Polyaniline/Maleic Acid Copolymers Composites: Synthesis and Characterization

Summary: Polyaniline/maleic acid copolymers composites were synthesized by chemical in situ polymerization of aniline using ammonium peroxidisulfate as oxidant, in the presence of water soluble copolymers containing carboxylic groups. Fine dispersions of composite materials, soluble in N,N-dimethylformamide or dimethyl sulfoxide were obtained which can be processed as thin films and membranes for application as proton-conductive materials for electrolyte membranes of fuel cells. The composites were characterized by FTIR spectroscopy and thermal methods.     

与铬鞣有关的胶原化学研究进展

本文在回顾与制革有关的生皮胶原结构的基础上, 概述了铬鞣过程胶原与铬(?) 之间的作用, 并对近年来利用胶原计算机模型探讨鞣制反应和以提高铬鞣有效性为目的的胶原修饰化学的研究状况及其发展前景作简要论述。     

Supramolecular Systems from Natural Polymers and Maleic Polyelectrolytes

Summary: The formation of polyelectrolyte complexes by interaction between chitosan and maleic acid copolymers as strong/weak dibasic polyanions was investigated. The interaction between the sodium salt of maleic acid copolymers with styrene or vinyl acetate and the chitosan hydrochloride in aqueous solution was followed by potentiometric, conductometric and turbidimetric titration. The effect of the added low molecular salt on the complex formation was also investigated. The precipitated complexes were analyzed by FTIR spectroscopy and TG analysis. Preliminary layer-by-layer deposition experiments were performed to obtain thin films.     

The Interaction between Collagen and an Aluminum Tanning Agent

The interaction between collagen and organometallic aluminum complexes was studied. From the analysis of the IR and UV spectra, the viscosity of collagen, and the treated collagen, a possible interaction model of the collagen with the aluminum tanning agent has been found. It indicates that such an aluminum tanning agent could be used as a cleaner tanning agent in leather tanning.

Viscosity curves of the untreated collagen solution (a) and the collagen solution treated with aluminum tanning agent (b).     

Synthesis of Citric Acrylate Oligomer and Its In-Situ Reaction with Chrome Tanned Collagen (Hide Powder)

Summary: The purpose of this study was to formulate the new combined system of acrylic and citric acids, which was prepared by free radical polymerization and esterification reaction at the same time to form citric-acrylate CAC oligomer. The presumable chemical structure of this oligomer and the reaction mechanism were investigated by different spectroscopic tools (¹H,¹³C-NMR and ATR-IR), GPC and TGA/DTA. The effect as masking agent of the eco-friendly oligomer (CAC) in the chrome tanning of the collagen and the pickling of the hide was approached by the study of the hydrothermal and mechanical properties of in-situ treated/grafted chrome tanned collagen (hide powder) and pickled hide, respectively. The use of citric acrylate CAC oligomer instead of the traditional strong acids resulted in significant improvement in chrome exhaustion and physical properties of the leather.     

Complexes of lysozyme with sodium (sulfamate‐carboxylate)isoprene/ethylene oxide double hydrophilic block copolymers

Complexes between sodium (sulfamate‐carboxylate)isoprene/ethylene oxide double hydrophilic block copolymers and lysozyme, a globular protein, were formed in aqueous solutions, at pH 7, because of electrostatic interactions between the anionic groups of the polyelectrolyte block of the copolymers and the cationic groups of lysozyme. The structure of the complexes was investigated as a function of the anionic/cationic charge ratio of the two components in solution and ionic strength by static, dynamic, and electrophoretic light scattering, atomic force microscopy, and fluorescence spectroscopy. The mass and size of the micellar‐like complexes depend on the mixing ratio and the molecular characteristics (molecular weight, composition, and architecture) of the copolymer used. Complexation persists at 0.15M NaCl, the value for physiological saline, as a result of additional hydrophobic interactions between the copolymers and the enzyme. Fluorescence spectroscopy measurements indicate that the secondary structure of lysozyme does not change substantially after complex formation. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 509–520, 2007     

