Octadecyltrimethylammonium Bromide Research Articles

Preparation and characterization of exfoliated nanocomposite of polyvinyl acetate and organic montmorillonite

AbstractTo improve the chemical, physical, and mechanical properties of polyvinyl acetate (PVAc), an organic montmorillonite (OMMT) was first prepared by montmorillonite (MMT) and octadecyl trimethyl ammonium bromide (STAB), and then it was added to synthesized PVAc under conventional laboratory conditions. The influence of its variable addition on the properties of PVAc—OMMT was investigated mainly by X‐ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), transmission electron microscopy (TEM), and static tension, and the rheology was also investigated by the power‐law function equation and the Cross–Williamson model viscous equation. The exfoliated nanocomposite of PVAc—OMMT was obtained; linear macromolecular chains of PVAc were formed in the layers of OMMT, and no chemical bonding appeared between OMMT and PVAc, but there were some physical effects. The dispersion of PVAc—OMMT was better than PVAc. OMMT was exfoliated into layers or sheets of nanoparticles and was randomly dispersed in the matrix of PVAc. The particle diameter of OMMT ranged from 50 to 100 nm, whereas PVAc's diameter ranged from 250 to 500 nm; the smaller OMMT particles were adsorbed around the bigger all PVAc particles and formed a “strawberry” structure. PVAc and PVAc—OMMT were both pseudoplastic non‐Newtonian fluids; they possessed the normal stress effect (or the Weissenberg effect), that is the pole‐climbing phenomenon. The static tension properties of PVAc—OMMT were much better than PVAc, and the addition of OMMT in polymerization was reasonable and not more than 2.0% of VAc. © 2011 Wiley Periodicals, Inc. Adv Polym Techn 32: 130–140, 2012; View this article online at wileyonlinelibrary.com. DOI 10.1002/adv.20244

Thermal-stability of mixed giant micelles of alkyltrimethylammonium surfactants and salicylate

When diluted solutions of giant micelles are under turbulent flow, large attenuations of the turbulence can be observed due to the action of the micelles on the dissipative vortices formed within the flow. This particular property is rapidly lost when the solution is heated due breakup of the giant micelles. Based on this property, we present a thermal-flow study of a mixed giant micelle formed by the combination of two surfactants and sodium salicylate. One of the surfactants, cetyltrimethylammonium bromide (C16TAB) was kept fixed, and the others were dodecyltrimethylammonium bromide (C12TAB), tetradecyltrimethylammonium bromide (C14TAB), octadecyltrimethylammonium bromide (C18TAB), polyoxyethylene (10) oleyl ether (Brij 97) or sodium dodecyl sulfate (SDS). Thermal diagrams for the combinations of the surfactants reveal deviations of the ideality. For the cationic surfactants, a synergistic effect was only observed when C16TAB was combined with the shorter surfactants.

Exploring the structure of inter-platelet galleries in organically modified montmorillonite using the small-angle X-ray scattering interface distribution function approach

Small-angle X-ray scattering interface distribution function (IDF) analysis is successfully applied to evaluate the two- and three-phase inter-platelet gallery structure in synthetic montmorillonite (MMT) modified with a mixture of chemically grafted and physically adsorbed chains of a typical organic modifier, octadecyl trimethyl ammonium bromide. Two distinctly different states of adsorbed chains in the inter-platelet galleries are identified. The first one corresponds to a fully cation-exchanged structure with an inter-platelet distance of about 21 Å. In this case the organic modifier is in a liquid-like state, and the system does not exhibit any structural or thermal transitions between ambient temperature and 433 K. When the number of adsorbed chains exceeds the cation-exchange capacity of the MMT platelets the inter-platelet spacing is increased to 43 Å. In this case, the variable-temperature IDFs reveal partially crystalline order in the inter-platelet galleries, which vanishes at the melting point of the alkyl tails confined in the galleries.

