壳聚糖微波辐射交联改性及其成膜

研究了在微波辐射的条件下采用戊二醛对壳聚糖进行交联,通过红外光谱等方法对交联前后成膜性能进行了研究,并与水浴加热制得的交联壳聚糖进行了对比.实验结果表明,微波交联比水浴加热迅速且均匀,分析了交联剂用量、反应时间及加热功率对膜的吸水率的影响;另外,对所成膜拉伸强度、断裂伸长率受交联反应过程各因素影响变化的规律进行了研究.     

戊二醛改性壳聚糖/ 纳米TiO2 复合膜的抗水性研究

采用戊二醛作为交联剂与壳聚糖进行交联,以提高壳聚糖/ 纳米TiO2 膜的抗水性。采用三元二次通用旋转组合设计实验方法,建立了力学性能、吸水率与戊二醛用量、交联时间、TiO2 溶胶添加量的二次回归数学模型,得出了制备戊二醛改性壳聚糖/ 纳米TiO2 膜的最佳工艺条件为交联剂用量0. 10 g/ (100 mL)乙酸溶液,交联时间4. 37 h,TiO2 溶胶添加量0. 08 mL/ (100 mL)的乙酸溶液。上述条件下得到的膜的拉伸强度为5. 69MPa,吸水率为133. 66%。与壳聚糖/ 纳米TiO2 膜相比,吸水率下降了72. 8%。     

罗非鱼鳞胶原蛋白膜抗水性和机械性能研究

以戊二醛作为交联剂对罗非鱼磷胶原蛋白交联改性。研究交联剂对罗非鱼鳞胶原蛋白膜抗水性能和机械性能的影响。通过检测改性后胶原膜的拉伸强度、断裂伸长率、抗水性、吸水率、水接触角等指标来对胶原膜进行表征。结果表明,对胶原膜机械性能影响因素依次为pH值温度戊二醛量;对胶原膜抗水性影响因素依次为戊二醛量pH值温度;当戊二醛的添加量为8%,pH值为2.9,加热温度为40℃时,胶原蛋白膜的机械、抗水综合性能最优,抗拉伸强度为31.32 MPa,断裂伸长率为65.24%,抗水性为34.85%,水接触角为120.24°。     

戊二醛交联对CCMC/PVA复合膜性能的影响

采用流延成膜工艺制备了CCMC/PVA共混复合膜,研究了戊二醛交联剂对复合膜的透光性能和力学性能的影响。结果表明:交联处理膜的致密性和机械性能显著提高;当戊二醛添加量为2%(质量分数),体系的pH为10,交联反应温度为85℃,交联时间为35 min时,复合膜的拉伸强度可达18.91 MPa,断裂伸长率为226%,透光率为75%。     

微波辐射下交联壳聚糖树脂的制备及吸附性能

以壳聚糖为原料,微波辐射加热条件下,利用反相悬浮法制备甲醛-戊二醛交联壳聚糖树脂,用于吸附废水中硫酸根离子。运用红外光谱、扫描电镜以及X射线能谱元素分析对吸附剂结构进行表征,采用静态吸附法考察制备条件对其吸附量的影响。结果表明:交联反应主要发生在壳聚糖的氨基(-NH2)和一级羟基(C6-OH)上;当微波辐射甲醛反应时间为15min,微波辐射戊二醛反应时间为30min,甲醛用量6mL以及戊二醛用量4mL,所得的交联壳聚糖树脂对硫酸根离子的吸附量达到最大。     

羟丙基纤维素/壳聚糖共混膜的制备与性能

采用溶液共混法制备了一系列不同比例的羟丙基纤维素(HPC)/壳聚糖(CS)共混膜,研究了羟丙基纤维素含量对共混膜的力学性能、吸湿性能、透光性能等的影响。结果表明,HPC/CS共混膜的断裂伸长率随着HPC含量的增加而增加,而拉伸强度则先提高后下降,且在含量为40%时共混膜的拉伸强度达到最大;共混膜在可见光区300nm~800nm的最大透光率均大于70%;随着HPC含量的增加共混膜的吸水率大大降低。     

