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不同pH条件下木质素磺酸钠的静电逐层自组装研究 总被引:1,自引:0,他引:1
以来源于造纸废液中的木质素磺酸钠(SL)为研究对象,利用静电逐层自组装技术,与聚二烯丙基二甲基氯化铵(PDAC)交替吸附,制备木质素磺酸钠的自组装多层吸附膜.研究了不同pH值条件下木质素磺酸钠在固体表面的静电吸附规律.木质素磺酸钠的自组装过程用紫外-可见光吸收光谱来监控,而自组装膜的表面形貌用原子力显微镜来观察.研究表明,SL与PDAC多层吸附膜的紫外-可见光吸收光谱强度随层数增加而线性增长,说明SL/PDAC多层吸附膜的厚度增长是以逐层自组装的方式进行的.木质素磺酸钠浸渍溶液的pH值对多层吸附膜的厚度和表面形貌产生重要的影响.在所研究的pH范围内,pH值越低,越有利于生成吸光度高的自组装膜,而得到的自组装膜的表面粗糙度越大。 相似文献
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Yin M Gu B Zhao Q Qian J Zhang A An Q He S 《Analytical and bioanalytical chemistry》2011,399(10):3623-3631
A new fiber-optic pH sensor is demonstrated by coating negatively charged polyelectrolyte complex (PEC−) nanoparticles, made of sodium carboxymethyl cellulose and poly(diallyldimethylammonium chloride) (PDDA), and positively
charged PDDA on the surface of a thin-core fiber modal interferometer (TCFMI) with a layer-by-layer (LbL) electrostatic self-assembly
method. The fabricated TCFMI pH sensor has different transmission dip wavelengths under different pH values and shows high
sensitivities of 0.6 nm/pH unit and −0.85 nm/pH unit for acidic and alkaline solutions, respectively, and short response time
of 30–50 s. The LbL electrostatic self-assembly process of a PEC−/PDDA multilayer is traced by quartz crystal microbalance and shows a fast thickness growth. Atomic force microscopy shows
the root mean square (RMS) surface roughness of electrostatic self-assembly nanocoating of polyelectrolyte complex/polyelectrolyte
is much higher than that of polyelectrolyte/polyelectrolyte due to the larger size of PEC− colloidal nanoparticles. The enhanced RMS surface roughness and thickness of the nanocoating can shorten the response time
and raise the sensitivity of the TCFMI pH sensor, respectively. In addition, the TCFMI pH sensor has highly reversible performance
and good durability. 相似文献
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Lin XU En Bo WANG* Zhuang LI Hong Yu ZHANG Chao QIN Department of Chemistry Northeast Normal University Changchun Changchun Institute of Applied Chemistry Academia Sinica Changchun 《中国化学快报》2001,(12)
In recent years, there has been considerable interest in the fabrication of self-assembled ultrathin multilayer films, because of their availability to form nanostructured materials with tailored architecture and properties1. The layer-by-layer (LBL) self-assembly, initially developed for pairs of oppositely charged polyelectrolytes2, is an unusually simple and versatile technique to built up of ultrathin multilayer films. A special feature of the multilayer films is that the composition, t… 相似文献
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将正电荷的壳聚糖与负电荷的磷钨酸溶液通过静电作用交替沉积在基底上组装复合多层膜。使用紫外可见光谱(UV-Vis)、红外光谱(FTIR)、X-射线光电子能谱(XPS)、原子力显微镜(AFM)和循环伏安法(CV)等手段对复合膜进行了表征。UV-Vis结果显示多层膜在特征吸收峰处的吸光度数值随膜双层数增加逐渐增大,呈良好的线性关系,表明多层膜是均匀组装的;XPS和FTIR结果证实了壳聚糖和磷钨酸被组装到膜上,AFM图形显示膜表面有一定的粗糙度,CV结果说明多层膜保留了磷钨酸的电化学性质。 相似文献
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New characterization of layer-by-layer self-assembly deposition of polyelectrolytes on cotton fabric 总被引:1,自引:0,他引:1
Layer-by-layer self-assembly deposition of polyelectrolytes on textile materials might provide a new approach to endue different
functions to textiles. Two simple characterization methods for electrostatic self-assembly deposition of two typical polyelectrolytes,
poly(sodium 4-styrenesulfonate) (PSS) and poly(diallyldimethylammonium chloride) (PDDA) on cotton fabrics were investigated
in this paper. Dyeing of the PSS/PDDA assembled cotton fabrics with anionic Direct Red 80 and cationic Methylene Blue shows
regular and observable “odd–even” oscillations in terms of color depth (K/S value), which could be utilized for the assessment of the variation of surface electric property of the cotton substrate
due to the alternate fabrication of PSS and PDDA on it. A linear increase in UV absorbance at 226 and 261 nm of treated cotton
fabrics further revealed that the growth of these layer-by-layer multilayers could be recorded by monitoring UV spectra of
assembled cotton specimens. ATR FT-IR spectra did not show any identifiable differences between cotton substrates with and
without deposition of PSS/PDDA multilayers. 相似文献
