Properties of Didecyldimethylammonium Formate and Sodium Fatty Alcohol Ether Carboxylate Mixed Systems

The surface activities and application properties of didecyldimethylammonium formate (DDAF) and sodium fatty alcohol ether carboxylate (AEC-9Na) mixed systems were measured. The results showed that the critical micelle concentration and surface tension of mixed systems have lower values than that of a single surfactant solution, which is attributed to the synergism of DDAF and AEC-9Na. It was found that the emulsifying properties for kerosene and wetting properties of the mixed systems were also better than single component surfactants. In addition, the mixed systems of AEC-9Na (16 wt%) with DDAF showed both better detergency and excellent antibacterial properties.     

Characterization,surface properties and biological activity of new prepared cationic surfactants

Three cationic surfactants were prepared. A condensation reaction between dimethylaminopropylamine (DMAPA) and benzaldehyde was performed. The produced Schiff base was quaternization with three fatty alkyl bromide with different carbon chain length separately to form the desired cationic surfactants. The chemical structure of synthesized cationic surfactants was confirmed by FTIR, ¹H NMR and mass spectroscopy. It was found that the chemical structure of prepared compounds has an effect on surface properties, where increasing the hydrophobic chain length decrease the values of CMC, Г_max while A_min value was increased. The thermodynamic parameters showed that adsorption and micellization processes are spontaneous. It is clear that the prepared cationic surfactants at first tend to adsorb at surface, then it aggregate to form micelle. The prepared surfactants showed good biological activity against gram positive and negative bacteria and fungi in the following order of II (C12) > I (C10) > III (C16). The serial dilution method was used to evaluate the inhibiting effect of these compounds on the sulfate reducing bacteria growth.     

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.     

Synthesis,surface, thermodynamic properties and Biological activity of dimethylaminopropylamine surfactants

The chemical structure of the prepared cationic surfactants which formed through condensation reaction between dimethylaminopropylamine (DMAPA) and butyraldehyde then quaternized by three fatty alkyl bromide was confirmed by FTIR, ¹HNMR and mass spectroscopy. The chemical structure of prepared compounds has an effect on surface properties. By increasing the hydrophobic chain length, the values of CMC and Г_max decrease while A_min value was increased. The Thermodynamic parameters showed that adsorption and micellization processes are spontaneous. It is clear that the prepared cationic surfactants tend to adsorb at surface, then it aggregate to form micelle. The prepared surfactants showed good biological activity against Gram-positive and negative bacteria and fungi. The prepared cationic surfactant showed aggressive effect on the sulfate reducing bacteria growth.     

二聚离子表面活性剂/醇混合胶团组成的计算

二聚离子表面活性剂/醇在水溶液中相互作用,生成混合胶团。以Motomura理论为基础,给出混合胶团组成的计算公式,以此计算了二聚季铵盐表面活性剂/低碳醇混合胶团的组成,并进行了讨论。     

Polymer-Induced incompatibility in the mixed micelle formation of cationic surfactants with bulky polar head groups

The conductances of tetradecyltrimethylammonium bromide (TTAB)+tetradecyl triphenylphosphonium bromide (TTPB) mixtures over the entire mole fraction range were measured in aqueous poly(vinyl pyrrolidone) (PVP) containing 1 to 10 wt% of PVP at 30°C. Each conductivity (κ) curve showed a single break corresponding to the mixed micelle formation in the presence of PVP over the whole mole fraction range. From the conductivity data, various micellar parameters in the presence of PVP were computed and discussed in terms of micelle-polymer interactions. The mixing behavior of TTAB+TTPB in pure water was close to ideal, whereas in the presence of PVP a significant degree of nonideality was sobserved that was evaluated by computing the mole fraction of TTAB in the mixed micelle state (x ₁) and the interanction parameter (β) by using the regular solution approach. The former is less than the value in the ideal state, and the latter is much greater, indicating the enhancement in the antagonistic mixing behavior of TTAB+TTPB in the presence of PVP. The results have been explained on the basis of an increase in the incompatibility between the monomers of TTAB and TTPB in the mixed state due to the steric hindrances created by the PVP upon adsorption at the micelle-solution interface. The results have also been further supported by comparing with those of structurally similar cationic binary combinations in the presence of PVP.     