改性酰化壳聚糖缓释肥包膜材料的制备与表征

壳聚糖与辛酰氯酰化反应,制备低取代度的酰化壳聚糖。通过元素分析计算酰化壳聚糖的取代度,并用红外光谱、核磁共振、尿素渗透测试对其结构及渗透性能进行分析和表征。以戊二醛为交联剂,制备了一系列酰化交联壳聚糖膜,用吸水倍率、接触角、X射线衍射仪、热重分析、尿素渗透等对其性能进行分析表征。结果表明,交联使酰化壳聚糖热稳定性提高;酰化交联壳聚糖缓释包膜材料结晶度下降,疏水性提高;随戊二醛含量增加,尿素累积渗透量下降,7 d内尿素累积渗透量由74.7%降低至34.2%,28 d时尿素累积渗透量为76.7%,改性酰化壳聚糖膜缓释性能良好。     

壳聚糖-聚己内酯复合膜的制备及其性能研究

为综合壳聚糖(CS)和聚己内酯(PCL)的性能,将CS和PCL在醋酸溶液中进行共混,利用流延法制备5/95,10/90,15/85,20/80 4种不同比例的壳聚糖-聚己内酯复合膜.采用元素分析、FTIR、XRD和SEM对膜的组分、结构和形貌进行了表征,证明了壳聚糖和聚己内酯在复合膜中有一定的相容性.探讨了体系中壳聚糖含量对多孔膜的力学性能和吸水率、溶胀比、孔隙率的影响,结果表明:在实验范围内随壳聚糖含量的增加,复合膜的刚度从4 188.17N/m提高到20 436.00 N/m;杨氏模量亦从30.52 MPa增加到69.69 MPa;断裂伸长率降低.吸水率可达76.39%,孔隙率亦可增加到约35%,而溶胀比几乎不变.     

氧化微晶纤维素交联壳聚糖复合膜的制备及性能

目的 制备氧化微晶纤维素交联壳聚糖复合膜,并探索交联改性对壳聚糖复合薄膜性能的影响。方法 首先采用高碘酸钠氧化法对微晶纤维素进行氧化处理,制备氧化微晶纤维素,再通过溶液共混流延法制备不同质量分数(0%、1%、3%、5%、7%、9%)的氧化微晶纤维素交联壳聚糖复合薄膜。通过对复合薄膜组分、形貌、力学性能、光学性能、热稳定性及阻隔性能的表征,考察不同含量的氧化微晶纤维素对壳聚糖薄膜各性能的影响。结果 氧化微晶纤维素表面的醛基能与壳聚糖中的氨基发生交联反应,氧化微晶纤维素的加入可以改善壳聚糖薄膜的拉伸强度和断裂伸长率,复合薄膜的拉伸强度和断裂伸长率最大分别达到了43.07 MPa和19.42%;随着氧化微晶纤维素含量的增大,复合薄膜的紫外屏蔽性能增强,水蒸气透过系数增高,但热稳定性未见明显变化。结论 采用氧化微晶纤维素交联改性壳聚糖可以有效改善壳聚糖薄膜的力学性能和紫外屏蔽性能,有助于进一步扩大其包装应用范围。     

交联壳聚糖渗透蒸发膜分离乙醇—水

对壳聚糖/聚丙烯腈复合膜分别用戊二醛、硫酸、硫酸镍溶液进行了交联改性。交联后,分离选择性(α)大为提高。对戊二醛交联膜进行了乙醇水溶液的分离性能研究,结果表明,50℃、料液中合水率小于45%时,α大于670,渗透通量为100～700g/m~2·h。     

Sorption of U(VI) from sulfate solutions with spherically granulated chitosans

Sorption of U(VI) from sulfate solutions with spherically granulated chitosans was examined. It was shown that the best sorption and kinetic characteristics are exhibited by freshly formed and cross-linked chitosan granules. The total static exchange capacity for the freshly formed granules was 0.7 mmol of U(VI) per gram of dry sorbent. The diffusion coefficients and similarity criteria describing the diffusion process parameters were calculated. It was found that, irrespective of the method by which the granules were prepared (freshly formed, cross-linked, air-dried), the dominating process is U(VI) sorption on the surface, mainly controlled by external diffusion. Physicomechanical tests of the films of the irradiated chitosan and cellophane (absorbed dose 100–250 kGy) revealed higher strength characteristics of the irradiated chitosan.     

