聚电解质渗透汽化膜

介绍了聚电解质渗透汽化膜的研究进展,包括聚电解质以及聚电解质复合物的定义、特点、制备、着重介绍了近年来开发的一些重要的聚电解质渗透汽化膜的制备方法及其分离性能。     

壳聚糖基聚电解质复合物在生物医学领域的应用

近年来,国内外对壳聚糖在生物医学领域的应用研究十分活跃。壳聚糖在低pH时带正电荷,在溶液中可与带负电荷的聚离子形成聚电解质复合物。壳聚糖基聚电解质复合物除了具有壳聚糖的生物相容性,还表现出良好的物理化学性质,在药物控制释放体系、蛋白质分离、生物酶以及细胞固定化等领域具有广泛应用。本文重点介绍壳聚糖与几种天然的或合成的聚阴离子形成的聚电解质复合物及其在生物医学领域的应用。     

Fluorescence study of polyelectrolyte complex formation III: Mobility of probes in microdomains

The mobility of fluorescent probe molecules in the microdomains formed by polyelectrolyte complexes (PEC) in aqueous solution was investigated by the fluorescence polarization method. The degree of fluorescence polarization (p) for the anthracene (Anth) chromophores attached to anionic polyelectrolytes increased with complexation, indicating the restricted mobility of probe molecules in the PEC microdomains. These p values depended on the properties of added polycations, which were not in parallel with the fluorescence intensities of the Anth chromophores.     

A new photoimaging system based on a trisdiazonium salt as a photocrosslinker for sulfonated polyelectrolytes

A photocrosslinker based on a trisdiazonium salt has been synthesized from 4,4′,4″-triaminotriphenylamine. Polyelectrolyte complexes can be obtained by mixing the trisdiazonium crosslinker with poly(styrenesulfonate) (PSS). The polyelectrolyte complex precipitates when PSS is added in an ionic ratio of around 1:1 to a trisdiazonium salt solution. However, the addition of an excess of PSS to the mixture leads to redissolution of the precipitate. A mixture of PSS and the photocrosslinker (27 wt.%) can be processed from solution to give thin films by spin coating. When the films are irradiated with UV light, a change in the solubility of the material is observed, which is due to the decomposition of diazonium groups and the transformation of the ionic bond into a covalent one, which in turn transforms the polyelectrolyte complex into a covalent network. The process has been characterized by UV and IR spectroscopy. Photoimaging experiments have been performed on this material and polymeric relief structures have been obtained through a photolithographic process.     

熔体静电纺丝研究进展

静电纺丝法是制备超细/纳米纤维的一种有效方法。相对于研究已经较为深入广泛的溶液电纺,熔体电纺还处于研究的初级阶段。但其原料适用性广、无毒无污染及产品转化率高等特点,使其在过滤、生物医药等领域有着广阔的应用前景。同时,熔体电纺也存在装置较复杂、纤维直径较粗等缺陷。本文介绍了目前熔体电纺的各典型装置,总结了用于熔体电纺的聚合物种类、实验工艺,比较了各种聚合物纺丝过程中的参数对纤维物化性质的影响,探讨了熔体电纺纤维的应用,并对其发展方向进行了预测和展望。     

冻胶纺丝法制备高强度高模量纤维

本文概述了冻胶纺丝技术发展简况,以聚乙烯为例,对冻胶超高拉伸制备高强度高模量纤维的原理以及制备过程和用途作了介绍。     

脱乙酰壳多糖─羧甲基纤维素聚电解质复合物的合成和药物控制释放研究

本文研究合成条件对脱乙酰壳多糖─羧甲基纤维素聚电解质复合物的组成、结构及药物控制释放性能的影响。结果表明,反应介质的ｐＨ值对生成的脱乙酰壳多糖─羧甲基纤维素聚电解质复合物的组成和结构的影响最大,在ｐＨ值５．５合成的脱乙酰壳多糖─羧甲基纤维素聚电解质复合物具有较好的药物控释性能。     

A facile route for fabricating novel polyelectrolyte complex membrane with high pervaporation performance in isopropanol dehydration

Polyelectrolyte complexes (PECs) of sodium carboxymethyl cellulose (CMCNa) and poly(diallyldimethylammonium chloride) (PDDA) were prepared in dilute hydrochloric acid (HCl) aqueous solution and obtained in its solid form. Element analysis and FT-IR showed that the composition of PECs could effectively be tuned by the concentration of HCl in parent polyelectrolyte solution. The PECs were then dissolved in 0.1 mol/L aqueous NaOH and subsequently cast onto polysulfone ultra-filtration membrane. This composite membrane, which has a unique homogeneous PECs separation layer, was subjected to pervaporation test for the first time and gave a performance of J = 3.0 kg/m² h, α = 960 for 10 wt% water–isopropanol feed at 75 °C. Meanwhile, performance of the PECs membrane displays good stability and unique dependence on feed temperature. These findings, together with its ultra-high performance, are primarily explained by the structure characteristic of PECs.     