Cleaning secondary effluents with organoclays and activated carbon

AbstractBACKGROUND: Flocculation, adsorption and ultrafiltration, alone and in combination, were tested for tertiary treatment of Beer Sheva (southern Israel) municipal wastewater. The focus was on the adsorption of soluble organics with powdered activated carbon (PAC) and with organoclays.RESULTS: Adsorption on 0.6 g L−1 octadecyltrimethylammonium bromide (ODTMA) ‐ bentonite and flocculation with 130 mg L−1 FeCl3 reduced the dissolved organic carbon (DOC) level by 46%, and that was the highest DOC retention obtained with the organoclays. Retention achieved with 0.6 g L−1 PAC and 130 mg L−1 FeCl3 was 65%. Filtration through a more hydrophobic PVDF‐30 membrane for 30 min resulted in 35–40% flux drop. A reasonable 6–7% flux reduction was obtained with filtration through a more hydrophilic PS‐50 membrane.CONCLUSION: Oganoclays at low doses are a good target adsorbent for single low molecular weight molecules. On average, higher TOC retention was achieved with PAC. Introduction of adsorption as a pre‐treatment step can lead to minimization of flux losses, reduced demand for flocculation and improved economics of the entire treatment. Copyright © 2011 Society of Chemical Industry

Effects of Bentonite Modified by Organic Additives on the Physical Stability of Hexaconazole Suspension

Four kinds of quaternary ammonium salt cationic surfactants(dodecyl benzyl dimethyl ammonium chloride(1227),tetradecyl dimethyl benzyl ammonium(1427),hexadecyl trimethyl ammonium bromide(1631) and octadecyl trimethyl ammonium bromide(1831)) were used to modify sodium bentonite(Na-Ben).The prepared organic bentonites(1227-Ben,1427-Ben,1631-Ben,1831-Ben) were characterized by Fourier transform infrared spectroscopy(FT-IR) and X-ray diffraction(XRD),and used as subsidence-resistance for preparing suspensions containing 5% hexaconazole.The suspension capability of bentonite modified by above four organic additives in water and the effects of these bentonites on the physical stability of suspensions were examined.FT-IR spectra and XRD analysis results showed that these four cationic surfactants were intercalated into the layer of bentonite.Suspension capability results indicated that 1831-Ben has a better suspension than the other three.Subsidence-resistance tests showed that bentonites modified by organic additives could improve the physical stability of suspensions.The water segregation ratio of samples prepared by 1831-Ben was the lowest,while the viscosity,yield value and suspension rate were the highest.So 1831-Ben could be used as a suspension-additive for the preparation of suspensions containing 5% hexaconazole.

Effect of external high pressures on the clay mineral sodium montmorillonite intercalated with methylated octadecylammonium bromide surfactants

Raman microprobe spectra of the clay mineral Wyoming SWy-2-sodium montmorillonite intercalated with the surfactants, methyltrioctadecylammonium bromide (TOMA) dimethyldiotadecylammonium bromide (DODMA) and octadecyl-trimethylammonium bromide (ODTMA), have been measured in the CH2 stretching region at external pressures up to ∼40kbar with the aid of a diamond-anvil cell. In the case of the intercalated clays containing TOMA and DODMA, the Raman data afford evidence for gauche to trans conformational changes in the orientation of the CH2 chains in the surfactants with increasing pressure. These conformational changes are reversed completely upon the release of pressure.

J-aggregates of thiacyanine dye organized in LB films: Effect of irradiation of light

In the present communication we report the preparation and characterizations of Langmuir and Langmuir–Blodgett films of a thiacyanine dye N,N′-dioctadecyl thiacyanine perchlorate (NK) mixed with Octadecyl trimethyl ammonium bromide (OTAB). The relationship between the molar ratio of OTAB and NK and the orientation of molecules at the air–water interface was investigated using surface pressure-area per molecule ( π–A) isotherm. UV–vis absorption and fluorescence spectroscopic investigations reveal that prominent J-aggregation of NK molecule was observed in the LB films lifted at higher surface pressure. This J-aggregation can be controlled by diluting the NK molecules with OTAB. It was observed that the J-aggregates of NK decayed to monomer and H-aggregates when the NK-LB film was exposed to a monochromatic light of wavelength 460 nm ( λ max of J-aggregates).

