Decylammonium Chloride Research Articles

Micellar and Surface Properties of Cationic-Cationic Binary Surfactant Mixtures: Synergistic Interactions and Solubility Enhancement of Anthracene

The micellar and surface behaviors of decylammonium chloride (DACl) in presence of L-alanine hydrochloride decylester (L-ADE) and L-alanine hydrochloride dodecylester (L-ADDE) at various mole fractions were investigated by conductivity and surface tension measurements. From the conductivity measurements, the critical micelle concentration (CMC), the degree of counter-ion ionization (α) and standard Gibbs energy of micellization (ΔG°mic) were investigated for both pure and binary mixtures. The molecular interaction parameter (β) and the micellar mole fraction (XmDACl) for mixed micelle formation by DACl/L-ADE (C10-C10) and DACl/L-ADDE (C10-C12) were calculated using the regular solution equation proposed by Rubingh. The ideal values of CMC (CMCideal) and the micellar mole fraction (XmDACl(ideal)) were also obtained for mixed micelle according to the pseudo phase theoretical models. The negative β values showed that there were synergistic interactions for all compositions of DACl/L-ADE and DACl/L-ADDE mixed systems. From the surface tension measurements, adsorption parameters such as the surface excess concentration (Γmax), minimum surface tension at the CMC, efficiency in the surface tension reduction (pC20), standard Gibbs energy of adsorption (ΔG°ads), and minimum area per head group of a molecule (Amin) in pure, mixed and their ideal values were also determined. The results indicated that the synergism and attractive interactions in the studied binary mixtures depend on the chain length of the cationic L-alanine ester and their mole fractions in the mixed system. The solubilization capacity of pure DACl and its mixed system with L-ADE and L-ADDE towards anthracene were determined and discussed in terms of molar solubilization ratio (MSR). Based on the MSR values, the solubility enhancement was found for anthracene in DACl/L-ADE and DACl/L-ADDE mixed systems.

Performance Test and Application Research of New Gemini Wetting Dust Suppressant

In order to solve the problem of low efficiency of dust-catching by water mist to the hard-to-wetting and respirable dust, a new wetting type dust suppressant of Gemini was proposed based on the analysis of the wetting effect of water mist. Based on the evaluation indexes of surface tension, contact Angle, wetting and settling rate of dust spray, the performance of polyquaternary ammonium salt AG-101, dodecanol polyoxyethylene etheryl dimethyl ammonium chloride, octyl alcohol polyoxyethylene etheryl dimethyl decyl ammonium chloride and macromolecular cationic PCD Gemini surfactants were optimized, and had carried on the dust-suppression performance in a certain open-pit iron mine field experiment research. The results show that the comprehensive dust suppression performance of mass concentration of 2.0% of quaternary ammonium salt polymer AG-101 is the best, indoor experimental tests showed the dust rate is 4.2 times the speed of water, the field test showed that the initial wetting speed is 4.4 times the speed of water, and the action time of dust and water mist suppression is shortened obviously. The field application proves that the total dust removal efficiency is 82.3% (water is 56.6%), which is 45.4% higher than that of water. The dust removal efficiency of respirable dust is 92.1%, which is 16.5% higher than that of water. The research results provide a new dust suppressing agent for optimization of mine spray dust removal.

A Combined Theoretical and Experimental Study of Solid Octyl and Decylammonium Chlorides and of Their Aqueous Solutions

The analysis of the thermal behavior of octyl- (OAC) and decylammonium chloride (DAC) has provided relevant new information. OAC shows a polymorphic phase transition that starts at 308 K and is completed at 313 K, between a monoclinic and a tetragonal structure, which belongs to a space group different from what was observed for other alkylammonium chlorides. At the melting temperature (463 K), the growing of a strong first sharp diffraction peak (FSDP) occurring at a d-spacing of ca. 21.0 Å was observed. DAC is characterized by two phase transitions at 318 (T(d1)) and 323 K (T(d2)). At T(d1), the LT polymorph coexists with a new-formed phase. At T(d2) the LT polymorph is replaced by a further polymorphic modification of DAC that becomes the only one at 328 K. This second phase transition signals the occurrence of a phase, closely related to the LT polymorph of HeAC, that crystallizes in the tetragonal crystal system a = ca. 5.00 Å and c = ca. 28.5 Å, P4/nmm space group. DAC melting starts at 458 K and is accompanied, as in the case of OAC, by the growing of a strong FSDP at a d-spacing of ca. 24.8 Å. A parallel DSC study confirmed the above-mentioned transitions. In addition, the structural properties of OAC/water and DAC/water mixtures were studied using an integrated approach, which combines X-ray diffraction and molecular dynamics (MD) techniques. A very good agreement between theoretical and experimental diffraction patterns has been obtained for both investigated mixtures. A thorough analysis of the MD trajectories shows that strong anion-water interactions are present in the mixtures, where Cl(-) forms a rather unstructured first hydration shell of water molecules bound to the anion in a linear Cl···H-O configuration. Moreover, cations and anions were found to interact with each other, and to form "solvent-shared ion pairs", in which one or more water molecules are shared between Cl(-) and the alkylammonium cation.

