壳聚糖/聚乙烯醇水凝胶的硬度研究

探讨了壳聚糖/聚乙烯醇水凝胶的制备方法,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水凝胶硬度的影响.正交实验结果表明当聚乙烯醇与壳聚糖质量比为6、溶剂醋酸体积为80mL、交联剂戊二醛浓度为0.426mol/L时,凝胶硬度为132.643kPa.凝胶硬度随着聚乙烯醇与壳聚糖质量比和交联剂戊二醛浓度的增大而增大,随着溶剂醋酸溶液体积的增加而减小,随着凝胶温度的升高先增大后减小,壳聚糖/聚乙烯醇凝胶硬度随着放置时间的延长而逐渐增大,PVA-124与壳聚糖制备的凝胶硬度最大.     

阳离子丙烯酸酯共聚物表面活性剂的结构及溶液性能

通过自由基溶液共聚合法合成了无规型阳离子丙烯酸酯共聚物表面活性剂,利用红外光谱(FT-IR)和核磁共振谱(1H-NMR和13C-NMR)对聚合产物的结构和组成进行了表征,考察了浓度、温度等对聚合物丙酮溶液的增比黏度和聚合物水溶液表面张力的影响。结果表明,聚合物丙酮溶液的增比黏度随溶液浓度增加总体呈现上升趋势,在相同溶液浓度下,其增比黏度随温度升高呈先降低后升高再降低的趋势;聚合产物可将水溶液的表面张力降低到43mN/m,其临界胶束浓度为0.8 g/L;聚合物水溶液的表面张力随温升高而降低,且随溶液pH值增大而增大。     

高性能PVC/PSf共混超滤膜的研制——(Ⅰ)稀溶液黏度法测PVC/PSf共混相容性的研究

首次采用稀溶液黏度法(DSV法),通过相对黏度-组成曲线、增比黏度-浓度曲线,以及值对PVC与PS f的相容特性进行了研究。结果表明,PVC/PS f共混体系为部分相容体系,体系相容性随PVC/PS f共混比的增大而增加;溶液浓度和温度对PVC/PS f体系的相容性存在一定的影响。     

混合溶剂中聚丙烯腈纺丝原液的可纺性

以二甲基亚砜/二甲基乙酰胺(DMSO/DMAc)为混合溶剂,选择高黏均分子量(Mη)聚丙烯腈(PAN)为研究对象,系统研究了温度、溶剂比例、分子量、固含量对混合溶剂纺丝原液流变性的影响。结果表明,纺丝原液的表观黏度随分子量、固含量的增大而增加,随温度升高而降低,随溶剂比例先增加后减小,在V(DMSO)∶V(DMAc)=1.25∶1处出现最小值,随后逐渐增加。PAN的结晶度随溶剂体积比增大而升高,在1.25∶1时结晶性能最优。最终实验确定PAN纺丝原液可纺性最佳条件为:纺丝温度60℃～70℃,溶剂体积比1.25:1,固含量14%～16%。     

不同中和度聚丙烯酸水溶液的黏度行为

测定了不同中和度聚丙烯酸水溶液的黏度,结果表明,在中和度为0.25时聚丙烯酸水溶液比浓黏度出现最大值。进一步测定了中和程度分别为0.04和0.09、以及没有经过中和的聚丙烯酸水溶液比浓黏度的浓度依赖性,发现存在着两个特征的浓度C1和C2。当溶液的浓度小于C1时,高分子溶液的比浓黏度保持恒定;当溶液的浓度大于C1时,高分子溶液的比浓黏度随着浓度的增加而增加。当溶液浓度达到C2时高分子溶液比浓黏度对浓度作图再次出现转折,此时进一步增加溶液的浓度,高分子溶液比浓黏度虽然继续增加,但是增加的梯度有所下降。高分子溶液比浓黏度的浓度依赖性与溶液中高分子内和高分子之间相互作用密切相关。     