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Thin films of alternating DNA and rare earth ion Eu3+ layers from dilute aqueous solutions were fabricated onto quartz substrates and silicon wafers through the layer-by-layer (LbL) self-assembly technique. UV-visible spectroscopy shows that a uniform layer of DNA can be fully adsorbed onto each alternate Eu3+ layer. Microscopic FTIR spectra show Eu3+ interacts with both the phosphate groups and nitrogenous bases of DNA, and the formation of [DNA/Eu]n films induces a change of the conformation of the DNA secondary structure to a certain extent. Various parameters affecting the DNA or Eu3+ loading into the composite film were investigated with emphasis on the effect of the pH and ionic strength of the DNA solution used for the film preparation. Atomic force microscopy was utilized to observe the morphologies of the DNA in the films obtained at two different pH values. Small molecules, such as alpha-tenoyltrifluoroacetone (TTA), Hoechst 33258 (Hoe), and ethidium bromide (EB), are all observed to interact with Eu3+ or DNA in the [DNA/Eu]n films. The [DNA/Eu]n films incorporated with these molecules show different fluorescent characteristics, and the fluorescence intensity of the films versus the bilayer number has a good linear relationship, confirming the potential for creating a different luminescence ability of the multilayer by controlling the number of DNA/Eu bilayers. 相似文献
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Panchagnula V Kumar CV Rusling JF 《Journal of the American Chemical Society》2002,124(42):12515-12521
Cross-linking of myoglobin (Mb) promoted by 1-[3-(dimethylamino)propyl]-3-ethylcarbodiimide within films of polystyrene sulfonate after layer-by-layer self-assembly provided remarkable stabilization. Cross-linking greatly improved adhesion of the films to fused silica slides and allowed extensive optical studies over a wide pH range. Circular dichroism and visible absorbance spectra showed that Mb retained its native conformation when films were placed in solutions of pH as low as 2 and up to pH 11. Linear dichroism revealed an average orientation of the Mb iron heme cofactors of 58 degrees to the film normal. High concentrations of urea did denature the protein in the films, however. At pH 1, Mb in solution is fully unfolded but retained considerable alpha-helical content in the cross-linked films. Both the polyion film environment and cross-linking seem to play roles in stabilizing protein secondary structure and function at low pH. Cross-linked myoglobin-polyion films on pyrolytic graphite electrodes were used in strongly acidic solutions for the electrochemical catalytic reduction of trichloracetic acid, hydrogen peroxide, and oxygen. The pH-dependent catalytic reduction of trichloracetic acid was faster in 0.1 M HCl than in the medium pH range. 相似文献
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Yufei Ai Shuang Guo Qi Zhang Jing Qiao Xuanyue Gao Jun Nie Dongzhi Yang 《Frontiers of Chemistry in China》2011,6(1):48-53
Chitosan and sodium alginate have the opposite charges; they can become a gelatin by the electrostatic attraction, High-voltage
electrostatic droplet generator method was used to prepare chitosan-sodium alginate microcapsule. Multi-layer chitosan-sodium
alginate microcapsule was prepared through layer-by-layer self-assembly, and the morphology was investigated. In addition,
the release property of ofloxacin in microcapsules was studied by UV-Vis microscopy under different conditions such as pH
value, layer number, etc. The results showed that the prepared microcapsules have a smooth surface with average particle size
about 100 μm. The result of controlled release indicated that the prepared microcapsules are pH-independent, and the rate
of release decreased when the layer number increases. 相似文献
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Foam and wetting films from PEO-PPO-PEO triblock copolymers Synperonic P85 and F108 are studied under the identical conditions,
using microinterference method. The range of background electrolyte concentration, where DLVO (electrostatic and van der Waals)
forces and non-DLVO (steric) forces act in the films, is determined. From the dependence of the film thickness on pH, it is
unambiguously shown that electrostatic interactions (i.e., the potential and surface charge) in the foam and wetting films
caused by the presence of nonionic polymer surfactants arise due to the preferential adsorption of OH− ions at the solution-air interface. The films obtained below the critical pH values are sterically stabilized; i.e., a decrease
in pH induces a transition from electrostatic to steric stabilization. Three-layer models are designed for both types of films
that allow to calculate electrostatic disjoining pressure Πel. The values of ϕ0 potential of the foam film are used to calculate Πel in wetting films. A relation between the isoelectric state of foam and wetting films and their stability is found to exist
in the range of pH corresponding to electrostatic stabilization. Metastable films, film rupture, or the transition to sterically
stabilized films were also found.