The effects of solvent sorption on the properties of poly(ether ether ketone)

A study has been carried out on the sorption of ortho-dichlorobenzene, N,N-dimethylformamide and water by poly(ether ether ketone) (PEEK). Two types of PEEK samples have been analysed; the first in the amorphous state and the second with a high crystallinity level. The sorption and desorption curves have been determined and the effect of the solvent presence on the mechanical properties has been analysed by means of the tensile test. PEEK is affected to a different extent by the solvents studied and also by the crystallinity of the polymer. Sorption takes place only in the case of amorphous PEEK. Its effect on the mechanical properties of PEEK is explained on the basis of the two concomitant processes that are the consequence of sorption, these are: plasticization and induced crystallization.     

壳聚糖微粉对聚氨酯多孔膜结构和性能的影响

以生物医用聚氨酯为基质,添加超细壳聚糖微粉,通过湿法相转变法制备壳聚糖微粉/生物医用聚氨酯共混多孔膜。考察了壳聚糖微粉含量对共混膜结构和性能的影响,通过SEM观察共混膜结构形态的变化,采用吸水溶胀度和透湿汽量表征膜的性能。结果表明,壳聚糖含量的变化对膜的断面形态没有显著的影响,均呈现胞腔状孔结构;但随着壳聚糖含量的增加,共混膜中微孔的孔径和孔隙率呈现先增加后降低的趋势,同时膜的吸水溶胀度和透湿汽量随着壳聚糖微粉的增加而有较大幅度的提高。     

Characterization and in vitro and in vivo evaluation of cross-linked chitosan films as implant for controlled release of citalopram

The aim of the present study is to develop cross-linked chitosan (CH) films that can release drug over an extended period of time and that too in a controlled manner. A solution of different percentages of CH, is prepared in 1% lactic acid, followed by addition of citalopram (CTP) and then reacted with increasing amounts of glutaraldehyde (GL) to obtain films with different cross-linking densities. Prepared films are characterized for their physical and mechanical properties. The films are then subjected to in vitro drug release studies using pH 7·4 phosphate buffer saline (PBS) as dissolution medium and cumulative amount of drug released is calculated. Kinetic analysis of drug release is performed using Power law model and Higuchi’s model. With increase in concentration of CH, water absorption capacity and mechanical strength are increased; whereas, water vapour permeability and elasticity of the films are decreased. The effect of cross-linking agent, GL, is such that with an increase in the amount of GL, water vapour permeability, water absorption capacity and elasticity of the films are decreased; whereas, mechanical strength increased to some extent and then decreased. In vitro release studies indicate that films containing 3% CH, cross-linked with 2–3% GL and films containing 4% CH, cross-linked 1% GL are able to sustain the drug release for a prolonged time along with releasing almost complete drug in a desired period. Out of these batches, films containing 3% CH, cross-linked with 2–3% GL are having sufficient strength, water vapour permeation, water absorption capacity and elongation at break for implantation purpose. The in vitro degradation studies and histopathological studies were carried out with a sample film (batch C3 as in table 1) in rabbit model. In vitro degradation study indicates that the films maintained their integrity for desired implantation. The histopathological studies under optical microscope indicates that on implanting, there is no evidence of any inflammation, any foreign body granuloma or any necrosis or hemorrhage. Tissue configuration remains unaltered after 30 days of implantation. So, it can be suggested that cross-linked CH films of above said composition can be used as implant for long term application in depression and related disorders.     

