N-马来酰化壳聚糖及其配合物的合成与表征

碱性条件下将壳聚糖脱晶,利用红外光谱（FT-IR）对其结构进行了确证,并以N,N-二甲基甲酰胺和无水乙醇为介质,将脱晶壳聚糖与马来酸酐在室温条件下摩尔比按1∶1进行酰化反应18 h,合成了取代度DS=63%的N-马来酰化壳聚糖。由FT-IR测试的结果表明了马来酸酐成功接到壳聚糖分子的氨基上。将制备的N-马来酰化壳聚糖在室温下分别与氯化锌、氯化铜反应6 h,制得N-马来酰化壳聚糖与二价锌离子和二价铜离子的配合物。采用FT-IR及电子顺磁共振光谱（EPR）对配合物的结构进行表征。结果表明,N-马来酰化壳聚糖在温和条件下能与Cu(Ⅱ)、Zn(Ⅱ)形成配位化合物,N-马来酰化壳聚糖中的氨基与羧基共同参与配位。     

水溶性马来酰化壳聚糖的制备及其pH响应研究

以碳酸钠为催化剂,室温下制备了水溶性的马来酰化壳聚糖.由红外光谱分析的结果说明了马来酸酐成功接枝到壳聚糖分子上,且酰化反应后的壳聚糖的热性能较壳聚糖有了很大提高.采用MPT-2自动滴定仪和Nano-ZS粒度仪对不同pH值下的颗粒粒径和Zeta电位进行测定,发现存在2个等电点:pH=2.24和pH=5.45.     

谷氨酸/N-琥珀酰化壳聚糖水凝胶的制备和性能

以琥珀酸酐、壳聚糖为原料制备水溶性的N-琥珀酰化壳聚糖(NSC),再以谷氨酸(GA)为交联剂,在室温条件下,一定质量的GA和NSC在水溶液中通过自组装制备了GA/NSC水凝胶,研究了GA/NSC水凝胶的稳定性和溶胀性能,运用红外光谱(IR)、差示扫描量热仪(DSC)、扫描电子镜(SEM)等对其结构进行了表征,并考察了GA/NSC水凝胶的细胞毒性。结果表明,GA/NSC水凝胶为pH响应的离子交联水凝胶,具有较好的溶胀性能及生物相容性。     

在氨基酸离子液体中均相合成马来酰化壳聚糖

合成了氯化2-氨基乙酸离子液体([Gly]Cl),由FTIR、1HNMR对其结构进行了确证,并以其质量分数2%的水溶液为反应介质,制备水溶性马来酰化壳聚糖(MACH)。用XRD和FTIR对产物进行了表征,测试结果表明:壳聚糖(CS)中引入了马来酰基,并且反应主要发生在氨基上。考察了反应时间、温度和反应物摩尔比对马来酰化壳聚糖取代度(DS)的影响,得到较佳反应条件为:n(马来酸酐)/n(壳聚糖)=2.5、反应温度60℃,反应时间5h,在该条件下马来酰化壳聚糖的取代度达90%以上。离子液体[Gly]Cl具有重复使用性,反应后的离子液体未经处理重复使用3次后,马来酰化壳聚糖的取代度仍大于89%。     

壳聚糖交联聚丙烯酸/马来酸酐吸水树脂的制备

以马来酸酐(MA)、丙烯酸(AA)为原料,过硫酸铵(APS)和亚硫酸氢钠为引发剂,N-马来酰化壳聚糖(N-MACH)为交联剂,采用水溶液自由基聚合反应合成了高吸水树脂,并用正交实验法对合成条件进行了优化,得到最佳合成条件。结果表明,当单体浓度为20%,交联剂的用量为0.03 g,AA中和度为50%,m(MA)/m(AA)为5%时,可以合成具有较好吸水性的高吸水树脂,在蒸馏水中的吸水倍率为1 560.42 g/g;合成的吸水树脂具有较好的吸水速度;不同种类盐溶液浓度的变化对吸水树脂吸水率的影响较大。     

壳聚糖及丁二酸酐酰化壳聚糖双氧水降解行为的研究

在简单均相体系下．研究了壳聚糖及丁二酸酐酰化壳聚糖在双氧水中的降解特性。采用鸟氏粘度计,利用一点法测量了降解过程中壳聚糖及丁二酸酐酰化壳聚糖的分子量,讨论了该体系下壳聚糖及丁二酸酐酰化壳聚糖的降解速率．通过红外光谱分析了双氧水对低分子量壳聚糖和低分子量丁二酸酐酰化壳聚糖结构的影响。结果表明．在该体系下·壳聚糖及丁二酸酐酰化壳聚糖的降解主要发生在反应开始后的2～3h内．此后降解产物的分子量逐渐趋于20000;相同条件下,丁二酸酐酰化壳聚糖的降解程度高于壳聚糖;红外光谱表明．采用该降解体系制备的降解产物主链结构基本没有发生变化。     