The text was submitted by the authors in English. 相似文献
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Yang Y Nogami M Shi J Chen H Ma G Tang S 《The journal of physical chemistry. B》2005,109(11):4865-4871
The composite nanoparticles of Au-core capped by CdS shells of different thickness were prepared and assembled into densely packed 3-dimensional films by the layer-by-layer self-assembly (LBL) technique. These films exhibited the 3-dimensional structure of densely packed Au@CdS composite nanoparticles and the shell thickness was tunable by changing the concentration of Cd2+-thiourea complexes. These multilayer films exhibited enhanced third-order optical nonlinear responses and ultrafast response times (several picoseconds). The third-order nonlinear optical susceptibility of the film with the CdS shell thickness of 4.4 nm was estimated to be 1.48 x 10(-9) esu and the value decreases with the increase of the CdS shell thickness. The enhancement of the optical nonlinearity was explained based on the calculation according to the electrostatic approximation by the solution of Laplace's equation under the boundary conditions appropriate to the model of core-shell nanoparticles, and mainly attributed to localized electric field effects in the CdS shell region. Additionally, the nonlinearity was optimized by determination of the values of the dielectric constant and thickness of the different shell. 相似文献
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用偶氮聚电解质上的偶氮苯基团作为“探针” ,研究了侧链偶氮聚电解质聚 {丙烯酸 2 [4 (4′ 乙氧基苯基偶氮 )苯氧基 ]乙酯 co 丙烯酸 }(PEAPE)在水中的H 聚集及其对光响应性的影响 .研究发现 ,与在DMF溶液的紫外吸收光谱相比 ,偶氮聚电解质在水中的紫外吸收λmax 发生明显蓝移 ,表明在水溶液中偶氮生色团形成了H 聚集体 .溶解在DMF H2 O混合溶剂中的上述偶氮聚电解质也存在部分H 聚集 ,H 聚集程度与水和DMF的比例有关 .H 聚集体的形成使光异构化速率明显减慢 ,异构化效率显著降低 .同时 ,其光异构化动力学不符合一级指数衰减规律 ,说明该过程同时包含‘孤立的’偶氮生色团的光异构化反应和H 聚集体的光致解聚集 相似文献
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细胞支架作为组织工程的组成部分为细胞生长提供了最佳微环境 ,并对细胞生长与功能进行控制 .由于细胞对支架表面的生物识别是细胞附着、生长和增殖的基本前提 ,所以对材料表面的功能化是一个重要的课题 [1,2 ] . Shoichet等 [3 ] 通过化学反应或等离子体处理的方法 ,将蛋白质引入到材料表面而使其功能化 .基片在两种带有相反电荷的聚电解质溶液中交替吸附 ,其表面形成致密有序的超薄自组装膜 ,这种层 -层自组装技术不仅制备方法简单 ,无需特殊的设备 ,而且对膜组成和厚度能随意调控 ,以水为介质 ,对环境友好 [4~ 6] ,无疑是一项重要的表… 相似文献
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Poly(aniline) (PANi) and poly(γ-glutamic acid) (γ-PGA) have been synthesized by enzymatic catalysis and natural bacterial reactions, respectively. Layer-by-layer films have been prepared on glass or quartz slides by alternative immersions of the substrate in dilute solutions of γ-PGA and PANi, with several rinsing in between each deposition. UV-vis spectroscopy has been used to follow the evolution of the self-assembly process as well as to characterize the oxidative states of PANi. The linear dependence of the absorbance vs. the number of layers indicates a constant increase of thickness layer-by-layer. The morphology of the multilayer films, analyzed by atomic force microscopy, is granular type. Enzymatically synthesized PANi nanofilms present good electrical conductivity while γ-PGA acts as an insulating material. These differences in electrical properties and the possibility to obtain alternated multilayered films permit the construction of entirely “biological” nanocapacitors. 相似文献
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层层自组装原位聚合聚苯胺复合膜成膜机理研究 总被引:2,自引:0,他引:2
从苯胺单体出发, 通过原位聚合、现场掺杂以及基于静电力的层层自组装制备了聚苯胺复合膜. 通过苯胺活性溶液的温度及颜色变化跟踪聚合反应进程, 同时考察不同聚合反应阶段所得聚苯胺复合膜的紫外-可见吸收, 并进一步探讨聚苯胺复合膜的成膜机理. 研究表明, 成膜机制是由聚合反应初始阶段的苯胺阳离子或苯胺阳离子自由基通过静电作用快速吸附到负电性的基片表面, 形成均匀的聚合中心, 链增长生成聚苯胺; 该聚苯胺在酸性条件下经现场掺杂显电正性, 可吸附电负性的聚苯乙烯磺酸钠(PSS), 以此循环层层组装得到多层聚苯胺复合膜. 相似文献
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V. A. Kozlovskaya E. P. Kharlampieva I. Erel-Unal S. A. Sukhishvili 《Polymer Science Series A》2009,51(6):719-729
