Electrosynthesis and physioelectrochemical properties of poly tyramine electroactive film in the presence of the surfactant: Comparable study

We describe in detail the advantages of a novel method of electrochemical preparation of poly tyramine (PT), based on the ability of anionic surfactants to form micelles in aqueous media. We demonstrate that the electropolymerisation process carried out in the presence of sodium dodecyl sulfate (SDS) at an oxidation potential lower than in an aqueous media yields better organized PT films. Theoretical calculations for tyramine (Ty) polymerization were carried out at density functional theory (DFT) level using the 6-31G(d,p) basis set. The improved physicochemical and structural properties of PT obtained in these conditions related to the electrocatalytic effect of SDS and change fractal dimension of the film. With respect to Ni-PT/G, Ni-SDS-PT/G electrode shows a higher catalytic performance for the electrocatalytic oxidation of methanol.     

表面活性剂对离子液体预处理纤维素的影响

采用离子液体1-甲基-3乙基咪唑磷酸二甲酯（[MEIM][DMP]）与表面活性剂耦合处理纤维素,考察表面活性剂对于酶解的影响,并用红外光谱、X射线衍射分析其机理。结果表明[MEIM][DMP]/聚乙二醇4000（PEG4000）处理的纤维素酶解率比未处理的纤维素高78.2%,比未加表面活性剂处理的再生纤维素高6.5%。红外光谱显示有PEG4000分子特征峰出现,X射线衍射分析表明PEG4000处理再生的纤维素几乎为无定形区。因此,PEG4000参与的处理有利于进一步提高纤维素酶解率,使结晶度降低,从而酶解率提高。     

Synthesis and characterization of new poly(ortho ester amidine) copolymers for nonviral gene delivery

A new type of pH-labile cationic polymers, poly(ortho ester amidine) (POEAmd) copolymers, has been synthesized and characterized with potential future application as gene delivery carriers. The acid-labile POEAmd copolymer was synthesized by polycondensation of a new ortho ester diamine monomer with dimethylaliphatimidates, and a non-acid-labile polyamidine (PAmd) copolymer was also synthesized for comparison using a triethylene glycol diamine monomer. Both copolymers were easily dissolved in water, and can efficiently bind and condense plasmid DNA at neutral pH, forming nano-scale polyplexes. The physicochemical properties of the polyplexes have been studied using dynamic light scattering, gel electrophoresis, ethidium bromide exclusion, and heparin competition. The average size of the polyplexes was dependent on the amidine:phosphate (N:P) ratio of the polymers to DNA. Polyplexes containing the acid-labile POEAmd or the non-acid-labile PAmd showed similar average particle size, comparable strength of condensing DNA, and resistance to electrostatic destabilization. They also share similar metabolic toxicity to cells as measured by MTT assay. Importantly, the acid-labile polyplexes undergo accelerated polymer degradation at mildly acid-pHs, resulting in increasing particle size and the release of intact DNA plasmid. Polyplexes from both types of polyamidines caused distinct changes in the scattering properties of Baby Hamster Kidney (BHK-21) cells, showing swelling and increasing intracellular granularity. These cellular responses are uniquely different from other cationic polymers such as polyethylenimine and point to stress-related mechanisms specific to the polyamidines. Gene transfection of BHK-21 cells was evaluated by flow cytometry. The positive yet modest transfection efficiency by the polyamidines (acid-labile and non-acid-labile alike) underscores the importance of balancing polymer degradation and DNA release with endosomal escape. Insights gained from studying such acid-labile polyamidine-based DNA carriers and their interaction with cells may contribute to improved design of practically useful gene delivery systems.     

对氯乙酰氨基酚的合成工艺研究与表征

以氯乙酸和二氯亚砜为原料用传统的方法合成氯乙酰氯,进而以其为酰化试剂,以对氨基酚为原料,在氯乙烷和乙酸乙酯溶剂中通过正交实验分别确定了氯乙烷为最佳溶剂和该反应的最佳反应条件为:以氯乙烷为溶剂时, n(对氨基酚)∶n(氯乙酰氯)∶n (溶剂)=1∶2.5∶9,反应温度80 ℃,反应时间3 h,最高收率为90%.同时进行了规律性实验和强化实验证明了上述最佳反应条件.并对所合成的产物进行了熔点测定、元素分析、质谱分析、红外光谱分析以及核磁共振氢谱分析,确定所合成的化合物即是目的产物.     