Covalent Immobilization of Subtilisin A onto Thin Films of Maleic Anhydride Copolymers

Enzymes cleaving the biopolymer adhesives of fouling organisms are attracting attention for the prevention of biofouling. We report a versatile and robust method to confine the serine protease Subtilisin A (or Subtilisin Carlsberg) to surfaces to be protected against biofouling. The approach consists of the covalent immobilization of the protease onto maleic anhydride copolymer thin film coatings. High‐swelling poly(ethylene‐alt‐maleic anhydride) (PEMA) copolymer layers permitted significantly higher enzyme loadings and activities than compact poly(octadecene‐alt‐maleic anhydride) (POMA) films. Substantial fractions of the immobilized, active enzyme layers were found to be conserved upon storage in deionized water for several hours. Ongoing studies explore the potentialities of the developed bioactive coatings to reduce the adhesion of various fouling organisms.

     

Bacterial Reaction Centers Purified with Styrene Maleic Acid Copolymer Retain Native Membrane Functional Properties and Display Enhanced Stability

Integral membrane proteins often present daunting challenges for biophysical characterization, a fundamental issue being how to select a surfactant that will optimally preserve the individual structure and functional properties of a given membrane protein. Bacterial reaction centers offer a rare opportunity to compare the properties of an integral membrane protein in different artificial lipid/surfactant environments with those in the native bilayer. Here, we demonstrate that reaction centers purified using a styrene maleic acid copolymer remain associated with a complement of native lipids and do not display the modified functional properties that typically result from detergent solubilization. Direct comparisons show that reaction centers are more stable in this copolymer/lipid environment than in a detergent micelle or even in the native membrane, suggesting a promising new route to exploitation of such photovoltaic integral membrane proteins in device applications.     

高效液相色谱法测定淀粉及淀粉制品中的顺丁烯二酸与顺丁烯二酸酐总含量

建立了基于高效液相色谱(HPLC)测定淀粉及其制品中顺丁烯二酸和顺丁烯二酸酐总含量的方法。通过优化得到最佳样品前处理条件为乙醇体积分数5%,超声时间10 min。色谱分离检测的最佳分析条件为:流动相:甲醇-1‰磷酸(2∶98),色谱柱:Plastisil ODS C18(250 mm×4.6 mm,5μm),检测波长214 nm,流速1.0 mL/min,柱温30℃。该方法对顺丁烯二酸的定量下限为5.0 mg/kg,线性范围为0.25～100 mg/L,相关系数为0.999 7,平均加标回收率为88%～89%,相对标准偏差(n=5)小于2%,能够满足实际检测需要。     

Isomerization of Maleic Acid to Fumaric Acid Catalyzed by Bromate Ion and Bromine

In the presence of a relatively small amount of bromate, maleic acid in aqueous sulfuric acid isomerizes catalytically to fumaric acid in the dark at room temperature. The concomitant presence of a suitable amount of bromine in CCI, phase raises the rate and yield significantly. The yield and rate of isomerization depend on the relative amounts of maleic acid, bromate, bromine, and sulfuric acid. For a favorable condition, nearly 90% yield can be obtained. Raising the temperature accelerates the production of fumaric acid while decreases the final yield. The isomerization reaction competes favorably with the redox reaction at room temperature while the latter dominates at high temperature. For the heterogeneous case, the agitation of the reaction mixture delays the isomerization. The presence of cumene or benzene inhibits the isomerization. Hypobromous acid is proposed to play a major role in catalyzing the isomerization. A mechanism is proposed to rationalize the experimental results.     