Study of the influence factors on the synthesis of Fe-MCM-48 with binary mixed cationic and anionic surfactants

Highly ordered Fe-MCM-48 was synthesized by a mixed template method under low molar ratio (0.17:1) of mixed surfactants to silica. The effect of various factors, such as Fe sources, the amount of Fe salt, Si sources, surfactant/SiO₂, crystallization temperature and crystallization time on the synthesis were discussed in detail. The Debye-Huckel theory, the theory of salts formation, the local effective surfactant packing parameter theory and the charge balance theory were used to explain the reason that various factors can affect the product structure reasonably. The optimum synthesis conditions for Fe-MCM-48 were obtained.     

Solubilization of octafluoronaphthalene by mixed micelles of fluorocarbon and hydrocarbon surfactants in aqueous solutions

Solubilization of octafluoronaphthalene (OFN) by fluorocarbon and hydrocarbon surfactants in aqueous solutions has been examined to investigate the effects of mixing surfactants and added salt. Diethylammonium perfluoronanoate (DEAPFN) micelles have the most solubilization power toward OFN. The difference in micellar solubilization power will be caused by the hydrophobicity of ionic groups and micellar size. Large positive synergistic effects on solubilization behavior were observed in the DEAPFN-diethylammonium tetradecyl sulfate mixed micellar systems. Solubilization of OFN depended on the concentrations of added salt and the aggregation number, that is, the micellar size.     

Enhancement of the activity of papain in mixed reverse micellar systems in the presence of Tween80

An enhancement in the activity of papain (EC 3.4.22.2) was described in mixed reverse micellar systems containing Tween80 compared with those without Tween80. By the use of these media, the hydrolytic and synthesis activities of papain were investigated in detail, respectively for the hydrolysis of N‐α‐benzoyl‐L ‐arginine‐p‐nitroaniline (BNPNA) and the synthesis of the dipeptide Z‐Gly‐L ‐PheOMe (ZGPM). The reaction medium conditions (W₀, pH and Tween80 concentration) were optimized for both the hydrolytic and synthesis reactions. The results showed a pronounced increase in the papain activity when a moderate amount of Tween80 was added into sodium di‐2‐ethylhexylsulfosuccinate (AOT) or tetradecyltrimethylammonium bromide (TTAB) reverse micelles, either in the yield of dipeptide synthesis or in the initial rate of BNPNA hydrolysis. In addition, a mechanism to explain the enhancement of enzymatic activity was proposed according to the change of the optimal parameters in the mixed and non‐mixed reverse micellar systems, which is associated with the environmental polarity surrounding the solubilised enzyme molecules. © 2001 Society of Chemical Industry     

The physicochemical properties of the mixed solvent of 2-piperidineethanol,sulfolane and water

The physicochemical properties of the mixed solvent of 2-piper-idineethanol (2-PE), sulfolane (TMS) and water were determined over a wide range of temperatures and compositions. The density, the viscosity and the dissociation constant, as well as the solubility of N₂O in this mixed solvent were correlated as a function of temperature and composition over the entire experimental range. The models are useful not only for the ternary solvent system, but also for the binary solvent systems, such as 2-PE+H₂O and TMS+H₂O. From the regression, it has been found that the interaction of aqueous 2-PE solution and aqueous TMS solution is negligible.     

Drag reduction in turbulent pipeline flow of mixed nonionic polymer and cationic surfactant systems

Turbulent drag reduction behaviour of a mixed nonionic polymer/cationic surfactant system was studied in a pipeline flow loop to explore the synergistic effects of polymeric and surfactant drag reducing additives. The nonionic polymer used was polyethylene oxide (PEO) at three different concentrations (500, 1000, and 2000 ppm). The surfactant used was cationic octadecyltrimethylammonium chloride (OTAC) at concentration levels of 1000 and 2500 ppm. Sodium salicylate (NaSal) was used as a counter‐ion for the surfactant at a molar ratio of 2 (MR = Salt/OTAC = 2). Relative viscosity and surface tension were measured for different combinations of PEO and OTAC. While the relative viscosities demonstrated a week interaction between the polymer and the surfactant, the surface tension measurements exhibited negligible interaction. The pipeline results show a considerable synergistic effect, that is, the mixed polymer–surfactant system gives a significantly higher drag reduction (lower friction factors) as compared with pure polymer or pure surfactant. The addition of surfactant to the polymer always enhances drag reduction. However, the synergistic effect in mixed system is stronger at low polymer concentrations and high surfactant concentrations. © 2011 Canadian Society for Chemical Engineering     