Poly(carboxylic acid) hydrogel films and hollow capsules undergo reversible size changes in response to variations in pH and/or
ionic strength. The films and capsules were obtained from hydrogenbonded poly-N-vinylpyrrolidone/poly(carboxylic acid) layer-by-layer
films by chemical crosslinking of the polyacid, followed by pH-induced removal of poly-N-vinylpyrrolidone. Surface-attached hydrogel films present attractive matrices for reversible pH-stimulated loading and/or
controlled release of large amounts of synthetic or natural macromolecules including proteins. By varying acidity of poly(carboxylic
acids), the hydrogel swelling and the corresponding values of pH for encapsulation/release of functional molecules could be
tuned in a wide range from pH 5 to 10. In addition, the capsules are capable of entrapping macromolecules by “locking” the
capsule wall with an electrostatically associating polycation, followed by the release of the encapsulated macromolecules
at high salt concentrations.
The text was submitted by the authors in English. 相似文献
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Novel azobenzene polyelectrolytes have been used to fabricate biocompatible self-assembled multilayer (SAMU) thin films of variable absorbance, thickness, organization, and morphology. The prepared SAMU films are useful for directed cell growth, and this application relies directly on control of contact and surface energy, and requires the ability to tune the surface characteristics which are critical to their development. The azo polyelectrolytes employed here were similar in their degree of polymerization and repeat unit composition of acrylic acid monomer and azo monomers, and only differ from each other due to the presence of different substituted head R-groups present on the p-position of the aromatic ring of the azo chromophores. Possession of characteristics of both the self-assembly due to acrylic acid groups, and photoswitchability of the azo monomer enable the azobenzene functionalized polyelectrolytes to exhibit novel photo-reversible applications. The azo polyelectrolytes with the substituted R-group pairs of shorter-ionized hydrophilic COOH and SO3H, shorter-non-ionized hydrophobic H and OC2H5, and larger-nonionized hydrophobic octyl C8H17 and C8F17 were used as polyanions and counter charge PDAC used as polycation to fabricate the layer-by-layer SAMU films onto glass and silicon substrates. The fabricated SAMU films were also characterized by various techniques. The UV absorption maxima, λmax p of the SAMU films move to lower wavelength relative to solution to exhibit a blue shift for the hydrophobic R-groups, while this behaviour was not observed for the hydrophilic R-groups. Similarly, the thickness, organization, morphology and other properties of the thin films were found to be dependent on the type of substituted R-groups of the azo polyelectrolytes due to the inter-related factors of ionization, hydrophobicity/hydrophilicity, solubility, and aggregation of azo PEL in the dipping solutions used for fabrication of the SAMU films. Understanding and controlling the adsorption characteristics of azo multilayer thin–film of switchable functionalities are vital to explore their potential for the development and application of new devices in diverse areas of biosensor, drug delivery systems, on-chip microscale chemical process and microfluidics systems. 相似文献
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在非水介质中制备聚电解质静电吸附自组装膜 总被引:1,自引:0,他引:1
静电吸附自组装是近年来得到广泛研究和应用的一种制备超薄膜的方法,具有操作简单,膜厚可控等很多优点,已经被广泛应用于制备各种功能薄膜材料[1~4].通常情况下,聚电解质的静电吸附自组装都是在水中进行的.一方面,聚电解质在水中可以很容易的实现电离;另一方面,以水做介质可以避免有机溶剂的污染,尤其对模仿各种生物环境非常有利.所以自1991年Decher首先报道该方法以来,绝大多数的聚电解质静电吸附自组装是以水为介质.但是,以水做介质也常常会遇到一些困难,尤其对于疏水性(包括非水溶性)聚电解质来说.在当前研究的许多热点领域中如导电、发… 相似文献