甲壳素酰化改性的研究进展

甲壳素作为一种来源广泛的生物质材料,具有良好的生物相容性和抑菌性,可用于药物缓释、伤口包覆、组织植入、生物分离、重金属吸附等高附加值领域,但强烈的氢键作用使其不熔难溶,需经改性以促进其加工和应用。本文简要回顾了甲壳素酰化改性的发展历程,重点介绍均相条件下甲壳素的各种酰化方法,如在甲磺酸、氯化锂/二甲基乙酰胺、离子液体、三氟乙酸酐中进行反应,以及在非均相条件下提高酰化效率的各种方法,如优选催化剂、结构活化等,比较了各种方法的优缺点,并简述了甲壳素酰化产物的性能特点和应用。目前甲壳素非均相酰化工艺较成熟,已实现工业化,但仍有一定的局限性和缺点。最后展望了均相和非均相酰化可能的改进方向。     

微波辅助合成醋酸丁酸纤维素的研究

以精制棉、正丁酸、冰醋酸等为原料,浓硫酸为催化剂,采用微波辅助的方法合成了醋酸丁酸纤维素（CAB-381）。用化学分析方法对产物的丁酰（乙酰）基值进行测定,结果表明：微波辅助合成的CAB-381和美国伊士曼公司的产品CAB-381的丁酰基值和乙酰基值比较接近,分别为38.0和37.7、13.5和13.6;红外谱图也基本一致。在微波辅助的作用下,加快了酰化的反应速度,缩短了反应时间。与传统方法相比,产品的丁酰值提高了9.8%,产品产率高出11.97%。     

甲壳素和壳聚糖的化学改性及其应用

介绍了甲壳素和壳聚糖化学改性的研究进展。重点讨论了酰化、羧基化、醚化、Ｎ－烷工经等反应，以及这些衍生物的各领域的应用前景。     

2-乙酰基-4-正丁酰胺基苯酚的合成工艺改进

以对氨基苯酚为原料．经氨基丁酰化,苯酚乙酸酯化,Fries重排,合成了有内在活性的β1肾上腺素受体阻断药醋丁洛尔的关键中间体2-乙酰基-4-正丁酰胺基苯酚,总收率达56．8％．在关键的Fries重排反应中添加惰性无机盐氯化钠为助溶剂,使反应能够顺利进行。     

3,4,5-三甲氧基苯甲酰-3,5-二甲基苯甲酰甲壳素的制备与表征

用共酰化方法制备了3,4,5-三甲氧基苯甲酰-3,5-二甲基苯甲酰甲壳素,获得了一类新型的具有良好溶解性能的高分子紫外线吸收剂.通过元素分析的数据计算了两种酰基的取代度,FTIR表征表明了取代反应的发生,采用X射线衍射和TG等手段对酰化产物的结晶性能和热稳定性进行了研究,通过紫外吸光度的测定计算出两种取代基的摩尔消光系数分别为9329.1 L•mol^-1•cm^-1和652.7 L•mol^-1•cm^-1,并对产物中的酰基进行了定量分析,结果与元素分析结果基本一致.     

甲壳素——壳聚糖的抑菌性能研究进展

甲壳素是一种仅次于纤维素的第二大天然高分子聚合物，是一种可再生资源。记述了目前甲壳素及其脱酰衍生物——壳聚糖的特性以及其在抑菌方面的研究进展。     

甲壳素、壳聚糖的改性研究

综述了甲壳素、壳聚糖的化学改性以及生化改性。着重介绍碱化、酰化、醚化、N-衍生物、酯化等化学改性方法。这样，可增加其在有机溶剂中的溶解，为进一步应用打下基础；还介绍甲壳素衍生物在化妆品、医学和环保方面的应用及在发展过程中存在的一些问题。     

甲壳素-壳聚糖的抑菌性能研究进展

甲壳素是一种仅次于纤维素的第二大天然高分子聚合物,是一种可再生资源。概略的记述了目前甲壳素及其脱酰衍生物?壳聚糖的特性以及其在抑菌方面的研究进展。     

新型除草剂氟丁酰草胺的合成研究

以邻氟三氟甲苯等为初始原料,经硝化、还原、重氮化、水解得到4-氟-3-三氟甲基苯酚,然后与烷基化剂2-溴丁酸乙酯反应,得到2-(4-氟-3-三氟甲基苯氧基)丁酸乙酯,再与苄胺发生酰化反应,得到目标产物氟丁酰草胺,总收率52.3%。     

甲壳素壳聚糖及其衍生物吸湿保湿性研究进展

简要介绍了甲壳素,壳聚糖的物化性质,概述了壳聚糖常见的化学修饰方法,详细综述了甲壳素,壳聚糖及其羟基化化衍生物,羧化衍生物,酰化衍生物的吸湿性和保湿性的研究现状,对β-壳聚糖,甲壳低聚糖的吸湿性和保湿性也进行了介绍。     

Studies upon the fine structure and selected physical and physicochemical properties of butrylchitin membranes

The effect of varying the molecular weight of butyrylchitin membranes cast from methylene chloride on their properties has been investigated. Characterization analyses include X-ray, scanning calorimetry and tensile stress-strain. The crystal structure of the butyrylchitin was shown to consist of fringed micelles, irrespective of the molecular weights examined, and of lower crystal volume fraction than usually found for chitin membranes, 0.3 versus 0.5, respectively. The membranes exhibit greater ductility and less swelling in physiological salt solution with increasing molecular weight. © 1994 John Wiley & Sons, Inc.     