离子色谱法测定乙醛酸中的顺丁烯二酸和乙二酸

采用抑制电导离子色谱法测定高浓度乙醛酸基体中痕量的顺丁烯二酸和乙二酸。将乙醛酸样品稀释至1 000倍体积后,采用高浓度的淋洗液,以高容量色谱柱对样品进行分析。实验结果表明,顺丁烯二酸和乙二酸最低检出限分别为12.7,19.6μg/L,重现性(n=5)分别为1.13%,1.11%,回收率分别为97.9%,94.7%。该方法具有较高的灵敏度,适用于乙醛酸的例行检测。     

Electrospun Mats from Styrene/Maleic Anhydride Copolymers: Modification with Amines and Assessment of Antimicrobial Activity

New antimicrobial microfibrous electrospun mats from styrene/maleic anhydride copolymers were prepared. Two approaches were applied: (i) grafting of poly(propylene glycol) monoamine (Jeffamine® M‐600) on the mats followed by formation of complex with iodine; (ii) modification of the mats with amines of 8‐hydroxyquinoline or biguanide type with antimicrobial activity. Microbiological screening against S. aureus, E. coli and C. albicans revealed that both the formation of complex with iodine and the covalent attachment of 5‐amino‐8‐hydroxyquinoline or of chlorhexidine impart high antimicrobial activity to the mats. In addition, S. aureus bacteria did not adhere to modified mats.

     

离子液体固定相离子色谱法测定淀粉中的顺反式丁烯二酸

采用新型聚合离子液体嫁接硅胶多模式色谱固定相(Sil-pC11C1Im柱,4.6 mm×150 mm),建立了淀粉中顺反式丁烯二酸的新型离子色谱测定方法。实验通过考察流动相的pH值和无机盐浓度对分离检测顺、反丁烯二酸的影响,得到优化的色谱条件:流动相为甲醇-10 mmol/L磷酸二氢钠(体积比为5∶95,pH7.0),流速为1.0 mL/min,检测波长为215 nm,进样量为15μL。在优化条件下,顺反式丁烯二酸的线性范围为0.1~2.0 mg/L,回收率为93.0%~99.6%,相对标准偏差(RSD,n=5)为1.1%~7.6%,检出限(S/N=3)为0.02 mg/L,定量下限(S/N=10)为0.66 mg/kg。该方法样品前处理简单、快速,定性定量检测效果良好。     

Polymer‐Peptide Block Copolymers – An Overview and Assessment of Synthesis Methods

Incorporating peptide blocks into block copolymers opens up new realms of bioactive or smart materials. Because there are such a variety of peptides, polymers, and hybrid architectures that can be imagined, there are many different routes available for the synthesis of these chimera molecules. This review summarizes the contemporary strategies in combining synthesis techniques to create well‐defined peptide‐polymer hybrids that retain the vital aspects of each disparate block. Living polymerization can be united with the molecular‐level control afforded by peptide blocks to yield block copolymers that not only have precisely defined primary structures, but that also interact with other (bio)molecules in a well defined manner.

     

马来酸在多孔铅锌电极上电还原特性

在甲磺酸镀液中电沉积Pb-Zn镀层,然后用体积分数为10%的H2SO4腐蚀镀层,使镀层中的Zn脱溶,成功得到多孔Pb-Zn电极,该镀层由铅(Fm3m)和锌（P63/mmc）的混合物组成。 采用循环伏安、阴极极化、计时电量及电化学阻抗等方法,研究了马来酸在多孔Pb-Zn电极和Pb电极上的电化学还原特性。 结果表明,马来酸在电极上先发生吸附,然后进行不可逆电子传递反应;马来酸在Pb电极和多孔Pb-Zn电极上还原的扩散系数分别为1.2×10-7和1.7×10-7 cm2/s;随着温度升高,马来酸在Pb电极上表观交换电流密度稳定性不如多孔Pb-Zn电极,多孔Pb-Zn电极上马来酸在低温处i0与温度呈线性关系,从50 ℃开始,i0急剧增加,至65 ℃,i0迅速下降,其在多孔Pb-Zn电极上电还原在50～60 ℃最好。 马来酸在多孔Pb-Zn电极比相应的Pb电极上具有更高的电催化活性。     

Cyclization of the Reaction Products of p-Phenylenediamine with Maleic Acid

Treatment of p-phenylenediamine with maleic acid and its diethyl ester gave di- and tetracarboxylic amino acids and their esters. A benzene derivative having an -alanine and an aspartic acid residue has been prepared. The cyclization of aminocarboxylic acids to imidazole and pyrimidine derivatives has been carried out.     

