两亲性羧甲基壳聚糖衍生物的表面活性研究

将羧甲基壳聚糖与烷基缩水甘油醚在碱性条件下反应,合成了一系列新型的两亲性化合物(2-羟基-3-烷氧基)丙基-羧甲基壳聚糖,对其表面性质的研究结果表明,对同一衍生物,在所研究范围内,取代度越高,降低表面张力的能力及效率越高;对同一取代度的不同衍生物,疏水链越长,降低表面张力的能力越强;对链较短和取代度较大的衍生物,如(2-羟基-3-丁氧基)丙基羧甲基壳聚糖(HBP-CMCHS),在外加电解质存在时溶液的表面张力曲线出现2个转折点,表明可能有分子内胶束形成;而对链较长的衍生物,如(2-羟基-3-十二烷氧基)丙基羧甲基壳聚糖(HDP-CMCHS),则无明显的临界胶束浓度,有外加电解质时表面张力曲线也未出现2个转折点.     

羧甲基壳聚糖对亚铁离子的吸附

壳聚糖是由甲壳素经脱乙酰基后得到的一种天然高分子氨基多糖 ,它是金属离子的良好配体 ,其配合物在工业、农业、食品、环保、医药等方面的应用已有许多研究 [1～ 4 ] .脱乙酰基后的壳聚糖溶解性有很大改善 ,但仍只能溶于酸或酸性水溶液 ,限制了它的推广应用 .通过化学改性的羧甲基壳聚糖 ( CMCS)具有良好的水溶性、保湿性、乳化性 ,其分子中含有— OH、— NH2 、—COOH等基团 ,能有效络合金属离子 [5] .人体对壳聚糖 -亚铁络合物的吸收远远大于传统的 Fe SO4 药物 [6 ] ,壳聚糖及其衍生物与 Fe2 的络合物有可能用于治疗缺铁性贫血 …     

电导滴定法同时测定羧甲基壳聚糖的取代度、脱乙酰度和-COONa分布系数

<正>羧甲基壳聚糖是壳聚糖的重要水溶性衍生物之一,具有良好的保湿性、乳化性、成膜性、抗菌性、络合性和安全无毒性等优点,是一种在工业、农业、食品、环保和医药等领域有广泛应用的两性醚聚合物[1-3]。取代度(DS)和脱乙酰度(DD)是影响羧甲基壳聚糖质量和化学性质的两个重要参数,-COONa型体分布系数则是决定其水溶性的另一     

水溶性O-羟乙基壳聚糖的合成

壳聚糖[β-1→4）-2-氨基-2脱氧-D-葡萄糖]是目前发现的生物界唯一存在的碱性氨基多糖,具有无毒、可生物降解、良好的成膜性和生物相容性,近年来已在水处理、医药、食品、化妆品、农业等领域显示了其独特的应用用价值。但壳聚糖只溶于酸,在很大程度上限制了它的推广应用。通过降解     

羧甲基壳聚糖衍生物及其振动光谱的理论研究

用量子化学从头算STO 3G法研究了羧甲基壳聚糖及其衍生物的结构和稳定性，计算结果表明:1)壳聚糖单体经羧甲基化后，得到2种可能的产物，其中羧甲基在壳聚糖单体2位氨基上的取代产物较6位羟基上的取代产物稳定； 2)以羧甲基壳聚糖为母体经加成反应，得到羧甲基壳聚糖衍生物（2 羟基 3 丁氧基）丙基 羧甲基壳聚糖的2个异构体， 其中构型1更稳定.在优化构型的基础上，计算所得的构型1的振动光谱与实验结果相吻合.     