超临界流体辅助醋酸纤维素溶液加工的流变性能

为了改善二醋酸纤维素(CDA)加工的流变性能,采用超临界二氧化碳辅助CDA溶液单螺杆挤出加工,通过狭缝流变仪进行流变测试,研究了注入超临界二氧化碳和加工条件(挤出温度、溶剂含量)对CDA溶液流变行为的影响。结果表明,CDA溶液和CDA/CO_2溶液体系均是非牛顿假塑性流体;CDA溶液和CDA/CO_2溶液体系的剪切黏度随着挤出温度或溶剂量的增加而降低;注入超临界二氧化碳显著降低了CDA溶液的黏度、挤出温度、剪切黏度对温度的敏感程度、口模压力和溶剂量,提高CDA溶液的挤出流量和非牛顿指数。随着温度升高,6 r/min和8 r/min时CDA/CO_2溶液体系黏度下降值大,黏度降低值可以达到47.93%;同一溶剂含量下,6 r/min时注入超临界二氧化碳后CDA溶液黏度下降值较大,降低值可以达到48.10%。     

羟乙基纤维素溶液的触变性与反触变性

对于高分子流体流动特性的研究不仅能够判断该流体的应用价值,而且还可以用于分析流体内部的结构特点和结构演变过程,建立流体的结构与性能关系.以羟乙基纤维素(HEC)为研究对象,研究了HEC在水-乙醇和水-乙二醇溶液体系中的流动性质.结果表明,HEC/水-乙醇溶液会发生从触变性到反触变性的转变,溶液稳态黏度随着乙醇体积分数的增加先升后降;HEC/水-乙二醇溶液的流动特性更加复杂,虽然也会发生从触变性到反触变性的转变,但是,相对低浓度的HEC溶液的稳态黏度随乙二醇体积分数的增加线性增长,而相对高浓度的HEC溶液的稳态黏度却在乙二醇体积分数为15％和40％处出现两个极大值.结果表明:在体系中引入乙醇和乙二醇后,由于非溶剂效应以及两种醇分子与HEC分子间的氢键作用,使得HEC在溶液中产生了不同的聚集状态,该聚集状态在持续剪切的作用下又不断发生改变,从而影响了溶液的流动性质.     

PTFE/PA6和PTFE/PA66共混物的吸水性及流变行为

通过浸水实验、缺口冲击断裂实验和动态流变测试,考察了PTFE含量对PTFE/PA6和PTFE/PA66共混物的吸水率、冲击断裂强度及熔体黏度的影响以及熔体黏度随温度和频率的变化规律。结果表明,PTFE/PA6和PTFE/PA66共混物的吸水率均随着PTFE含量的增加而减小,即PTFE的加入抑制了共混物的吸水性。两种共混物的冲击强度比纯PA明显降低,但是吸收水对两种共混物冲击强度的影响不显著。随着PTFE含量的增加,共混物熔体的黏度先减小后增加,说明适量的PTFE可以改善共混物的成型加工特性。共混物熔体的黏度随加载频率的增大而降低,符合假塑性流体流动规律。有趣的是,对于PTFE/PA6共混物的黏度随着温度的升高而减小,而PTFE/PA66共混物黏度随着温度升高近似成指数规律增大。     

高分子量微生物纤维素LiCl/DMAc纺丝溶液流变性研究

微生物纤维素溶液流变性能对其纺丝工艺研究具有重要的指导意义,以8%LiCl/DMAc为溶剂采用旋转流变仪对不同分子量、不同固含量溶液的稳态流变及动态流变进行了测定。结果表明:微生物纤维素的LiCl/DMAc溶液属于非牛顿假塑性流体;高分子量的溶液比低分子量的溶液黏度要高;随温度的升高,溶液表观黏度不断下降,高浓度的溶液在低剪切速率下对温度更敏感,且浓度越高,结构黏度指数越大,纺丝难度越大。通过动态流变得知,溶液浓度越高,体系弹性强度及黏滞力越大,但对外部剪切力越敏感,其物理稳定性越弱。     

壳聚糖／羧甲基纤维素聚电解质络合物膜的乙醇／水渗透汽化性能研究

采用壳聚糖和羧甲基纤维素进行聚离子反应．制备聚电解质络合物膜。该膜用于乙醇／水的渗透汽化分离，显示具有优先透水性，在乙醇浓度90％，温度60℃下，渗透通量和分离系数分别达197g／m2·h，1588。随料液乙醇浓度的增加，膜渗透通量下降，而分离系数增加，分离系数在乙醇浓度90％左右有一极大值。随温度升高，膜渗透通量和分离系数同步上升，渗透通量随温度的关系符合Arrhe－nius方程，渗透汽化表现活化能为34kJ／mol。     

小麦醇溶蛋白膜力学性能与吸湿性研究

采用小麦醇溶蛋白的乙醇/水(70/30(v/v))溶液制备了醇溶蛋白膜,分析了交联剂用量与pH值对膜的拉伸性能、吸水性及透湿性的影响.结果表明,适度交联的醇溶蛋白膜具有最大拉伸强度与较高的断裂伸长率.随交联剂用量增加,膜的吸水率稍有下降,而透湿性显著增大.酸碱处理能显著提高膜的拉伸强度,但使吸水性稍有增大.     