Study on Determination of Trace Copper by Spectrophotometry after Flotation Separation Using Microcrystalline Adsorption System

AbstractThe paper presents a novel method for the flotation separation of Cu2+ using microcrystalline adsorption system prior to the determination by spectrophotometry. The effects of different parameters, such as the dosages of NH4SCN and octadecyl trimethyl ammonium bromide (OTMAB), various salts on the flotation yield of Cu2+ have been investigated to select the optimum experimental conditions. The possible flotation separation mechanism of Cu2+ was discussed. The results showed that under the optimum conditions, octadecyl trimethyl ammonium bromide cation (OTMAB+) reacted with SCN‐ to produce the microcrystalline matter (Ms‐M) of (OTMAB+·SCN‐), the water‐insoluble ternary association complex of [Cu(SCN)4] (OTMAB)2 which produced by Cu2+ and SCN‐, OTMAB+ was quantificationally adsorbed on the surface of Ms‐M of (OTMAB2+·SCN‐) and was floated above water phase, the liquid‐solid phases were formed with clear interface. In this condition, K+, Na+, Ca2+, Mg2+, Al3+, Fe2+, Mn2+, Ni2+, Cd2+ and Co2+ could not be floated. Therefore, Cu2+ was separated completely from the above metal ions. A new method of determination of trace copper by flotation separation was established. The proposed method has been successfully applied to the determination of Cu2+ in plating waster water, and the results agreed well with AAS method. The recoveries were 93.3%∼107.8%, and the RSD was 1.9%∼2.1%.

Effect of ion exchange treatment on the properties of muscovite filled epoxy composite

This paper reports the effect of ion exchange treatment of muscovite particles on the properties of muscovite filled epoxy composites. Ion exchange treatment was performed in order to improve the muscovite-epoxy interfacial adhesion and dispersion in the epoxy matrix. Fourier Transmission Infrared (FTIR) analysis showed that octadecyltrimethylammonium bromide (ODTMAB) was successfully exchanged with the potassium ion on muscovite. Determination of the mechanical properties of treated muscovite filled epoxy, over a range of muscovite loadings (10 wt.% to 40 wt.%), reveals that the flexural strength and fracture toughness values are superior to that of untreated muscovite epoxy composite. A micrograph of the flexural fracture surface was investigated in order to justify the dispersion of muscovite particles in the matrix.

Rheology of PVAc–MMT–STAB

Polyvinyl acetate (PVAc) is considered to be an acceptable environmental friendly adhesive, and montmorillonite (MMT) is a cheap and accessible natural nano-mineral. In this work, MMT was first organically activated by octadecyl trimethyl ammonium bromide (STAB). The intercalated nano-composite, MMT–STAB, was then polymerized with VAc. The influence of various additions of MMT–STAB on the rheology of PVAc–MMT–STAB was analysed using the power-law function equation and the Cross–Williamson model viscous equation. The results showed that MMT–STAB was able to improve the rheology of PVAc. The PVAc and PVAc–MMT–STAB all were pseudo-plastic non-Newtonian fluids, with a flow index (i) of 0.93. The apparent viscosity (η), fluid consistency (Ï), characteristic time of materials (ζ), zero shear viscosity (η 0), weight average molecular weight (M w), number average molecular weight ( M n) and the solid content (O), all increased with increasing additions of MMT–STAB as a result of the polymerization process. All properties, apart from ζ, showed a maximum with the addition of 2.0 wt%. The limiting viscosity (η ∞) was 0 mPa s for all samples of PVAc or PVAc–MMT–STAB. Their storage stability was found to be excellent. The reasonable addition of MMT–STAB in polymerization was found to be no more than 2.0 wt% of VAc. In addition, both PVAc and PVAc–MMT–STAB exhibited the normal stress effect (or Weissenberg effect), also known as the 'pole-climbing phenomenon'.