Mixed esters of chitin

One of the main obstacles to the wider application of chitin in polymeric materials is its poor tractability due to unfavorable solubility properties. The solubility can be enhanced by introducing bulky acyl residues into the polymer (as in butyrylchitin and valeroylchitin). However, if modification is carried out with shorter-chain carboxylic acids (as in acetylchitin), the solubility remains poor. By substituting the acetyl residues partially by butyryl residues (mixed ester formation), exclusive use of the bulky carboxylic acids can be avoided and yet good solubility is achieved. These relationships were shown by using high molecular weight mixed chitin esters, prepared with methanesulfonic acid as the solvent and catalyst. The mixed chitin esters, varying both in the overall degree of substitution (1.5-1.9) and the molar ratios of butyryl-to-acetyl residues (1: 0.62 to 1:0.72), were characterized by IR spectroscopy, DSC, elemental analysis, and ¹H-NMR spectroscopy (in trifluoromethanesulfonic acid); the latter allowed the degree of substitution to be determined as well as the moral ratios of butyryl-to-acetyl residues © 1995 John Wiley & Sons, Inc.     

甲壳素/壳聚糖及其衍生物的制备和吸附特性研究进展

综述了甲壳素/壳聚糖的制备方法,并论述了壳聚糖及其衍生物对重金属离子、酸和染料等吸附特性的研究进展.     

甲壳素水解制备氨基葡萄糖盐酸盐的优化工艺条件

采用浓盐酸水解工艺以不同质量(灰分)的甲壳素为原料,制备了氨基葡萄糖盐酸盐,探讨了甲壳素/盐酸质量配比、反应温度和水解时间等因素对产品产率的影响。结果表明,不同灰分的甲壳素水解制备氨基葡萄糖盐酸盐的最佳条件分别为:甲壳素灰分为8%,10%,12%,12%,各原料的甲壳素与盐酸的比(质量比)分别为1∶2.45,1∶2.55,1∶2.7,1∶2.8;反应温度分别为90,92,94,96℃;水解时间分别为4.5,4.8,5,5.3 h;产率分别为92.2%,91.5%,90.2%,89.2%,为工业生产提供了理论基础。     

Investigation of different natural sources of chitin: influence of the source and deacetylation process on the physicochemical characteristics of chitosan

Several sea sources for chitin have been investigated, and the chitin content and crystallographic polymorph of the extracted chitin determined. Deacetylation of the chitin was carried out and the physicochemical characteristics of the resulting chitosan studied. The influence of the reaction parameters (reaction duration, temperature, nature of alkaline reagent, etc) was followed. Thus it became possible to determine adequate reaction conditions for obtaining chitosans with the required properties. The physicochemical characteristics of the obtained chitosan are closely related to the taxonomy of the source. New sea sources for chitin have been investigated and considered for industrial purposes. © 2000 Society of Chemical Industry     

天然高分子静电纺纳米纤维的研究进展

介绍了静电纺丝的原理及利用静电纺丝方法制备天然高分子纳米纤维的最新研究进展,主要介绍了海藻酸钠、天然纤维素、透明质酸、明胶、胶原蛋白、甲壳素及其衍生物等几种主要的天然高分子静电纺纤维的研究进展,并指出它们在生物医学领域的重要应用。     

酸、碱溶液对脱脂蚕蛹的解剖结构影响

将脱脂蚕蛹分别置于清水、1%盐酸溶液和1%氢氧化钠溶液中,100℃浸泡处理20 min,采用电子光学显微分析技术观察脱脂蚕蛹的解剖结构。结果表明:①清水浸泡,蛋白质、甲壳素膨胀;②盐酸溶液浸泡,在蛋白质、甲壳素膨胀的同时,有蛋白的部分分解;③氢氧化钠溶液浸泡,蛋白质、甲壳素膨胀,蛋白质溶解,并伴有部分蛋白的分解。碱对蛋白层与甲壳层的层间有劈开作用。碱液能实现蛋白层与甲壳层的剥离。     

利用金蝉制备甲壳素

从金蝉中提取甲壳素,对制备工艺、脱色条件、酸碱浓度及用量等进行研究。结果表明,金蝉中含有较多的蛋白质,甲壳素含量为10％～12％。     

从虾蟹壳制备甲壳素及壳聚糖的研究

本文以云南出产的蟹、虾的外壳为原料,制备出粘度高、色泽洁白的甲壳素和壳聚糖产品。同时,对制备过程中酸、碱的浓度、反应温度和时间,配料比以及氧化还原的条件等对产品质量和收率的影响进行了研究。找出了较好的生产工艺条件。     

Synthesis and FTIR spectroscopic studies on shear induced oriented liquid crystalline chitin/poly(acrylic acid) composite

Liquid crystalline chitin/poly(acrylic acid) composite, with its unique optical properties, was fabricated by the free‐radical photopolymerization of acrylic acid in an aligned mesophase. Alignment of the mesophase was achieved by unidirectional shearing. The developed composites, coated on calcium fluoride (CaF₂) substrate, were transparent, and the alignment was retained depending on the mesophase composition of the ternary dispersion (chitin microfibrils, water, acrylic acid). According to studies from polarized FTIR spectroscopy, both the degree of orientation and the molecular interactions were strongly affected by respective mesophase behavior. The average molecular chains of chitin microfibrils were oriented along the shear direction. A high dichroic ratio value of about 25, observed in composites of chitin/poly(acrylic acid) with a w/w ratio of 55:45, opens an interesting avenue to prepare a new chitin‐based optically anisotropic composite. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 90: 1932–1940, 2003