脱乙酰壳多糖-羧甲基纤维素聚电解质复合物的合成和药物控制释放研究

本文研究合成条件对脱乙酰壳多糖－羧甲基纤维素聚电解质复合物的组成、结构及药物控制释放性能的影响。结果表明，反应介质的ｐＨ值对生成的脱乙酰壳多糖－羧甲基纤维素聚电解质复合物的组成和结构的影响最大，在ｐＨ值５．５合成的脱乙酰壳多糖－羧甲基纤维素聚电解质复合物具有较好的药物控释性能。     

聚电解质复合物溶解性研究

报道了聚电解质复合物的一种新的溶剂体系———离子表面活性剂剂的水溶液 ,研究了表面活性的用量及结构、温度、外加小分子电解质对复合物溶解性的影响 ,初步探讨了溶解机理 ,通过扫描电镜观察了复合物溶解后在溶液中的形态 .研究表明 ,当复合物与离子表面活性剂定量结合到一定程度时 ,就会使复合物发生溶解 .表面活性剂碳链长度的增加、温度的提高均会对复合物的溶解有不同程度的促进 .加入少量的无机电解质如氯化钠 ,会促进复合物的溶解 ,若氯化钠加入量过多 ,反而不利于复合物的溶解 .复合物的溶解机理被认为是表面活性剂的解离作用和疏水作用二者的协同 .     

Polyelectrolyte complex of chondroitin sulfate and peptide with lower pI value in poly(lactide-co-glycolide) microsphere for stability and controlled release

A polyelectrolyte complex between a therapeutic peptide and chargeable polymer was applied to prevent peptide denaturation in poly(lactide-co-glycolide) (PLGA) microspheres. Chondroitin sulfate A (CsA) was employed as a polymeric additive for the formation of an ionic complex with insulin (InS). The complex prepared at pH 3.0 evidenced a nano-size in the range of 100–400 nm with a mono distribution. The stability of InS in the complex in an organic/water (O/W) interface was verified via RP-HPLC. The insulin in the complex evidenced a retention time almost identical to native InS, whereas free insulin did not evidence such a retention time. On the basis of these studies, PLGA microspheres including a complex with various CsA/InS ratios were prepared via a double-emulsion method (PLGA/CsA MS). InS loading efficiency in the system is higher than that of the microspheres without CsA. The system evidenced a lower initial burst and, following the initial burst, continuous release kinetics for 30 days. Circular dichroism (CD) spectra demonstrated that the insulin in PLGA/CsA MS is more stable than the PLGA-only microspheres (PLGA/only MS) for 20 days. These results indicate that the complex system with CsA is useful for the long-term delivery of peptides with lower pI values.     

Characterization and biodegradation of chitosan-alginate polyelectrolyte complexes

Polyelectrolyte complexes (PECs) have been the focus of an expanding number of studies for their wide use. This study investigated the characteristics and biodegradation of chitosan-alginate PECs prepared by freeze-drying a precipitate from sufficient mixtures of the two polymers. The analyses of X-ray photoelectron spectroscopy (XPS), Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD) and differential scanning calorimetry (DSC) suggested that the partial protonated amine groups of chitosan reacted with the carboxylate groups of alginate and thus strong PECs were formed. After incubating in lysozyme solution, the PECs showed high ability of enzyme adsorption, and low degradation rate in spite of different degrees of deacetylation of chitosan, due to the strong interaction between chitosan and alginate and the hindrance of closely adsorbed lysozyme.     

Complexation between DNA and Peptides with Precisely Controlled Charge Density and Distribution

Using three designed peptides with precisely-controlled charge density and three types of DNAs with different length and flexibility, the effect of charge density on the formation of PEC was studied. Highly charged（KKKK）5 interacts strongly with 21 bp ds DNA to form large complex, followed by precipitation; while the medium charged（KGKG）5 only form complex with 21 bp ds DNA at proper ＋/- charge ratios; and no prominent complex between weakly charged（KGGG）5 and 21 bp ds DNA is observed at the same conditions. Similar trend is observed when the peptides form complex with 2000 bp DNA or 21 nt ssD NA. It is also found that the complex formed by adding peptide to DNA is in random coil conformation, but the complex prepared by the inverse order is in molten globule state. Re-dissolution of the complex occurs only when DNA is added to peptides with similar or shorter length.     