羧甲基壳聚糖与钙离子络合作用的研究

羧甲基壳聚糖(carboxymethyl chitosan,CMCS)是壳聚糖Chitosan经化学改性得到的水溶性衍生物,由于羧基的引入,络合金属离子的能力及反应速度大大提高[1-6],在医药、化工、环保等领域有着广泛的应用前景。本文研究了羧甲基壳聚糖与Ca2 络合的条件,着重探讨了Pb2 在不同条件下对络合反应的影响,以期扩大羧甲基壳聚糖的应用范围。1材料与方法1.1仪器与试剂羧甲基壳聚糖(自制),其它试剂均为国产优级纯。TAS-986G原子吸收分光光度计;SX5-12箱式电阻炉;GL-20B高速冷冻离心机;Ori-on818型pH测试计。1.2实验方法1.2.1羧甲基壳聚糖与Ca2 络合…     

羧甲基壳聚糖-PEG双缩水甘油醚凝胶微球的制备与表征

羧甲基壳聚糖是壳聚糖-NH2或-OH被羧甲基取代后的一类衍生物,具有优良的生物相容性和生物可降解性,同时具有抗菌作用。作为生物医用材料应用的潜力巨大。制备羧甲基壳聚糖生物膜或凝胶时多以戊二醛为交联剂[1],但戊二醛有一定的细胞毒性[2-3],用作医用材料的制备时有一定的局限     

N,O-羧甲基壳聚糖的合成和性质研究

采用多段升温法将壳聚糖改性,合成了取代度为1.84、平均分子量为3.08×105、等电点为7.28的N,O-羧甲基壳聚糖(CMC),分别用紫外光谱、红外光谱、荧光光谱对其结构进行了表征,并对其水溶液的Zeta电位、电导率、表面张力以及水分散体系中羧甲基壳聚糖微粒的粒径分布进行了研究.结果表明, N,O-羧甲基壳聚糖具有表面活性;介质的pH值和浓度对羧甲基壳聚糖溶液的稳定性有很大的影响.     

N－羧丁基壳聚糖的吸湿性和保湿性

透明质酸具有良好的吸湿、保湿性能 ,被认为是“理想的天然保湿因子”。但是从动物组织中提取的产品 ,工艺复杂 ,成本较高 ;而发酵法制备的产品 ,还完全达不到天然提取产品的理化性能 [1] 。甲壳素脱乙酰基后得到的壳聚糖具有一定的水分调节能力 [2 ] 。但壳聚糖有较强的分子间氢键 [3] ,只能溶于有机或无机酸的溶液中 ,而不溶于水 ,从而限制了它在日化方面的广泛应用。为此 ,近年来已制备了一系列水溶性壳聚糖衍生物 [4 ,5] ,其中与透明质酸具有相近结构的羧甲基壳聚糖的研究报道较多[5～ 7] ,但在相近分子量时仍达不到透明质酸的保湿效果 …     

低分子量壳聚糖及其水溶性衍生物对质粒DNA和mRNA的影响

研究了低分子量壳聚糖及其O-羧甲基壳聚糖和O-羟乙基壳聚糖在不同质量分数和作用时间下,对大肠杆菌质粒DNA(pBR322和pUC18)的体外结合能力。研究结果表明,原料壳聚糖对2种质粒都有较强而稳定的结合能力;其2种衍生物对质粒的作用效果受空间位阻效应和氨基基团数量的共同影响,在适当的质量分数(≥1×10-2)和相对分子质量(2000,5000,8000及以上)的条件下,对质粒DNA都具有很强的结合能力。研究表明,壳聚糖及其衍生物对DNA的结合是基于正负电荷的静电吸引作用,结合过程短暂,结合能力不受作用时间的影响。相对分子质量为3000～5000的原料壳聚糖和O-羧甲基壳聚糖均可以有效阻碍mRNA的复制,且O-羧甲基壳聚糖在同等条件下影响作用较大,推测是由于此种衍生物对氨基的质子化能力较大和体积庞大造成。大肠杆菌体内转化实验表明,壳聚糖和O-羧甲基壳聚糖不仅可以和DNA结合而使之不能转化,而且可以直接阻碍正常质粒DNA向大肠杆菌的转化过程。     