Influence of nonionic surfactant additive on the properties of ionic surfactant solutions

The interaction of sodium dodecyl sulfate with a nonionic surfactant (a block copolymer of ethylene oxide and propylene oxide) has been investigated by the measurement of conductivity, surface tension and viscosity. The break point on the equivalent conductivity-square root of concentration diagram which gives the critical micelle concentration (cmc) of sodium dodecyl sulfate became less definite by the addition of the nonionic surfactant, because of the decrease in conductivity below the cmc and increase above the cmc. The steep decrease in reduced viscosity took place in dilute concentration of sodium dodecyl sulfate solutions. In the surface tension vs. concentration diagram, the concentration at which the two linear portions of the curve intersect represents the cmc. The addition of nonionic surfactant decreases this crossed point of sodium dodecyl sulfate and finally obscures the crossed point. These reults are interpreted in terms of an interaction between sodium dodecyl sulfate and nonionic surfactant.     

Aqueous solution properties of a silicone surfactant and its mixed surfactant systems

The aqueous solution properties of a nonionic silicone surfactant of dimethylpolysiloxane and its mixed surfactant systems were studied. It was found that the silicone surfactant has a high surface activity and forms micelles in two steps: premicelles in dilute concentrations and polymolecular micelles above 3.7 × 10⁻⁷ mol dm⁻³. In mixed systems of the silicone surfactant with anionic hydrocarbon or fluorocarbon surfactant, weak intermicellar interactions were found. They are due to electrostatic interaction between hydrophilic groups of the respective micelles. Dye solubilization measurements showed that the solubilized amount of Yellow-OB is greater than predicted by ideal systems. Hydrazo-azo tautomerism is observed in fluorocarbon-silicone surfactant systems, while Yellow-OB is solubilized only in the azo-form in the hydrocarbon-silicone surfactant system.     

Gold electrodes modified with poly(4‐aminophenol): incorporation of nitrogenated bases and an oligonucleotide

BACKGROUND: Investigations of chemical modification of electrode surfaces and immobilization of nitrogenated bases and oligonucleotides are considered essential for the construction of DNA electrochemical nanodevices. Modification of gold electrode surfaces with poly(4‐aminophenol) was carried out in order to produce polymers capable of immobilizing purine bases and oligonucleotides. RESULTS: Gold electrodes coated with poly(4‐aminophenol) showed improved analytical characteristics and considerably enhanced the electrochemical signals associated with the detection of adenine and guanine by factors of ca 3 and ca 6, respectively, when compared with non‐coated gold surfaces. Impedance studies indicated higher charge transfer impedance to modified electrodes containing adenosine monophosphate. Atomic force microscopy images showed that nitrogenated bases have a strong influence over the morphology of the modified electrode surface. It was observed that the modified electrode containing guanine presents globular morphology. CONCLUSION: The modified electrodes increased the amplitude of the current signal of nitrogenated bases when compared to non‐coated gold surfaces and produced good response and peaks to the detection of an oligonucleotide. This work presents, for the first time, the electropolymerization of 4‐aminophenol on gold electrodes, as well as the detection of nitrogenated bases and an oligonucleotide incorporated on these modified electrodes. Copyright © 2007 Society of Chemical Industry     

Nanostructuration of ionic liquids in fluorinated matrix: Influence on the mechanical properties

In this work, a new method to prepare fluorinated coatings with mechanical properties enhanced has been developed. Pyridinium, imidazolium, and phosphonium ionic liquids have been synthesized and used as new synthetic building blocks in a polytetrafluoroethylene matrix. The strategy demonstrated using long alkyl chain cations provides an opportunity to prepare nanomaterials with a nanoscale structuration. The design of these new ionic and nanostructured materials is very dependent on the cation-anion combination of ILs. The morphology analyzed by transmission electronic microscopy (TEM) shows that it is clearly tuned by the chemical nature of ILs. The finest structuration leads to a dramatic compromise between stiffness and deformation of material. The small-angle X-Ray scattering (SAXS) shows the evolution of the ionic networks during the mechanical sollicitation.     

Synthesis of poly(4‐aminophenol) by horseradish peroxidase and the evaluation of its adsorptivity for silver ions

In this study, poly(4‐aminophenol) was successfully prepared by an enzymatic reaction in water, with its molecular weights ranging from 12,000 to 52,000. The polymerization of 4‐aminophenol produced high yields over a wide pH ranging from 4 to 10. In addition, poly(4‐aminophenol) was also used for silver‐ion adsorption because it was composed of amino and hydroxyl groups. We found that the adsorption capacity of poly(4‐aminophenol) was relevant to the time, pH value, temperature, and concentration of silver ions, and the greatest adsorption capacity of poly(4‐aminophenol) for silver ions was 220 mg/g. Moreover, a series of tests showed that the adsorption of silver ions was mainly achieved by a reduction reaction, and the silver nanoparticles were formed with a face‐centered cubic structure, and their average particle size was about 10 nm. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40367.     