Controlled phase separations in solutions of soluble polyelectrolyte complex of DIVEMA (copolymer of divinyl ether and maleic anhydride)

Copolymer of divinyl ether and maleic anhydride (DIVEMA) is known to possess some anti-tumor and immune-stimulating activity and use as a drug carrier in anti-tumor drug delivery systems. Samples of DIVEMA of different degrees of polymerization were synthesized and characterized. Interaction of the hydrolyzed water-soluble DIVEMA polyanions with poly(N-ethyl-4-vinylpyridinium) cations (PEVP) has been studied. According to the potentiometry data, almost all carboxylic groups of the polyanions were able to form ion pairs with PEVP. In aqueous and water-salt solutions, formation of either soluble or insoluble polyelectrolyte complexes occurred depending on pH, ratio of the oppositely charged groups, and degree of polymerization of PEVP and/or DIVEMA. The phase separations followed general rules revealed by studying mixtures of PEVP and polycarboxylic acids. However in the case of DIVEMA, a significant broadening of the region for insoluble complexes at the expense of the region of soluble complexes was established. The data obtained demonstrate plausible advantages of the complex formation as the non-covalent modification of the polymeric carrier that endow DIVEMA with the ability for reversible soluble-insoluble transformation, in particular at physiological pH and ionic strength.     

Layer-by-layer self-assembly of polyelectrolyte complexes and their multilayer films for pervaporation dehydration of isopropanol

Two negatively charged polyelectrolyte complex colloidal nanoparticles (PEC⁻) and one positively charged nanoparticle (PEC⁺) were prepared and used as novel layer-by-layer (LbL) building blocks. These PEC nanoparticles include poly(2-methacryloyloxy ethyl trimethylammonium chloride)/sodium carboxymethyl cellulose (PDMC/CMCNa PEC⁻), poly(diallyldimethylammonium chloride)/CMCNa (PDDA/CMCNa PEC⁻) and PDDA/poly(sodium-p-styrenesulfonate) (PDDA/PSS PEC⁺). LbL multilayer films based on (PEC⁺/PEC⁻) were constructed on both quartz slides and modified polyamide (MPA) reverse osmosis support membranes. UV–vis spectroscopy, quartz crystal microbalance (QCM), field emission scanning microscopy (FESEM) and atomic force microscopy (AFM) were utilized to follow the thickness growth and morphology evolution of these multilayer films with increasing bi-layer numbers. LbL multilayer films deposited on MPA support membranes were subjected to pervaporation dehydration of 10 wt% water–isopropanol and effect of bi-layer numbers and feed temperature on pervaporation performance was studied. Generally, PEC⁺/PEC⁻ can be LbL self-assembled successfully on both substrates with a thickness growth rate ca. 200 nm/bi-layer. Moreover, PEC⁺/PEC⁻ multilayer films show high pervaporation performance with film thickness up to several micrometers. For example, performance of the multilayer films in dehydrating 10 wt% water–isopropanol at 50 °C is J = 1.18 kg/m² h, α = 1013 for (PEC⁺/PDMC-CMCNa PEC⁻)₂₄ and J = 1.36 kg/m² h, α = 938 for (PEC⁺/PDMC-CMCNa PEC⁻)₂₅, respectively.     

重氮树脂型聚电解质复合物与SDS相互作用研究

由于聚电解质与表面活性剂的相互作用具有很多特别的性质而倍受关注［１～１０］,但具有感光性的重氮树脂作为正离子聚电解质与表面活性剂相互作用尚未见报道．本文研究了重氮树脂（ＤＲ）与聚苯乙烯磺酸钠（ＰＳＳ）形成的聚电解复合物（ＤＲ－ＰＳＳ）与十二烷基硫酸钠...     

