L-聚乳酸/低分子量壳聚糖共混膜的制备和特性

二甲基亚砜(DMSO)作为共溶刺，将两种极性不同的生物医用高分子L-聚乳酸(PLLA)与低分子量壳聚糖混合在一起．扫描电镜(SEM)研究结果表明两种组分共混时存在着明显的相分离．当壳聚糖含量在2％以内时，壳聚糖相在共混膜中呈现空心圆状的图案，空心圆的直径为几微米．PLLA用DMSO溶解后，在重新干燥的过程中，PLLA的堆积结构会发生变化，它的玻璃化转变温度由55.5℃变为34℃．共混膜中混入的壳聚糖含量在2％以内时，在保持的聚乳酸的力学性能的同时。可以降低聚乳酸的接触角。改善聚乳酸的亲水性．     

低分子量N,O-羧甲基壳聚糖的合成及吸湿保湿性能

采用不同反应温度、反应时间和低分子量壳聚糖与氯乙酸摩尔比,在非均相反应体系中合成了不同取代度的低分子量N,O-羧甲基壳聚糖。当反应温度为60°C,反应时间为4h,低分子量壳聚糖与氯乙酸投料比为1∶1.5时,目标产物的取代度可达71%。吸湿保湿性能测定表明:取代度越大,低分子量N,O-羧甲基壳聚糖的吸湿保湿性越好,在相对湿度为81%,取代度从27%增大到71%时,其吸湿性从32.14%增大到37.27%,保湿性从310.72%增大到348.69%。     

水溶性壳聚糖的制备与应用

水溶性壳聚糖的制备与应用赵文伟，于黎，钟晓光，张月芳，孙家珍（中国科学院长春应用化学研究所，长春１３００２２）壳聚糖（ｃｈｉｔｏｓａｎ，（１，４）－２－胺基－２－脱氧－β－Ｄ－葡聚糖）是由甲壳素（ｃｈｉｔｉｎ，（１，４）－２－乙酰胺基－２－２脱氧－β...     

低分子量N-羧丁酰壳聚糖的合成及其吸湿保湿性

低分子量N-羧丁酰壳聚糖的合成及其吸湿保湿性;低分子量壳聚糖;低分子量N-羧丁酰壳聚糖;吸湿性;保湿性     

低碱法制备羧甲基壳聚糖及表征

低碱法制备羧甲基壳聚糖及表征;壳聚糖;羧甲基壳聚糖;取代度;特性粘度;低碱法     

低分子量溴代聚苯乙烯的制备及应用

用溶液法合成了一系列低分子量的聚苯乙烯，其溴化产物（Ｂｒ－ＰＳ）的溴含量和热稳定性与美国同类产品Ｐｙｒｏ－Ｃｈｅｋ ＬＭ相当，分别用作聚苯乙烯树脂的阻燃剂，极限氧指数测定结果表明，其阻燃性也达到了Ｐｙｒｏ－Ｃｈｅｋ ＬＭ的水平。     

甲壳素类液晶高分子研究--低分子量壳聚糖溶致液晶性及分子量对液晶临界浓度的影响

研究了两种用酶降解法得到的低分子量壳聚糖样品(CS1和CS2)的溶致液晶性.用GPC并辅以质谱法确定了两样品的数均相对分子质量为622和2311 g/mol.在相对分子质量低至622的低分子量壳聚糖(相当于四糖)水溶液中仍发现了溶致液晶现象,并确定出相对分子质量为622和2311的低分子量壳聚糖液晶临界浓度为73%和36%(W/W%),这些结果与已报道的中、高分子量壳聚糖液晶临界浓度随分子量升高而降低的基本规律是一致的.实验结果与经典的KS理论预测值不符,因为低分子量壳聚糖的相对分子质量超过了KS理论对高分子临界浓度的预测范围.     

低分子量壳聚糖的Sm3+配合物的合成和表征

壳聚糖经双氧水降解制得低分子量壳聚糖,低分子量壳聚糖与Sm3 反应制得配合物。分别用红外、紫外、荧光等测试手段对低分子量壳聚糖及其与Sm3 形成的配合物的结构和性能进行了表征。结果表明,低分子量壳聚糖与Sm3 发生了螯合作用,形成了较稳定的配合物。     

低分子量聚丙烯酰胺研究进展

综述了低分子量聚丙烯酰胺的合成方法及应用研究进展,同时对其未来的发展方向进行了展望.     

水溶性低分子壳聚糖的制备

Oxidative degradation of chitosan by H2O2-NaClO mixed oxidant is studied in acidic condition.The effects of concentration of H2O2,reactive temperature and reaction time on oxidative degradation reaction are studied.The results show that the method of oxidative degradation of chitosan with H2O2-NaClO mixed oxidant is effective for preparation of water-soluble chitooligosaccharides.     

Investigation of the Interactions in Complexes of Low Molecular Weight Chitosan with Ibuprofen

Complexation between ibuprofen and low molecular weight chitosan (LMWC) was studied. LMWC was prepared from high molecular weight chitosan using the acid hydrolysis method. The complexes were investigated by using DSC, FT-IR and liquid-state ¹H-NMR. Molecular mechanics (MM) calculations were used to give insight into the stoichiometry of the interaction of chitosan with ibuprofen. The results showed that complexation of ibuprofen with LMWC involves ionic interaction between the ammonium group of LMWC and the carboxylate anion of ibuprofen. It was also shown that it is more efficient to prepare the complexes using lower concentration solutions of the polymer. These results were supported by molecular mechanics calculations. The experimental results may explain the discrepancies in the literature where, in many studies, the concentration of chitosan and its low average molecular weight were not considered to be important factors in the complexation process.     