The effect of local residual stress on the fractal dimension of silicate glasses

Local residual stress caused by impacts, machining and indentation results in a decrease in strength in most materials that fail in a brittle manner. The ratio of the critical crack size, c, and the fracture mirror size, r, also is affected by the existence of local residual stress. The global fracture toughness of non-R curve materials is not affected by the local residual stress. The fractal dimension of the fracture surface as characterized by the fractal dimensional increment, D*, is directly related to the square of the fracture toughness. This paper addresses the question of the effect of the local residual stress on the fractal dimension of the fracture surface. We derive a relationship between the fractal dimensional increment and the c/r ratio for materials fractured with and without local residual stress. We then compare the prediction with two cases of experimental results. We show the fractal dimension remains constant with the change in the c/r ratio for local residual stress conditions.     

盐对阴阳离子表面活性剂水溶液相行为的影响

以阴阳离子表面活性剂混合体系为研究对象,通过测定体系在不同种类盐溶液中的三元相行为,探索了盐对体系相行为中的双水相区位置及相区宽度的影响规律.研究发现,阴离子双水相区的位置与宽度主要受盐阳离子的影响,盐阳离子半径越大,极化率越高,阴离子双水相区向阴离子表面活性剂方向移动的趋势越大,相区越宽;而盐的阴离子是影响阳离子双水相区位置与宽度的主要因素.     

The influence of frequency on fractal dimension of adsorbed layers

Alternating current (AC) voltammetry and electrochemical impedance spectroscopy are often the methods of choice for use in study of adsorption of organic molecules. The adsorption of organic molecules on interface may result in the formation of fractal structures, whose fractal dimension can be estimated using the method of scaling the hanging mercury drop electrode (HMDE). The aim of present study was to check whether the estimated fractal dimension, D (or for that matter the fractal ordering of the adsorbed layer) shows any correlation (dependence) with change of applied frequency, and second, to check the possibility to extend the method to broad frequency spectrum compatible with impedance spectroscopy. The investigation included two surfactants nonionic Triton-X-100 (T-X-100) and anionic sodium dodecyl sulfate (SDS) and alcohol tert-butanol. All measurements were performed on HMDE at thermodynamic equilibrium employing broad frequency spectrum. The validity of the approach was checked by measurements on pure electrolyte and by comparison with previously obtained results for fractal layers. The results of the investigations show that: (1) the method of scaling the HMDE to obtain the fractal dimension of adsorbed layer is compatible with impedance spectroscopy and the combination of these methods can be used as a powerful tool to investigate fractal aspect of adsorption of organic molecules; (2) fractal ordering of adsorbed layer and the value of fractal dimension is not influenced by the frequency of applied sinusoidal voltage perturbations.     

Electrodeposition of macroporous silver films from ionic liquids and assessment of these films in the electrocatalytic reduction of nitrate

Macroporous silver films, ordered or fragmented, were fabricated by electrodeposition of silver into the interstitial spaces of templates formed by polystyrene (PS) latex spheres that had been self-assembled onto bare indium tin oxide (ITO) electrodes or onto gold-coated ITO (ITO/Au) electrodes (in which the electrode had been coated by gold sputtering deposition) from two room-temperature ionic liquids (ILs): N-butyl-N-methylpyrrolidinium bis(trifluoromethanesulfonyl)imide (BMP-TFSI) and N-butyl-N-methylpyrrolidinium dicyanamide (BMP-DCA), respectively, under normal atmospheric conditions. After electrodeposition of silver, the PS spheres were removed by dissolution in tetrahydrofuran (THF) to leave a macroporous silver structure. The higher wettability of ILs onto PS spheres leads to improved penetration of the ILs into the cavities of the PS templates. Electrodeposition is easier if an electrolyte that has a good penetration into the interstitial spaces between the PS spheres. The macroporous silver electrode exhibited much better electrocatalytic performance with respect to nitrate reduction than a regular silver wire electrode. Quantitative determination of nitrate was also examined.     

一种新型双子表面活性剂的合成与性能

以丙酮为溶剂的条件下,顺丁烯二酸酐、乙二醇、己醇酯化后经磺化合成新型的gemini型磺基琥珀酸盐表面活性剂。反应的较佳工艺条件为:催化剂用量为顺酐质量的1%,n(顺酐)∶n(乙二醇)=2.05∶1,于70℃下单酯化反应2.0 h,得到酯化率约94.6%的单酯化产物;n(己醇)∶n(顺酐)=1.15∶1,160℃下双酯化反应40 min,可得到酯化率约95%的双酯化产物;n(NaHSO3)∶n(顺酐)=1.05∶1,110℃下反应2.5 h,可得到磺化率99.5%的目标产物。合成的样品显示出优良的表面活性和较好的乳化、润湿、渗透、去污等应用性能,是一种较为理想的表面活性剂。     

Influence of surfactant properties on thermal behavior and sol–gel transitions in surfactant‐HPMC mixtures