聚电解质复合物在表面活性剂水溶液中的溶解机理

聚电解质复合物 ( PEC)因其独特的物理化学性质而受到广泛关注 .对其研究主要集中在其结构及形成的影响因素 ,如聚电解质的分子量 [1,2 ] 、电荷密度、电荷强弱 [1,2 ] 及溶液离子强度 [3,4 ] ,而很少有关于聚电解质复合物溶解性的报道 [5,6 ] .一般认为组成 PEC的聚正离子 ( PC)和聚负离子 ( PA)之间 ,通过离子键形成网状交联结构而不溶于水及有机溶剂 .只有一种特殊的溶剂体系屏蔽溶剂可溶解此类复合物[7,8] .本文报道一类新的聚电解质复合物 :以二苯胺重氮树脂 DR为聚正离子 ,苯乙烯 -马来酸酐碱性水解物 ( PSMNa)为聚负离子的 P…     

Synthesis and photophysical properties of colloids fabricated by the layer-by-layer polyelectrolyte assembly onto Eu(III) complex as a core

The luminescent colloids have been synthesized through the layer-by-layer assembly of poly(sodium 4-styrenesulfonate) (PSS) and polyethyleneimine (PEI) onto the luminescent core. The latter has been obtained by the reprecipitation of complex Eu[(TTA)(3)1] (where TTA(-) and 1 are thenoyltrifluoroacetonate and 2-(5-chlorophenyl-2-hydroxy)-2-phenylethenyl-bis-(2-methoxyphenyl)phosphine oxide, respectively) from organic solvent to aqueous solution. The variation of Eu(III) complexes indicates the role of the complex core in the development of such core-shell colloids. Complex Eu[(TTA)(3)1] is most convenient precursor of Eu-doped luminescent nanocomposites. The fluorometric measurements at each step of the layer-by-layer polyelectrolyte assembly onto Eu[(TTA)(3)1] core, at various pHs and additives reveal the quenching of Eu-centered luminescence as a result of the interfacial interaction of the core and the dye. The AFM images and electrochemical behavior of PSS-(PEI-PSS)(n)-Eu[(TTA)(3)1] colloids deposited on the surface indicate the stability of the polyelectrolyte multilayer in the dried state.     

Nanocomposite-based lignocellulosic fibers 1. Thermal stability of modified fibers with clay-polyelectrolyte multilayers

The layer-by-layer (LbL) assembly process of creating highly structured thin films derived from layers of polyelectrolytes and nanoparticles was adopted in this study to modify the surface of lignocellulosic fibers. Aqueous dispersions of clay nanoplatelets were created with ultrasonication and characterized with dynamic light scattering and atomic force microscopy in which confirmed the presence of individual clay nanoplatelets. Film thickness of never-dried clay and poly(diallyldimethylammonium chloride) (PDDA) multilayers was studied with a quartz crystal microbalance with dissipation monitoring (QCM-D). Using identical LbL deposition parameters, a slurry of steam-exploded wood fibers was modified by alternate adsorption of PDDA and clay with multiple rinsing steps after each adsorption cycle. Zeta potential measurements were used to characterize the fiber surface charges after each adsorption step while SEM images revealed that the LbL film masked the cellulose microfibril structure. Using a thermogravimetric analyzer, LbL modified steam-exploded wood fibers were observed to attain increased thermal stability relative to the unmodified material tested in both air and nitrogen atmospheres. Significant char for the LbL clay coated steam-exploded wood suggests the multilayer film serves as a barrier creating an insulating layer to prevent further decomposition of the material. This nanotechnology may have a positive impact on the processing of lignocellulosic fibers in thermoplastic matrices, designing of paper-based overlays for building products, and modification of cellulosic fibers for textiles.     

Poly(vinyl alcohol)/polyelectrolyte complex blend membrane for pervaporation dehydration of isopropanol

Poly(vinyl alcohol) (PVA) was blended with soluble polyelectrolyte complex (PEC) made from poly(diallyldimethylammonium chloride) (PDDA) and sodium carboxymethyl cellulose (CMCNa). Crystallinity, thermal transition, and thermal stability of the PVA/PEC blends were characterized by using wide angle X-ray diffraction (WAXD), differential scanning calorimetry (DSC), and thermal gravity analysis (TGA), respectively. Surface morphology, cross-section and phase structure of the blend membranes were examined by field emission scanning electron microscopy (FESEM) and atomic force microscopy (AFM). Surface hydrophilicity and swelling behavior of the blend membranes were examined by water contact angle (CA) and swelling tests. Blend membranes were subjected to isopropanol dehydration, and effects of blend composition, feed composition and feed temperature on pervaporation performance are discussed in terms of phase structures of blend membranes. A performance of J = 1.35 kg/m² h, α = 1002, was obtained for blend membrane containing 50 wt% PEC in dehydrating 10 wt% water–isopropanol at 70 °C.