan (i.e. 25gL^-1) is needed to obtain gel due to the low available carboxylic functions in the helical conformation. During the swelling analysis, it was noted that high temperature (i.e. 90 C) favoured the conformational transitions within the network. The drug loading and releasing properties were estimated using methylene blue as model molecule and different experimental pH and ionic strength conditions.