Influence of accelerator/sulphur and co-agent/peroxide ratios in mixed vulcanisation systems on cure characteristics,mechanical properties and heat aging resistance of vulcanised SBR

The influence of accelerator/sulphur and co-agent/peroxide ratios on cure characteristic and vulcanisate properties in mixed vulcanisation of styrene butadiene rubber (SBR) was investigated in this work. Accelerator/sulphur ratio was investigated with three alternative sulphur curing systems, namely conventional, semi-efficient and efficient vulcanisation (EV) systems. Zinc dimethacrylate (ZDMA) was used as a co-agent to enhance the performance of peroxide and to provide ionic linkages. Ionic linkages contributed by ZDMA create bridges between two polymer chains. The ZDMA/peroxide ratio was varied from 2 to 10. The concentration of dicumyl peroxide was held fixed while the ZDMA content was varied. Cure characteristics, mechanical properties, dynamic mechanical properties and heat aging resistance were investigated in relation to the crosslink structure. Increasing the ZDMA/peroxide ratio significantly increased density of ionic linkages, especially in combination with the EV system. The combination of EV system with high ZDMA/peroxide ratio provided the highest ionic crosslink density and the lowest polysulphidic crosslink density: this enhanced the mechanical properties, the dynamic mechanical properties and the thermal stability of SBR vulcanisates.     

Influence of breakup and reformation of micelles on surfactant diffusion in pure and mixed micellar systems

Pulsed field gradient (PFG) NMR technique was used to study diffusion of surfactant ions in the following two micellar systems: (i) aqueous solution of an anionic surfactant sodium dodecyl sulfate (SDS), and (ii) aqueous solution of a mixture of SDS and a small amount of the cationic surfactant N-dodecyltrimethylammonium bromide (C₁₂TAB). PFG NMR measurements provided separate sets of data on diffusion of SDS and C₁₂TAB surfactant ions for a broad range of diffusion times. For each type of surfactants at least two components with different effective diffusivities were observed at sufficiently small diffusion times. The faster component was assigned to the surfactants that experience breakup or reformation of micelles during the diffusion time of the PFG NMR measurement, while the slower component was assigned to the surfactants that did not participate in such events during the diffusion time. The observed changes of the fractions and diffusivities of these components with increasing diffusion time were found to be in a qualitative agreement with such assignment. Fundamental understanding of surfactant diffusion in micellar system is important due to an increasing use of such systems for synthesis of porous materials where micelles are used as templates as well as for many other applications.     

Reactive surfactants in heterophase polymerization. XVII. Influence of the surfactant on the mechanical properties and hydration of the films

In the context of a European union‐supported network on “Reactive Surfactants for Heterophase Polymerization,” different polymerizable surfactants (surfmers) have been synthesized and engaged in the emulsion polymerization of styrene, butyl acrylate, and acrylic acid. The thermomechanical properties of films cast from these different latices are reported in this article. The evolution of the mechanical properties with temperature and the effect of water molecules on these properties are studied. We observed that the studied surfactants do not influence the properties of the dry films. However, some differences due to grafting of reactive surfactants appeared when the films were wet. The amount of water uptake is drastically decreased when only reactive surfactants are present in the film. Concerning the mechanical behavior of the wet films, a decrease of the plastic flow stress is observed for all the samples whatever the nature of the surfactant (reactive or conventional). Hence, calorimetric measurements and dynamic mechanical analysis are used to identify the possible mechanisms that induce the change in the mechanical behavior of the latex films. In the case of reactive surfactant grafted to the polymer, the very low value of water uptake is accompanied by a plasticization of the polymer. In contrast, no plasticizing effect is observed in the case of nonreactive surfactant, even if the amount of water is very large. Finally, the tensile behavior of the styrene–butyl acrylate copolymer versus temperature is analyzed in the frame of the quasi point defects (qpd) model. Both rubber elasticity and chain orientation effects are taken into account to describe the behavior laws at large extensions (i.e., ? ≈ 1.2). © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 84: 1686–1700, 2002; DOI 10.1002/app.10548     