Orange II adsorption on palygorskites modified with alkyl trimethylammonium and dialkyl dimethylammonium bromide — An isothermal and kinetic study

We modified an Australian palygorskite with octadecyl trimethylammonium bromide (ODTMA) and dioctadecyl dimethylammonium bromide (DODMA) at different concentrations, and assessed these organo-palygorskites for adsorption of the anionic dye orange II. The surface and pore structure of the modified palygorskites were analysed by nitrogen adsorption. Orange II adsorption on palygorskites modified with DODMA and ODTMA quantity equivalent to twice the cation exchange capacity (CEC) of palygorskite was as high as 92 and 88mg/g at 25°C. The ODTMA and DODMA modified palygorskites did not differ greatly in their adsorption capacities. We also studied the influence of various experimental parameters such as the amount of adsorbent, mixing time, temperatures and pH values on the adsorption of orange II by the organo-palygorskites. Both electrostatic attraction as well as van der Waals interaction controlled the adsorption over the whole range of concentrations. This study demonstrates the potential application of organo-palygorskites for the remediation of anionic dyes from wastewater.

XRD Study of Hydrophlogopite Intercalated with Alkyl Quaternary Ammonium Salt

Hydrophlogopite was modified with sodium and then organically intercalated with a series of alkyl quaternary ammonium salts. The organically intercalated samples were characterized by X-ray diffraction analysis (XRD) and the effect of alkyl quaternary ammonium salt on the interlayer spacing of hydrophlogopite was discussed. The results showed that if the same alkyl quaternary ammonium salt was used to intercalate hydrophlogopite, the interlayer spacing of hydrophlogopite increased gradually with the rise of the added amount of quaternary ammonium salt, and that if different quaternary ammonium salts with the same amount were used, the interlayer spacing increased gradually with the rise of the chain length of the alkyl quaternary ammonium salts. For the alkyl quaternary ammonium salts with large chain length (n>10), the inflection point for the increasing interlayer spacing of the intercalated hydrophlogopite is at about 0.5 times of CEC. When octadecyl trimethyl ammonium bromide is used as intercalation agent and the added amount is 5 times of CEC, the interlayer spacing of hydrophlogopite is relatively maximal.

Uranium sorption on bentonite modified by octadecyltrimethylammonium bromide

The sorption of U(VI) on octadecyltrimethyl-bentonite was investigated at the pH values of the aqueous phase ranging from 3 to 10 and the concentrations of U(VI): 0.1–1mmol/dm3. The concentrations of alkylammonium cation in bentonite were increased from 21% to 150% of CEC (cation exchange capacity). It was determined that the sorption of U(VI) on modified bentonite, i.e. the distribution constant –Kd decreases with the percent of mineral modification until it attains a minimum at 76% of CEC and then increases again. The effective sorption of U(VI) was found to be in the pH range: 6–10 for the modified bentonite and was explained as the consequence of U(VI) anionic hydroxy complexes sorption.Both FT-IR and XRD spectra of the modified bentonite were analyzed and provided arguments for the existence of surfactant cations in the form of monolayer and bilayer in the interlamellar space of bentonite. In turn the luminescence spectra of bentonite suspensions, i.e. their character at different values of pH, proved the existence of hydroxide-like planar polymeric U(VI) species in the bentonite phase at pH 9.