低分子肝素/壳聚糖/海藻酸钠复合微囊的制备及释药性能

低分子肝素/壳聚糖/海藻酸钠复合微囊的制备及释药性能;壳聚糖; 海藻酸钠; 低分子肝素; 微囊; 释药性能     

超高分子量聚乙烯的研发及应用

超高分子量聚乙烯(UHMWPE)是一种性能卓越的工程塑料,同众多的聚合材料相比,具有其它工程塑料所无法比拟的耐冲击性、耐磨损性、耐化学药品性、耐低温性、耐应力开裂性、抗粘附能力,优良的电绝缘性、自润滑性及安全卫生等性能,可以代替碳钢、不锈钢、青铜等材料广泛地应用于体育、纺织、采矿、化工、包装、建筑、机械、电气、医疗等领域。本文综述了国内超高分子量聚乙烯生产现状、需求、产品加工和应用情况,并对其以后的发展前景进行了预测。     

低聚壳聚糖降解制备、分离、纯化、鉴别的研究进展

查阅了近十年来国内外有关壳聚糖降解的最新文献,系统地综述了壳聚糖降解制备、分离、纯化、鉴别的研究进展。     

低温等离子体对超高分子聚乙烯纤维表面改性研究

介绍了低温等离子放电技术的概念、原理、实施方法及其在超高分子量聚乙烯（UHMWPE）纤维表面改性方面的应用。综述了国内外低温等离子体对UHMWPE纤维表面改性的最新研究成果,阐述了气体等离子体种类、处理功率和处理时间等因素对UHMWPE纤维表面改性效果的影响机理,以及低温等离子设备对UHMWPE纤维表面改性连续化的初步...     

小分子与高分子混合凝胶研究进展

凝胶作为一种半固态的软物质材料近年来得到很多关注。高分子和小分子都可以作为凝胶的胶凝剂,但是由于在形成过程中两者形成的结构交联与否对形成的凝胶影响很大,表现出了明显的不同。而小分子高分子混合凝胶能整合两者的优势,使混合凝胶兼具小分子凝胶的刺激响应性和高分子凝胶的力学性能。本文从高分子凝胶与小分子凝胶的差异化和互补性方面入手,总结了小分子和高分子的混合凝胶的研究进展。     

血清中低分子量蛋白质的提取和鉴定

采用改进的圆盘凝胶电泳提取人血清中低分子量蛋白质, 去除了血清中分子量大于3×104的蛋白质, 将提取的低分子量蛋白质热变性后直接在溶液中酶解成肽, 经液相色谱-质谱分析, 并进行Mascot数据库检索, 确认出人血清中97种蛋白质.     

Progress in Molecular Dynamics and Hansen Solubility Parameters of Low Molecular Weight Gels北大核心CSCD

Recently,the use of computational methods such as Molecular Dynamics（MD）simulations and Hansen Solubility Parameters （HSPs）to study the behavior of small molecule gelators has attracted much attention. MD simulation is a computational method based on classical mechanics and is one of the preferred techniques for understanding the process of small molecule gelators. The MD simulation can more accurately analyze the gelation trend or assembly behavior of small molecule gelators,dynamically and graphically display the self-assembly process,effectively reveal the relationship between the structure of small molecule gelators and related gelation behavior,and quantitatively analyze non-covalent bond interactions such as hydrogen bonds,π-π stacking,van der Waals interactions,ionic bonding and solvophobic interactions. By performing molecular dynamics simulations on known gelators/non-gelators,parameters related to gelation behavior in the simulated data are extracted,and the linear correlation is measured by fitting the Pearson correlation coefficient to finally predict the gelation behavior of a certain class of small molecules. On the other hand,the empirical model developed according to the HSPs is the most representative,which consists of the energy of dispersion interaction（δd）,the energy of polar interaction（δp）and H-bonding energy（δh ）between molecules. These three parts determine the coordinate point of the three-dimensional space（Hansen space）. According to the range of the point,it can be determined whether the organic small molecule can form a gel in a specific solvent. In this paper,representative works published recently in the field of organic small molecule gels by using MD simulations and empirical models are reviewed. Some comments on the assembly behavior of gelators,the regulation and prediction of non-covalent bond interactions on gelation ability are made. © 2022, Science Press (China). All rights reserved.     

Review: Preparation and Application of Magnetic Chitosan Derivatives in Separation Processes

Chitosan is one of the most abundant natural polysaccharide in nature. Due to its unique properties, chitosan has fascinated the scientific community since its discovery. When modified with other materials and combined with magnetic particles, the resulting composite material, a magnetic chitosan derivative, is provided with three significant characteristics. First, chitosan has excellent properties for preconcentration/extraction, such as adsorption and chelating effects, low cost, and nontoxicity. Second, new functional groups have enhanced the properties of chitosan that include water solubility, stability, recyclability, and enhanced adsorption capacity. Finally, due to the efficient and fast adsorption processes, as well as simple and convenient magnetic separation, the magnetic adsorbents greatly reduce the time of sample handling. In this article, recent synthesis and modification methods of magnetic chitosan derivatives are reviewed along with some applications in analytical separations.