复配表面活性剂对油水界面行为和性质影响的模拟研究

含复配表面活性剂的油田废水是一种多组分复杂体系,研究其中的分子作用关系有助于后续废水处理方案的确定。采用分子动力学(MD)模拟方法建立界面模型,通过定义表面活性剂的关键扭转点及相应的分子夹角、定义协同作用能,结合界面处的密度分布函数等性能模拟和界面张力测试结果,多角度分析两类阴阳离子表面活性剂复配对油水界面特性的影响。结果表明,与含单组分表面活性剂的油水体系相比,复配表面活性剂的相反电荷极性头基间静电吸引作用提高了油水界面稳定性;相较于十二烷基磺酸钠/十六烷基三甲基溴化铵(SLS/CTAB)复配体系,十二烷基硫酸钠/十六烷基三甲基溴化铵(SDS/CTAB)中分子间的协同作用可更好地提高体系的稳定性;当复配表面活性剂的配比为8/10~12/6时的油/水界面稳定效果较优、12/6时稳定性最好。研究结果可为石油开采及油水分离方案的确定提供依据。     

复配表面活性剂对油水界面行为和性质影响的模拟研究

含复配表面活性剂的油田废水是一种多组分复杂体系,研究其中的分子作用关系有助于后续废水处理方案的确定。采用分子动力学(MD)模拟方法建立界面模型,通过定义表面活性剂的关键扭转点及相应的分子夹角、定义协同作用能,结合界面处的密度分布函数等性能模拟和界面张力测试结果,多角度分析两类阴阳离子表面活性剂复配对油水界面特性的影响。结果表明,与含单组分表面活性剂的油水体系相比,复配表面活性剂的相反电荷极性头基间静电吸引作用提高了油水界面稳定性;相较于十二烷基磺酸钠/十六烷基三甲基溴化铵(SLS/CTAB)复配体系,十二烷基硫酸钠/十六烷基三甲基溴化铵(SDS/CTAB)中分子间的协同作用可更好地提高体系的稳定性;当复配表面活性剂的配比为8/10~12/6时的油/水界面稳定效果较优、12/6时稳定性最好。研究结果可为石油开采及油水分离方案的确定提供依据。     

Spontaneous Vesicle Formation in Mixtures of Quaternary Ammonium Compounds with Carbamate and Sodium Dodecylbenzene Sulfonate

Spontaneous vesicles formation in the aqueous mixtures of 2,3‐bis (dodecylcarbamoyloxy)‐N, N‐dimethyl‐N‐(2‐hydroxyalkyl) propyl ammonium chloride (C₁₂PAC) and sodium dodecylbenzene sulfonate at different mixing molar ratios have been investigated. The characterizations are demonstrated by electrical conductivity measurements, dynamic light scattering and zeta (ζ) potential measurements. The ζ‐potential results indicate the C₁₂PAC/SDBS systems are stable. The shapes of the catanionic vesicles are observed by negative‐staining transmission electronic microscopy. Meanwhile, from the viewpoint of molecular geometry structure, the electrostatic interaction between anionic and cationic molecules is regarded as the main driving force for spontaneous formation of vesicles.     

Comparison of the effects of oven- and microwave-roasting on the physicochemical properties and bioactive compounds of tomato seeds and oils