Sorption of quaternary ammonium compounds in soils: Implications to the soil microbial activities

Despite their widespread use in household activities and various industries, information on the toxicity of quaternary ammonium compounds (QACs) to microbial activities in soil is scant. This study investigated the effect of three commonly used QACs namely hexadecyltrimethyl ammonium bromide (HDTMA), octadecyltrimethyl ammonium bromide (ODTMA) and Arquad on dehydrogenase and potential nitrification activities in three different soils. The toxicity of QACs on the dehydrogenase activity and potential nitrification in these soils followed the order: HDTMA>ODTMA>Arquad and Arquad>HDTMA>ODTMA, respectively. HDTMA, ODTMA and Arquad exhibited toxicity to dehydrogenase activity at concentration of 50, 100 and 750mgkg−1 soil, respectively, whereas potential nitrification was inhibited by HDTMA and ODTMA even at 50mgkg−1 soil. Arquad exhibited toxicity to potential nitrification at comparatively higher concentration of 250mgkg−1 soil, with the severity of toxicity very intense at higher concentrations. The nature of QACs and soil properties influenced the toxicity. The toxic effect of QACs on soil microbial activities was more influenced by the relative release of sorbed QACs in soils. This study provides valuable information on the toxicological properties of some widely used QACs on important soil microbial activity parameters. To our knowledge, this is the first report.

The adsorption of cationic surfactants on BN surface: Its effects on the thermal conductivity and mechanical properties of BN-epoxy composite

The adsorption of four cationic surfactants, dodecyltrimethylammonium bromide (DTAB), tetradecyltrimethylammonium bromide (TTAB), hexadecyltrimethylammonium bromide (HTAB), and octadecyltrimethyl ammonium bromide (OTAB), on boron nitride (BN) surface over the pH range of 5.5–8 was studied. The isoelectric point of BN was found at pH 4.3. The amount of surfactant adsorption was found to increase with the zeta potential of the surface and the surfactant chain length. The area occupied by the surfactant molecules also increased with increase in surfactant chain length. The results support the proposition that the surfactant molecule attached to the surface by having its headgroup attaching to the charged site on the surface and its tail projecting at an angle from the surface. The tail swung around in a right circular cone-shape space with the height of the cone varying with the surfactant chain length. The adsorption of the surfactant has changed the property of the BN surface from partial ionic to a hydrophobic surface with better wetting by the epoxy resin. This change has led to an increase in the thermal conductivity and mechanical properties of the surfactant-treated BN-epoxy composites.

Estimation of Cure and Thermal Degradation Kinetics of Epoxy/Organoclay Nanocomposite

Polymer nanocomposite was synthesized through the intercalation and exfoliation of organoclay in an epoxy matrix. The epoxy matrix was composed of diglycidyl ether of bisphenol A (DGEBA, epoxy base resin), 4,4'-methylene dianiline (MDA, curing agent) and malononitrile (MN, chain extender) and organoclay was prepared by treating the montmorillonite with octadecyltrimethylammonium bromide (ODTMA). The intercalation of the organoclay was estimated by wide angle X-ray diffraction (WAXD) and transmission electron microscope (TEM) analyses. In order to measure the cure rate of DGEBA/MDA (30 phr)/MN (5 phr)/Organoclay (5 phr), differential scanning calorimetry (DSC) analysis were performed at the heating rates of 5, 10, 15 and 20 oC/min, and the data was interpreted by Kissinger equation. Thermal degradation kinetics of the epoxy nanocomposite was also studied by thermogravimetric analysis (TGA). The epoxy sample was decomposed in the TGA furnace at the heating rates of 5, 10, 15 and 20 oC/min with nitrogen atmosphere of 50 ml/min. The TGA data was introduced to the Ozawa equation and the degradation activation energy was calculated according to the degradation ratio. The activation energy for cure kinetics was 43.3 kJ/mol and that for thermal degradation was 171.5 kJ/mol.

주기적인 메조포러스 유기실리카/고분자 복합재료 제조

Periodic mesoporous organosilicas (PMO) were synthesized using bis(triethoxy silyl) ethane (BTEE) as the precursor and dodecyl trimethyl ammonium bromide(DTMA), cetyl trimethyl ammonium bromide(CTMA), and octadecyl trimethyl ammonium bromide(ODTMA) as the templating agents. The surface area and pore volume of PMO decrease with the increasing of chain length of templating agents. However, the chain length of templating agents almost has no effect on the pore diameter of PMO. From the XRD and the DSC experiments, we found that the chain length of surfactants using as the templating agents has an effect on the melting transition of polyethylene. But it has no effect on the melting transition of poly(ethylene oxide). The results of TGA prove that the thermal decomposition temperature of polymer which was penetrated into PMO was increased.