Isomerization of Maleic Acid to Fumaric Acid Catalyzed by Cerium(IV) and N-Bromo Compounds

Maleic acid (MA) in aqueous sulfuric acid undergoes catalytic isomerization in the presence of small amounts of Cerium(IV) ion and N-bromosuccinimide (NBS) or N-bromoacetamide (NBA). The rate of isomerization is very fast even at room temperature and the yield is quite acceptable. The rate of isomerization depends on the relative amounts of MA, Ce(IV), NBS, NBA, and H₂SO₄. However, maleic acid has greater effect on the final yield. Sulfuric acid exhibits more chemical effect than physical effects. The competitive redox reactions of Ce(IV), NBS, and NBA with MA limit the yield of isomerization to about 85%. In the vicinity of room temperature, a raise of five degrees in temperature nearly doubles the rate of isomerization. Acrylamide shows inhibitive effect on the isomerization. The rate of hydrolysis of NBS or NBA in aqueous acidic solution depends on the concentrations of hydrogen ion, and NBS or NBA itself. The rate of hydrolysis of NBA is much faster than that of NBS. Mechanism involving bromine atom as catalyst is proposed to explain experimental results.     

Self‐Assembly of Diblock Copolymers into Novel Snowflake‐Shaped Aggregates Driven by Quadruple Hydrogen Bonding

Two well‐defined diblock copolymers with quadruple hydrogen‐bonding groups on one block, denoted PSUEA‐1 and PSUEA‐2 , have been synthesized, and novel snowflake‐shaped nanometer‐scale aggregates, self‐assembled by such diblock copolymers in non‐polar solvents, have been observed. The micellar dimensions were investigated by DLLS and SLLS. Their morphologies were studied by TEM. Since the degrees of polymerization of the Upy‐containing blocks of PSUEA‐1 and PSUEA‐2 are quite similar and the polystyrene block of the PSUEA‐1 is longer than that of the PSUEA‐2 , a subtle but identifiable difference between the sizes and structures of the PSUEA‐1 and PSUEA‐2 aggregates was noticed and characterized.

     

Novel double hydrophilic block copolymers based on poly(p‐hydroxystyrene) derivatives and poly(ethylene oxide)

The synthesis of three series of double hydrophilic block copolymers (DHBCs), consisting of poly(ethylene oxide) as the neutral water soluble block and a second polyelectrolyte block of variable chemistry, is described. The synthetic scheme involves the anionic polymerization of poly(p‐tert‐butoxystyrene‐b‐ethylene oxide) (PtBOS‐PEO) amphiphilic block copolymer precursors followed by the acidic hydrolysis of the hydrophobic poly(p‐tert‐butoxystyrene) (PtBOS) block to an annealed anionic polyelectrolyte poly(p‐hydroxystyrene) (PHOS) block. The PHOS block was subsequently transformed into a high charge density annealed cationic polyelectrolyte namely poly[3,5‐bis(dimethylaminomethylene) hydroxystyrene] (NPHOS), via aminomethylation. Finally, the NPHOS block was transformed into a quenched polyelectrolyte, namely quaternized poly[3,5‐bis(dimethylaminomethylene) hydroxystyrene] (QNPHOS) block by reaction with CH₃I. The solution properties of the different series of the above block polyelectrolyte copolymers have been investigated using static, dynamic and electrophoretic light scattering, turbidimetry, and fluorescence spectroscopy. © 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 5790–5799, 2007     

The Influence of Crosslinking Amylose-Methacrylic Acid Graft Copolymers on the Release of BSA

Summary: One of the biggest challenges in the drug delivery field is to obtain oral systems for the release of peptides and proteins, enabling their use as therapeutic agents for clinical applications. The aim of this work is to obtain biodegradable copolymers suitable for the development of matrices which offer controlled release of proteins to be administered orally.Graft copolymers of amylose-methacrylic acid were synthesized using different amounts of the crosslinker N, N′-methylenediacrylamide. The influence on the release profiles of bovine serum albumin (BSA) was researched.