N-马来酰-L-谷氨酸的制备

以马来酸酐和味精为原料,在丙酮水溶液中反应得到N-马来酰-L-谷氨酸。产物经熔点测定、红外和核磁表征,并考察了物料配比、温度、反应时间等对酰化反应的影响。     

N-马来酰化壳聚糖的合成和性能

通过酰化反应,制备一系列取代度不同的N-马来酰化壳聚糖。测定了产物的取代度、特性黏度、相对分子质量、吸湿保湿性,并用IR、NMR进行结构表征。研究发现高取代度高相对分子质量高黏度产物(M-11)的吸湿保湿性、抑菌性均优于透明质酸,有望替代昂贵的透明质酸,开辟壳聚糖新的应用范围。     

马来酸酐酰化壳聚糖/天然橡胶复合材料的制备及其性能研究

采用胶乳共混法,分别以引发剂过氧化苯甲酰(BPO)、过二硫酸钾(KPS)、偶氮二异丁腈(AIBN)、硫黄体系(VS)为引发剂,制备马来酸酐酰化壳聚糖(MCS)/天然橡胶(NR)复合材料。试验结果表明:KPS和VS引发的MCS/NR复合材料凝胶较少;VS引发的MCS/NR复合材料的物理性能比过氧化物预硫化MCS/NR复合材料大幅提高;MCS/NR复合材料的亲水性、耐热性能和抗菌性能与NR相比明显提高,有望作为制备医用NR制品的材料。     

马来松香酰化壳聚糖的微波合成、表征及其药控释放行为

在微波辐射下,以壳聚糖和松香为原料,合成了一种新型壳聚糖衍生物--马来松香酰化壳聚糖(MRCI),并通过红外(FT-IR)、X射线衍射(XRD)、扫描电镜(SEM)、差热-热重分析(DTA-TGA)和元素分析等测试手段对产物进行了结构和性能表征.运用正交试验法研究了影响合成MRCI的主要因素:溶剂用量、物料配比、反应温度和反应时间,并确立其最佳合成条件:溶剂(DMSO)用量25 mL,物料配比(壳聚糖:马来松香,摩尔比)1:4,反应温度130℃,反应时间2.5 h,获得了最高取代度的MRCI (DS=0.45).并以壳聚糖和MRCI作为药物非诺洛芬钙缓释制剂的载体,研究了其在人工肠液和人工胃液中的缓释性能.结果表明,MRCI载体在人工肠液中有良好的缓释作用.     

Influence of ultrasonic conditioning of flocculant on the aggregation process in a tank with turbine mixer

Aggregation is a very widely encountered phenomenon in nature as well as in industrial processes. It plays an important role in processing of air and water, e.g. wastewater treatment plants, power plants, mining facilities. The new, cost-effective solutions are developed. Among the others modification of the flocculants by means of ultrasounds, mixtures with surfactants or polydispersive flocculant blends can be mentioned. Flocculants used in the aggregation process are long-chain polymers that can be of negative, positive or neutral charge. The aggregation caused by usage of such flocculants is the result of three different mechanisms: bridging, charge neutralization or electrostatic patch. The influence of ultrasonic field on the efficiency of different flocculants was investigated. Suspension of chalk in water was used and the measurements were taken in the laser particle sizer. The influence of the sonication time on flow curves is also presented.     

Influence of 2-hydroxypropyltrimethyl ammonium chloride chitosan on sedimentation and volume change behavior of cohesive soil sediments

The 2-hydroxypropyltrimethyl ammonium chloride chitosan (HACC), introducing the functional quaternary ammonium group to the structure of Chitosan, has greatly broadened the application prospect. The influence on natural cohesive soil has rarely been considered. The sedimentation tests for the natural soil in HACC solutions and the HACC-treated soils in distilled water are considered to analyze the change of sedimentation behaviors in this paper. Moreover, the potential change on the surface of soil particles, the change in particle size distribution, X-ray diffraction of Ca-montmorillonite/HACC, and scanning electron microscopy images are investigated to explain the reasons for the results. Results indicate that the surface potential of soil particles achieved reversal, and the particle size had significant agglomeration. The adsorption of HACC results in the rapid sedimentation of the treated soils in water. HACC has a significant influence on setting time and final volume. HACC cannot inhibit the interlayer swelling of Ca-montmorillonite. The dehydration process can promote the aggregation effect of the treated soils. The specific effects provided an essential train of thought to solve soil problems.     