The tomato processing industry generates a significant amount of a by-product (pomace), which is a mixture of peels and seeds. The purpose of this study was to compare the effects of conventional oven-roasting (at 120°C, 150°C, and 180°C for 25 min) and innovative microwave-roasting (at 240, 388, and 536 W for 3 min) pretreatments on the physicochemical properties, fatty acid profiles, bioactive contents, and aroma profiles of tomato seeds and their hexane-extracted oils. The total flavonoids contents (TFCs) of the seeds decreased from 258.40 to 141.20 mg quercetin equivalent (QE) per kg after roasting. All roasting treatments improved the extractability of both α- and γ-tocopherols. The amounts of total tocopherols in the seeds increased from 917.61 to 1256.25 mg kg^–1 after pretreatment. Luteolin was found to be the most abundant phenolic in seed oils, increasing from 10.68 to 91.72 mg kg^–1, followed by quercetin, ferulic acid, and catechin. Within each roasting technique, the ones treated at 150°C and 338 W yielded the oils with the highest concentrations of aroma compounds, 418 and 92 mg kg^–1, respectively. The detrimental effect of microwave-roasting on these compounds was more pronounced. In conclusion, microwave-roasting at shorter times than conventional roasting produced tomato seed oils with well-preserved bioactive components and few unfavorable changes. Industrial relevance: Conventional oven-roasting has been widely applied to oilseeds to improve oil yield as well as to obtain desirable sensory characteristics of extracted oils for years. However, longer roasting times may also cause detrimental changes in the properties of oils. On the other side, microwave-assisted applications as an emerging technology provide homogenous and well-controlled heat distribution, shorter treatment times, and considerable energy savings for the processing of various foods. Microwave technology has been easily scaled up and is currently employed for sterilization, drying, pasteurization, precooking, and extraction by the food and chemistry industries. Therefore, the present research suggests the use of microwaves for comparatively short roasting times to produce edible oils with enhanced physicochemical attributes and bioactives contents, and well-maintained sensory properties. This promising innovative technology has the potential to be industrialized for a cost-effective seed roasting process.     

Influence of ceramic phosphate powders on the physicochemical and biological properties of poly(l-lactide)

In the present work, the attention is focused on cannulated, biodegradable olives made of poly(l-lactide) (PLLA) and PLLA with the addition of phosphate ceramics. The olive is an element expanding the intramedullary nail intended to be implantation the humerus bone. During degradation, the olive reduces the diameter of the nail, while ensuring the best conditions for the growth of bone tissue. The article examines the effect of the addition of tricalcium phosphate (β-TCP) and hydroxyapatite (HAp) on morphology, chemical structure, physicochemical and biological properties of PLLA during storage in a degradation medium imitating the natural environment of the human body. The introduction of β-TCP+HAp into PLLA led to significant changes in both surface morphology, chemical structure and physicochemical properties, which contributed to the faster course of the biodegradation of the orthopedic implant. Due to this process, it was found that the PLLA composite with phosphate ceramics can be successfully used in this application. Clinical studies have shown that the implantation of olive made of PLLA+β-TCP+HAp does not cause any negative systemic reactions. The orthopedic implant was biodegradable and significantly contributes to bone union.     

Effects of the doping concentration of boron on physicochemical,mechanical, and biological properties of hydroxyapatite

Ion doping is an approach to modify properties of materials, like hydroxyapatite (HA), that contributes to designing biomaterials with desired characteristics applicable in bone defect treatments. Recently, boron (B) has been noticed in biomaterial fields due to its beneficial effects on formation, growth, and quality of bone. In this study, B-doped HA nanoparticles with different molar concentrations of B (0.05, 0.1, 0.25, and 0.5) were synthesized through microwave-assisted wet precipitation. The effects of B content on various properties of HA were evaluated. The results demonstrated that the size of HA particles reduced from 106 nm to 89-85 nm in B doped materials. Meanwhile, the crystallinity degree of B doped HA (BHA) samples was between 89.90% and 93.77%, compared to 95.19% of HA. Diametral tensile strength of samples was measured in the ranges of 2.51 and 3.61 with no significant difference among groups. The micro-hardness of HA was 0.88 GPa, whilst doped ones had hardness values of 0.5 GPa–0.68 GPa. Biodegradability of samples increased from less than 1% to approximately 4% after 28 days, while B-doping did not make any change in the degradation rate. Doping dosages were appropriate in terms of bioactivity and cell viability, and B doping caused higher bioactivity and cell proliferation. All changed properties were dose-dependent and more effective in doped groups with a higher amount of B. Despite proliferative effect, 260 μg/l and 770 μg/l of B release in two groups with the highest dopant concentrations did not positively influence the osteogenic activity of cells. Our results demonstrated that doping concentrations that resulted in B release ≤260 μg/l seem more appropriate dosage, especially for bone tissue engineering and substitute applications due to promoted bioactivity and proliferation, as well as no obstructive effects on mechanical properties and osteogenic activities of HA.