用于吸附氟离子的EGDE交联载镧壳聚糖的制备与表征

利用戊二醛(GLA)交联并负载La3+的壳聚糖吸附净化高氟地下水时,反应不完全的戊二醛可能会溶出而产生较大的生物毒性。选用低毒的乙二醇二缩水甘油醚(EGDE)替代GLA,对壳聚糖实施交联改性,生成交联壳聚糖微球(CEB),然后在CEB表面螯合La3+,制备新型除氟剂(CEB-La)。结果表明,交联温度是影响CEB-La吸附性能的最主要因素,交联的适宜条件为EGDE与CS的-NH2物质的量比为1∶2,20℃反应4h;螯合的适宜条件为将CEB按投加量2g/L加到0.020mol/L的La3+溶液中,40℃反应3h。所得到的吸附剂具有良好的稳定性,对质量浓度20mg/L含氟水的F-去除率达96%。红外光谱分析表明,EGDE与壳聚糖的-NH2、C6-OH发生交联反应,形成的交联产物CEB中,仲羟基与La3+配位。X射线衍射分析表明,壳聚糖微球在制备过程中结晶能力下降,有利于La3+的负载和F-的吸附,除氟剂中的镧主要以La-O化物的形式存在。     

Studies on physicochemical characteristics of chitosan derivatives with dicarboxylic acids

Chitosan (N-deacetylated derivative of chitin) was solubilised in different aqueous dicarboxylic acid solutions, including oxalic acid, malonic acid, adipic acid, azelaic acid and also in monocarboxylic acetic acid. These dicarboxylic acid solutions were used with the objective that they not only act as solvents but also enhance material properties of chitosan gel films through chemical cross-linking. The properties including conformational changes of chitosan, chemical interaction, and mechanical, morphological and thermal characteristics of selected chitosan samples studied in this work. The circular dichroism study indicated that the intensity of the broad negative transition of chitosan helical structure in the wavelength region of 190–230 nm decreased with decreasing the chain length of the dicarboxylic acids. The infrared spectra revealed the formation of amide linkage between chitosan and carboxylic acids in solid state. The cross-sections of the films produced from malonic acid and acetic acid solutions of chitosan exhibited granular morphologies with different granule sizes and hill-valley-structures under atomic force microscope. The chitosan/malonic acid film showed improved water resistance and decreased tensile properties compared with the chitosan/acetic acid and chitosan/adipic acid films. These physical characteristics of chitosan/malonic acid film are attributed to the dual effects of malonic acid, which acts as a chemical cross-linker and also as a plasticizer. A strong glass transition (T _g) peak at 166 °C in differential scanning calorimetric analysis was observed, indicating the possible plasticizing effect with malonic acid.     

Preparation and characterization of chitosan/genipin/poly(N-vinyl-2-pyrrolidone) films for controlled release drugs

The study of the physicochemical and functional properties of chitosan films cross-linked with genipin and poly(N-vinyl-2-pyrrolidone) (PVP) was performed in this work. Cross-linked films were prepared by casting method from acetic acid solutions. The structure and physical properties of the films were analyzed by infrared spectroscopy (FT-IR), nuclear magnetic resonance spectroscopy (¹³C NMR), differential scanning calorimetry (DSC) and mechanical testings. Propranolol hydrochloride was used like a model drug to determine the behavior of drug release from films. The drug release capacity was measured and compared with the degree of cross-linking, mechanical properties and swelling index.     

Electrode coatings based on chitosan scaffolds

Thin films of a biopolymer chitosan (CHIT) were cast on glassy carbon electrodes, modified by grafting Lucifer Yellow VS dye (LYVS) onto chitosan chains, and cross-linked with glutaric dialdehyde (GDI). The ion-transport and ion-exchange properties of such polymeric structures (CHIT, CHIT-LYVS, CHIT-LYVS-GDI) were studied using cyclic voltammetry, rotating disk electrode, and flow injection analysis. The results showed that the chitosan matrix supported a fast ion transport as demonstrated by aqueous-like values of the apparent diffusion coefficients of Ru(NH3)6(3)+ and dopamine in the films. Anionic LYVS dye introduced a permselectivity against anions (e.g., Fe(CN)6(4)-, ascorbate) into the CHIT-LYVS films. The cross-linking of such films with GDI further increased their permselectivity as well as their stability. A unique combination of high permselectivity and fast ion transport in the CHIT-LYVS-GDI films is discussed in terms of the mixed-transport mechanism involving both pore and membrane diffusion in a highly hydrated chitosan matrix. The results indicate that the chemically modified chitosan is an attractive new coating for the development of fast, selective, and reversible sensors.