Study of phase behavior on chitosan/viscose rayon blend film

A blend of chitosan and viscose rayon was investigated. A film was made from regenerating the blend of chitosan and viscose rayon. The film was characterized by various techniques, including Fourier transform infrared spectroscopy (FTIR), wide-angle X-ray scattering (WAXS), differential scanning calorimetry (DSC), dynamic mechanical analysis (DMA), and transmission electron microscopy (TEM). The phase behavior of the blend is influenced by its composition with or without carboxymeth-ylated chitosan (CM-Cs). Characterization of the chitosan/viscose rayon (Cs/VR) blend by DSC and DMA suggests partial compatibility of chitosan with VR and lack of compatibility in the remaining cases. Results of the TEM show that the addition of CM-Cs into the blend can improve the compatibility of Cs with VR. © 1998 John Wiley & Sons, Inc. J Appl Polym Sci 67:1965–1972, 1998     

Suspension characterization and electrophoretic deposition of Yttria-stabilized Zirconia nanoparticles on an iron-nickel based superalloy

Yttria-Stabilized Zirconia (YSZ) is the most common material for thermal barrier coatings. Suspensions of 3 mol% YSZ nanoparticles in acetone medium have been prepared in presence of different amounts of iodine as dispersant. Size distribution of particles in the suspensions and zeta potential were measured as a function of dispersant concentration. Adding 1.2 g/l iodine was found to be effective for the dispersion of YSZ nanoparticles in acetone. The stability of YSZ suspension in acetone increased with iodine content increasing until reached 1.2 g/l. Mean diameter of particles and zeta potential of the YSZ suspension in acetone were 912 nm and 2.4 mV respectively, and with addition of 1.2 g/l iodine shifted to 111.6 nm and 50.2 mV respectively. Electrophoretic deposition (EPD) process has been carried out from this suspension at different applied voltages and deposition times. A uniform green coating was obtained at voltage of 6 V and deposition time of 2 min the thickness of the green coating is measured about 25 µm.     

Studies on dynamic behavior of water in crosslinked chitosan hydrogel

The dynamic behavior of water in crosslinked chitosan (cr-CS) was studied at the molecular level by proton nuclear magnetic resonance (¹H-NMR) spectroscopy and positron annihilation lifetime spectroscopy (PALS). Proton line width was used as a direct parameter of local mobility during swelling. The dynamic behavior of water in hydrogel can be described by the two following processes: physical movement along free volume cavities in network and binding with hydrophilic groups of hydrogel. The formation of bound water and the effect of water on polymer network were correlated with the relaxation of hydrogel network. © 1998 John Wiley & Sons, Inc. J Appl Polym Sci 67:983–988, 1998     

Metachromatic behavior: Influence of the molecular weights of chitosan in thionine-sodium dodecyl sulfate system

Chitosans having three molecular weights (4.0 × 10⁴, 8.0 × 10⁴, and 16.0 × 10⁴ Da) were isolated by an ultrasonic degradation of chitin obtained from crab shell wastes and used to determine a metachromic behavior from the effect of aggregation characteristics. The metachromatic behaviors of thionine (Th)-sodium dodecyl sulfate (SDS), Th-SDS-chitosan system were investigated by the absorption and fluorescence spectroscopy.For SDS/Th < 40, the order of decrease of fluorescence intensity in Th-SDS-chitosan system was found to be 40k > 80k > 160k of molecular weight of chitosan. In spite of adding small amount of chitosan to Th-SDS system, a reversal of metachromatic behavior in the Th-SDS-chitosan system occurs. From the measurement of the solvent effect by adding ethanol to Th-SDS-chitosan system, the order of increase of the disaggregation was determined to be 40k < 80k < 160k of molecular weights of chitosan.     

Part V: Dynamic evolution of the multivariate particle size distribution undergoing combined particle growth and aggregation

The present paper presents a study on the application of the Galerkin finite element method (FEM) for the solution of the dynamic multivariate population balance equation (PBE) in batch particulate systems undergoing aggregation as well as combined aggregation and growth. The performance of the Galerkin FEM in terms of accuracy and stability was assessed by a direct comparison of the calculated particle size distributions and/or their corresponding moments to available analytical solutions as well as by comparison to univariate numerical solutions. Numerical simulations were carried out for a variety of particle aggregation and growth mechanisms including constant, Brownian, and modified Brownian aggregation as well as constant and linear growth rate functions and for a wide range of values for the aggregation and growth rate coefficients. The simulation results revealed that the proposed Galerkin FEM produces very accurate numerical solutions but at significant computational cost.     

纳米四方多晶氧化锆粉体的表面特性与分散性

采用环保型强碱共沉淀法制备出了粒度为5 0nm的四方多晶氧化锆粉体。对由该粉体所制的悬浮体在不同条件下的 ζ电位测试表明 ,氧化锆微粒的等电点为 8.1 ;对分散剂在氧化锆微粒表面的吸附和分散作用进行了考察 ,聚电解质分散剂聚丙烯酸铵 (NH4PAA ,粘均分子量为 5 0 0 0～ 80 0 0 )使氧化锆微粒的等电点降低 ;对聚丙烯酸铵在纳米四方多晶氧化锆粉体上的等温吸附进行的研究发现 ,由于聚电解质分散剂的作用 ,悬浮体中纳米氧化锆粉体微粒表面的电动特性发生了显著变化 ,悬浮体的稳定性提高