(2-羟基-3-丁氧基)丙基-羧甲基壳聚糖的合成及表面性质

(2-羟基-3-丁氧基)丙基-羧甲基壳聚糖的合成及表面性质;壳聚糖衍生物; (羟基丁氧基)丙基-羧甲基壳聚糖;表面活性;表面压     

Preparation and properties of a new type of comb-shaped, amphiphilic cellulose derivative

Comb-shaped, amphiphilic O-(2- hydroxy-3-butoxypropyl) cellulose (HBPC) was prepared by a homogeneous reaction of cellulose with butyl glycidyl ether (BGE) in a 10% (w/w) LiCl--DMAc solution. It was found that: (a) the molar substitution (MS) of water-soluble HBPC ranges from 0.4 to 1.0, and is nearly equal to its degree of substitution (DS), indicating that the HBPC derivatives obtained are comb-shaped polymers; (b) the water-soluble HBPC shows a thermally reversible sol-gel transition in aqueous solution; and (c) the derivative having a DS of 0.6 shows surface activity with critical micelle concentration (cmc) in the order of 0.8 g/l and surface tension of 31.5 dyn/cm     

Chemical surface modification of poly(p-xylylene) thin films

Electrophilic aromatic substitution reactions were studied at poly(p-xylylene) (PPX) film surface-reaction medium interfaces. The extent of the reactions (depth of penetration and degree of substitution) was determined by the interaction of the polymer with the reaction solution. Reaction with chlorosulfonic acid to produce sulfonyl chloride and sulfone functionalities occurred readily in the bulk of PPX, and yields were sensitive to time and temperature. Confinement of this reaction to the PPX surface was achieved by controlling the concentration of the acid. Functionalization of PPX with N-methylol-2-chloroacetamide in sulfuric acid to produce the chloroamidomethylated derivative occurred in high yield and was confined to the surface region of PPX. Hydrolysis of the amide to generate aminomethylated PPX was assessed by XPS and a derivatization reaction. Friedel-Crafts type chemistry (acylation and alkylation reactions) also produced functionalized surfaces, but with lower degrees of substitution than the other two reactions and was strictly surface-confined.     

The aggregation behavior between anionic carboxymethylchitosan and cetyltrimethylammonium bromide: MesoDyn simulation and experiments

The aggregation behavior between carboxymethylchitosan (CMCHS) and cetyltrimethylammonium bromide (CTAB) is investigated by MesoDyn simulation and experimental techniques, for increasing CTAB concentrations. Mixed CMCHS/CTAB bulk aggregates are formed in the solution. Simulation results give the morphologies of aggregates clearly and illustrate the two stages for the formation of aggregates: the first stage is CTAB molecules aggregating on the CMCHS chain and the second stage is the equilibrium stage. A viscosity maximum and a hydrodynamic radius minimum at a certain CTAB concentration reveal the bridging structure of the polymer chains by the micelles. Transmission electron microscopy (TEM) images give the bridging structure clearly. At higher surfactant concentrations, light scattering and TEM show the existence of larger structures, whose size increases with CTAB concentration. According to the simulation and experimental results, the process of aggregate formation and aggregation mechanism are analyzed. Initially CMCHS and CTAB form network structure due to the bridge action of CTAB micelles, while the network structure disappears gradually and is replaced by ellipsoidal CMCHS/CTAB aggregate structure with CTAB concentration increasing.     

Enhancement of Li-ion battery performance of graphite anode by sodium ion as an electrolyte additive

Electrochemical performance of a graphite electrode for lithium-ion batteries was successfully and easily improved by sodium ion dissolved in an electrolyte solution. Sodium ion was added by dissolving 0.22 mol dm⁻³ NaClO₄ into a 1 mol dm⁻³ LiClO₄ ethylene carbonate–diethyl carbonate (1:1 by volume) electrolyte solution prior to charge–discharge cycle. By sodium-ion addition, an irreversible capacity at the initial cycle was obviously reduced, and reversible discharge capacities increased with better capacity retention. From ac impedance measurements, a graphite electrode in the sodium ion added electrolyte had much smaller interface resistance compared to that obtained in sodium ion free one. Furthermore, the electrode surface morphology observed by electron microscopes after charge–discharge tests got more uniform in the sodium added electrolyte.     