Miscibility of anhydrous cationic surfactant mixtures

Inverse gas chromatography (IGC) has been used for studying the miscibility of anhydrous cationic surfactant mixtures. Dodecyltrimethylammonium bromide (C 12TAB), octadecyltrimethylammonium bromide (C 18TAB) and their mixtures have been used as stationary phases. In these types of stationary phases, the working temperature was determined by Differential Scanning Calorimetric (DSC) and Inverse Gas Chromatography (IGC) techniques. Values of the interaction parameters between the cationic surfactants obtained at four different compositions of their mixtures and at five temperatures showed that the miscibility depended on the composition and suggested that the interactions became more unfavorable with the increment of C 18TAB concentration in the mixtures. The results have been interpreted by comparing the structure of the anhydrous lamellar liquid crystals with that of the lamellar mesophases formed in aqueous solutions. Deviations of the systems from the parameter solubility model have been discussed in terms of the entropy contribution to the Flory-Huggins interaction parameter.

The Dynamin Inhibitors MiTMAB and OcTMAB Induce Cytokinesis Failure and Inhibit Cell Proliferation in Human Cancer Cells

The endocytic protein dynamin II (dynII) participates in cell cycle progression and has roles in centrosome cohesion and cytokinesis. We have described a series of small-molecule inhibitors of dynamin [myristyl trimethyl ammonium bromides (MiTMAB)] that competitively interfere with the ability of dynamin to bind phospholipids and prevent receptor-mediated endocytosis. We now report that dynII functions specifically during the abscission phase of cytokinesis and that MiTMABs exclusively block this step in the cell cycle. Cells treated with MiTMABs (MiTMAB and octadecyltrimethyl ammonium bromide) and dyn-depleted cells remain connected via an intracellular bridge for a prolonged period with an intact midbody ring before membrane regression and binucleate formation. MiTMABs are the first compounds reported to exclusively block cytokinesis without affecting progression through any other stage of the cell cycle. Thus, MiTMABs represent a new class of antimitotic compounds. We show that MiTMABs are potent inhibitors of cancer cell growth and have minimal effect on nontumorigenic fibroblast cells. Thus, MiTMABs have toxicity and antiproliferative properties that preferentially target cancer cells. This suggests that dynII may be a novel target for pharmacologic intervention for the treatment of cancer.

Adsorption of the herbicide 2,4-D on organo-palygorskite

Among the clay minerals, montmorillonite is the most extensively studied material using as adsorbents, but palygorskite and its organically modified products have been least explored for their potential use in contaminated water remediation. In this study, an Australian palygorskite was modified with cationic surfactants octadecyl trimethylammonium bromide and dioctadecyl dimethylammonium bromide at different doses. A full structural characterization of prepared organo-palygorskite by X-ray diffraction, infrared spectroscopy, surface analysis and thermogravimetric analysis was performed. The morphological changes of palygorskite before and after modification were recorded using scanning electron microscopy, which showed the surfactant molecules can attach on the surface of rod-like crystals and thus can weaken the interactions between palygorskite single crystals. Real surfactants loadings on organo-palygorskites were also calculated based on thermogravimetric analysis. 1 CEC, 2 CEC octadecyl trimethylammonium bromide modified palygorskites, 1 CEC and 2 CEC dioctadecyl dimethylammonium bromide modified palygorskites absorbed as much as 12 mg/g, 42 mg/g, 9 mg/g and 25 mg/g of 2,4-dichlorophenoxyacetic acid respectively. This study has shown a potential on organo-palygorskites for organic herbicide adsorption especially anionic ones from waste water. In addition, equilibration time effects and the Langmuir and Freundlich models fitting were also investigated in details.