烯丙基咪唑离子液体的合成与溶液性能

室温离子液体氯化1-烯丙基-3-甲基咪唑被合成,利用质谱和NMR对其结构进行了表征。该离子液体与水或乙醇的二相混合液在293.2K的粘度被测定并计算了该混合体系的过量粘度,建立了过量粘度与水或乙醇的摩尔分数的关系。另外,电导率随组分及温度的变化以及电导活化能也被测定,溶液的电导率随温度的升高及溶剂量的增加而增大。     

Preparation, physical properties, and stability of gambogic acid-loaded micelles based on chitosan derivatives

The objective of this study is to find out an optimized formulation of water insoluble anticancer drug gambogic acid (GA)-loaded chitosan derivatives micelles. After preliminary test, four factors (the amount of N-octyl-O-sulfate chitosan (AOSC), the amount of GA, volume of ethanol, and dialysis temperature) and three levels for each factor that might affect the formation of micelles were selected and arranged in L₉ (3⁴) orthogonal experimental design to optimize the formulation of GA-loaded micelles. To compare each of the micellar formulations quantitatively, an overall desirability function was defined and calculated based on three assessment indices (drug content, loading efficiency, and entrapping efficiency of micelles). The optimized formulation was 8 mg of GA dissolved in 0.3 mL of ethanol, 12 mg of AOSC dissolved in 2 mL of H₂O, respectively. The drug solution and blank micellar solution were mixed, followed by dialysis against water at 25°C. The mean size of micelle was 100 nm approximately. Lyophilized samples could keep stable for at least 2 months when it was stored at 4°C. These data suggest that the amphiphilic chitosan derivative may improve the water solubility of GA and thus be used as its nano-carrier.     

Electrospinning of collagen-chitosan complex

The collagen-chitosan complex nanofibers have been prepared for the first time by electrospinning. The mixed HFP/TFA (the volume ratio of 90/10) was found to be the appropriate solvent for electrospinning. The concentration of the spinning solution and the ratio of chitosan/collagen were varied and adjusted to get smooth nanofibers. It was found that the diameter of the spun fibers became thick with the concentration of the solution increasing and became fine with the ratio of the chitosan/collagen increasing. We have characterised the molecular interactions in collagen-chitosan complex by Fourier transform infrared spectroscopy. The spun fibers are designed to mimic the native extracellular matrix for tissue engineering and to develop functional biomaterials.     

Nano-sized α and β-TCP powders prepared by high temperature flame spray pyrolysis

Nano-sized α-TCP powders with spherical shape and non-aggregation characteristics were directly prepared by high temperature flame spray pyrolysis from the mixed spray solution of water and ethyl alcohol. The α-TCP powders prepared from the aqueous spray solution without ethyl alcohol had a bimodal size distribution with nanometer and micron sizes. Nano-sized and monodisperse α-TCP powders were prepared when the volume ratio (ethyl alcohol/distilled water, V/V) in the mixed solvent was of 40/60. The mean size of the nano-sized α-TCP powders was 32 nm. The composition ratio of calcium and phosphorous components of the nano-sized α-TCP powders was 1.49. The mean size of the spherical-like powders post-treated at a temperature of 600 °C was 57 nm. The mean size of the powders increased with increasing the post-treatment temperatures. The phase of α-TCP powders prepared by flame spray pyrolysis did not change at post-treatment temperatures below 700 °C. On the other hand, the powders post-treated at temperatures of 800 and 900 °C had single β phase of TCP.     