Electrodeposition of metal nanostructures by galvanic displacement powered with insoluble crystals of a ferrocene derivative.

The deposition of metal nanostructures (wires and particles) on a graphite surface from an aqueous electrolyte solution was induced by galvanic displacement, via the oxidation of insoluble crystals of a ferrocene derivative (either n-butyl ferrocene or decamethyl ferrocene) present on the same substrate. Micron-to-millimetre-scale crystallites of decamethyl ferrocene were deposited on the graphite surface by evaporation from a solution of a nonpolar solvent (1,2-dichloroethane). Immersion of this modified surface into a dilute solution of a metal ion (e.g., CuII, AgI, PdII, PtII and others) caused the deposition of metal nanoparticles at step edges present on the graphite surface. The reducing equivalents required for the metal deposition process are provided by oxidation of the ferrocene derivative on the surface, as directly evidenced by elemental analysis and chronoamperometric experimental data presented here.     

Synthesis of sorption materials based on dithiooxamidate aminopropyl polysiloxane

Reaction of reamidation of rubeanic acid with aminopropyl polysiloxane was systematically studied. It was found that the given type of transformations make it possible to obtain a derivative of aminopropyl polysiloxane with surface dithiooxamide groups in a concentration of up to 0.78 mmol g^?1 at a total degree of substitution of up to 0.25. The composition and structure of the derivatives obtained were characterized by elemental analysis, IR spectroscopy, thermogravimetry, and method of low-temperature adsorption of nitrogen. The sorption of Ni(II), Pd(II), and Pt(II) in a 0.2 M solution of hydrochloric acid was evaluated for the products obtained.     

HALOMETHYLATION OF POLYSTYRENE AND SUBSEQUENT PYRIDINATION VIA A HOMOLYTIC PATHWAY

Chloromethylation of polystyrene （PS） with two different chloromethylating systems methylal/thionyl chloride and paraformaldehyde/trimethylchlorosilane was studied. Soluble chloromethylated polystyrene with a degree of substitution of 89% was obtained. The Conant-Finkelstein reaction on the chloromethylated PS afforded soluble iodomethylated polystyrene with a degree of substitution as high as 96%. The reaction conditions of Minisci were employed to radically pyridinate PS via its iodomethylated derivative. Polyelectrolytes were formed which could be converted to normal polymers by treatment with a 20% aqueous solution of NaOH.     

Study of Protein Adsorption/Adhesion Behaviors on Solid Beads Surface with Different Surface Properties

Three kinds of chitosan (CS) derivatives have been prepared via polyethyleneimine (PEI) or polyethylene glycol (PEG) together with PEI modified chitosan. FTIR, x-ray photoelectron spectroscopy (XPS), and thermal gravimetric analysis (TGA)/differential thermal analysis (DTA) proved the successful linkage, and XPS and zeta potential analysis show that these derivatives beads possess different surface nature. The PEI modified chitosan derivative is made in acid solution (A-PEI-CS) and the one added with additional PEG (PEG–CS-PEI) has showed higher swelling degree than their counterpart derivative prepared at basic condition (B-PEI-CS). Although the nitrogen content of A-PEI-CS is higher than that of B-PEI-CS, due to the better surface hydrophilicity, the B-PEI-CS beads are more capable of adsorbing bovine serum albumin (BSA) protein. Electrostatic attraction facilitates protein adsorption in a narrow acidic pH range while hydrophilicity hinders protein adhering to the beads’ surface at any pH.