Four surfactants, namely, sodium n‐decyl sulfate (SDeS), sodium n‐hexadecyl sulfate (SHS), sodium n‐dodecyl sulfate (SDS), and Triton X‐100, were used as additives to study thermal behavior and sol–gel transformations in dilute aqueous hydroxypropyl methyl cellulose (HPMC)/surfactant mixtures using micro‐differential scanning calorimetry. The influence of anionic surfactant, SDS on the gelation varied with SDS concentration where the sol–gel transition started at a higher temperature. Shape of the thermograms changed from single mode to dual mode at the SDS concentration of 6 mM and higher. SDeS and SHS, however, resulted in “salt‐in” effect of a different magnitude during gelation. Triton X‐100, being a non‐ionic surfactant, showed a minor “salt‐out” effect on the thermo‐gelation process. On the basis of different thermal behavior of anionic and non‐ionic surfactant/HPMC systems, a mechanism is proposed explaining how the chemical structure and electro‐charge of the surfactants affect the polymer/surfactant binding and polymer/polymer aggregation because of hydrophobic interaction during the sol–gel transition. © 2009 Wiley Periodicals, Inc. Journal of Applied Polymer Science, 2009     

HTM-12表面活性剂的合成及表面活性

以无水对氨基苯磺酸、1,4-二溴丁烷合成了N,N’-(二对苯磺酸)丁二胺,再与溴代十二烷反应合成N,N’-(十二烷基二对苯磺酸钠)丁二胺(简称HTM-12),合成了带有两个疏水长链的双磺酸盐表面活性剂。该产物水溶液的cmc(7.0×10-4mol/L)是SDBS和DTAB的1/14和1/23,γcmc(26.8 N/m)分别比SDBS(39.0 mN/m)和DTAB(38.9 mN/m)低12.2 mN/m和12.1 mN/m。HTM-12和DTAB复配产生了明显的协同效应。在实验范围的任意配比条件下,HTM-12/DTAB体系的表面活性比SDBS/DTAB高得多。HTM-12∶DTAB=3∶7(摩尔比)时,复配体系的cmc为2.15×10-4mmol/L,γcmc=22.3 mN/m;与SDBS/DTAB的最优化配比(1∶1)相比较,cmc仅为后者的1/3.5,γcmc低10.8 mN/m。     

表面活性剂HD驱油体系性能研究

在表面活性剂提高采收率原理基础上,对HD界面特性及岩心驱油实验进行了研究。结果表明,在一定条件下,HD浓度在0.025%～0.30%的较宽范围内均可使矿化度为6 823 mg/L的油田污水形成10-3mN/m数量级的超低界面张力。同时,加入适量添加剂HDSY,使达到最低界面张力的时间缩短(原来40 min,现为15 min)到原来的63.5%,且效果均优越于单一HD体系。复合体系驱替实验结果表明,在水驱含水达95%以后,还可继续提高原油采收率24.25%。     

杯芳烃基低聚表面活性剂的合成与表面性能

以对叔丁基苯酚、甲醛为主要原料合成杯芳烃母体对叔丁基杯[n]芳烃(n=4,6,8);以1,3-丙烷磺内酯、1,4-丁烷磺内酯为醚化试剂,经Williamson醚化反应,合成出6种杯芳烃基低聚表面活性剂。利用IR表征了中间体和最终产物的结构,确定了化合物的结构与所设计的分子结构相同。用染料法对所合成产物进行了定性鉴定,并用滴体积法测定了表面活性剂水溶液25℃时的表面张力。结果表明,随着杯芳烃空腔的逐渐增大,cmc值降低,γcmc值升高,Γcmc值下降,Am值升高。     

An investigation of silver electrodeposition from ionic liquids: Influence of atmospheric water uptake on the silver electrodeposition mechanism and film morphology

The electrodeposition of silver from two ionic liquids, 1-butyl-3-methylimidazolium tetrafluoroborate ([BMIm][BF₄]) and N-butyl-N-methyl-pyrrolidinium bis(trifluoromethanesulfonyl)imide ([C₄mPyr][TFSI]), and an aqueous KNO₃ solution on a glassy carbon electrode was undertaken. It was found by cyclic voltammetry that the electrodeposition of silver proceeds through nucleation–growth kinetics. Analysis of chronoamperometric data indicated that the nucleation–growth mechanism is instantaneous at all potentials in the case of [BMIm][BF₄] and [C₄mPyr][TFSI], and instantaneous at low overpotentials tending to progressive at high overpotentials for KNO₃. Significantly, under ambient conditions, the silver electrodeposition mechanism changes to progressive nucleation and growth in [C₄mPyr][TFSI], which is attributed to the uptake of atmospheric water in the IL. It was found that these differences in the growth mechanism impact significantly on the morphology of the resultant electrodeposit which is characterised ex situ by scanning electron microscopy and X-ray diffraction.