Preparation,Physical Properties,and Stability of Gambogic Acid-Loaded Micelles Based on Chitosan Derivatives

The objective of this study is to find out an optimized formulation of water insoluble anticancer drug gambogic acid (GA)-loaded chitosan derivatives micelles. After preliminary test, four factors (the amount of N-octyl-O-sulfate chitosan (AOSC), the amount of GA, volume of ethanol, and dialysis temperature) and three levels for each factor that might affect the formation of micelles were selected and arranged in L₉ (3⁴) orthogonal experimental design to optimize the formulation of GA-loaded micelles. To compare each of the micellar formulations quantitatively, an overall desirability function was defined and calculated based on three assessment indices (drug content, loading efficiency, and entrapping efficiency of micelles). The optimized formulation was 8 mg of GA dissolved in 0.3 mL of ethanol, 12 mg of AOSC dissolved in 2 mL of H₂O, respectively. The drug solution and blank micellar solution were mixed, followed by dialysis against water at 25°C. The mean size of micelle was 100 nm approximately. Lyophilized samples could keep stable for at least 2 months when it was stored at 4°C. These data suggest that the amphiphilic chitosan derivative may improve the water solubility of GA and thus be used as its nano-carrier.     

溶液浓度和非溶剂比例对PVC膜形貌和疏水性能的影响

目的 研究溶液质量分数和非溶剂体积分数对PVC薄膜表面形貌和疏水性能的影响,以获得具有超疏水表面的PVC薄膜。方法 以四氢呋喃为良溶剂、乙醇为非溶剂,利用非溶剂诱导相分离的原理,采用旋涂法在玻璃基底上制备超疏水的聚氯乙烯（PVC）涂膜;通过对PVC样品的疏水性、表面形貌、结晶性能和热性能进行分析,探究溶液质量分数以及非溶剂的体积分数对PVC样品性能的影响。结果扫描电镜和接触角测试表明,添加一定体积分数的乙醇使得所制备的PVC样品形成了多孔膜层以及纳米级聚合物球粒,从而提高了PVC样品的疏水性。XRD测试结果表明,添加乙醇并不会改变PVC样品的无定形结构。结论 PVC溶液质量分数对所制备PVC样品的疏水性能和表面结构没有明显影响,乙醇体积分数为30%～40%时,可形成表面水接触角大于150°的超疏水表面。     

胶原溶液流变性能的研究

以纯化猪皮为原料提取胶原,配制不同浓度胶原溶液研究其流变性能,采用幂律方程拟合流动曲线,拟合程度非常高,以黏流活化能分析了黏度对温度的依赖性。讨论了胶原溶液浓度、剪切速率、温度对其黏度的影响。结果表明,该胶原溶液具有假塑性流体特征,浓度越高,非牛顿指数n越小,假塑性越强,黏度随剪切速率增大而下降的程度越明显。相同剪切速率下,温度升高,各浓度胶原溶液黏度下降。浓度越高,黏流活化能越大,对温度越敏感。     

Mechanical and Water Vapor Transmission Properties of Polysaccharide Films

The film-forming properties of chitosan, chitosan glutamate, sodium alginate, and hydroxypropyl methylcellulose (HPMC) were investigated. Films were produced by a casting/solvent evaporation method from plasticizer-free and plasticizer-containing aqueous solutions. The water vapor transmission and mechanical properties (puncture strength and % elongation) of the films were investigated as a function of the polymer type and viscosity, plasticizer type (glycerin, propylene glycol, polyethylene glycol, triethyl citrate), plasticizer concentration, and type and concentration of acid used to dissolve chitosan. The effect of storage humidity was also examined. Glycerin and water were good plasticizers for chitosan glutamate. The chitosan film properties were dependent on the type and concentration of acid used to dissolve it, citric acid being a good plasticizer. The mechanical and water vapor transmission properties of alginate and HPMC films were less influenced by the investigated variables.     

不同条件对PVA/CS复合水凝胶溶胀性能的影响

以聚乙烯醇(PVA)、壳聚糖(CS)为原料,戊二醛为交联剂,制备出PVA/CS复合水凝胶载体材料,改变PVA/CS的质量配比、交联剂含量、pH值和温度,考察了不同条件下对复合水凝胶溶胀性能的影响.结果表明,当PVA/CS质量比为3:1、交联剂体积分数为4%时所合成凝胶的溶胀性能较好;随着温度的升高,溶胀度不断减小;凝胶在酸性条件的溶胀性能远远优于碱性条件的溶胀性能.