Determining micelle dimensions and shape in micellar surfactant solutions on the basis of the dispersion of the nuclear spin-lattice relaxation rate

The experimental and computed dispersion curves of the spin-lattice relaxation of systems containing asymmetric micelles are compared. The parameters of the structure of symmetric micelles are determined for aqueous solutions of sodium dodecylsulfate and decyl ammonium chloride on the basis of the obtained results.

Investigation of gas/liquid interface of small bubbles formed in solutions of different alkylammonium chlorides

The electrophoretic mobility of nitrogen gas bubbles was measured in solutions of different n-alkylammonium chlorides in a cylindrical cell, 30 mm in diameter and 70 mm in length, rotating in order to keep the bubbles on a line of the rotation axis of the cylinder. An electric charge field was applied to the solutions through two electrodes located at both ends of the cylinder. The mobility was measured as a function of the size of bubbles. The maximum mobility U *(= v/ E) and the corresponding diameter of the bubble, d b * were used to determine the apparent surface charge density, σ at the gas/liquid interface. The surface charge density of bubbles was found (i) to be negative even in solutions of all n-alkylammonium chlorides carbon atoms, the number n of which was selected to be n = 1, 2, 3, and 10, and (ii) to decrease in magnitude with increasing number of carbon atoms. Decylammonium chloride (DAC; n = 10) is a typical cationic surfactant, however, the surface was revealed to still be negative, which strongly suggests that DAC molecules do not always come out to the gas/liquid interface. The change in surface charge density with the added salt concentration was analyzed, and as a result, it was found that only DAC follows the Langmuir adsorption isotherm.

Photophysical and photochemical studies of chlorophyll a and cobalt(II)tetraphenylporphyrin in poly( l-glutamate)-decylammonium ion complex

Spectroscopic studies were carried out on chlorophyll a and cobalt(II)tetraphenylporphyrin solubilized in a poly( l-glutamate) (Poly(Glu))-decylammonium chloride (DeAC) complex system, in the presence of methylviologen (MV 2+). The cooperative binding occurred between the anionic Poly(Glu) and the cationic DeAC, leading to the formation of micelle-like hydrophobic clusters of DeAC and also the change in conformation of the Poly(Glu) from the random coil to the α-helix. All of the absorption spectra, the fluorescence quantum yields and the fluorescence lifetimes indicated the existence of equilibrium between the aggregated biofunctional molecules in the bulk phase and the monomeric species in the complex phase of the Poly(Glu)–DeAC solution. The fluorescence quenching of the biofunctional molecules by methylviologen indicates that the conformation-dependent electron transfer occurs in the complex phase.

Adsorption and micelle formation of alkylammonium chloride–alkyltrimethylammonium chloride mixtures

The surface tension of the aqueous solutions of binary cationic surfactant mixtures of (1) dodecylammnonium chloride (DAC)–tetradecyltrimethylammonium chloride (TTAC), (2) decylammonium chloride (DeAC)–dodecyltrimethylammonium chloride (DTAC), and (3) DAC–DTAC was measured as a function of the total molality and composition of surfactants at 298.15 K. The compositions of surfactants in the adsorbed film and micelle were evaluated and the phase diagram of adsorption and that of micelle formation were constructed. Furthermore the excess Gibbs energies of adsorption and micelle formation were calculated to estimate the deviation from the corresponding ideal mixing. It was found that the surface and micelle are enriched in trimethylammonium salts in (1) and (2), while in ammonium salt in (3) compared to the bulk solution. On the other hand, the micelle is enriched in trimethylammonium salts compared to the surface at the critical micelle concentration (CMC) in all the systems. The miscibility of the surfactants was clarified from the standpoints of the structure of the head group and of the matching between the size of polar head group of surfactants and the difference in hydrocarbon chain length.

Conformation-dependent photoinduced hydrogen evolution with Co(II)tetraphenylporphyrin–poly( l-glutamate) complex

Hydrogen production was performed under visible-light and combined UV/visible-light irradiation by using a system consisting of cobalt(II)tetraphenylporphyrin (CoTPP), methylviologen (MV 2+), ethylenediaminetetraacetic acid disodium salt and Pt-loaded poly( l-glutamate) (Poly(Glu)) in aqueous decylammonium chloride (DeAC) solution. CoTPP was solubilized in hydrophobic clusters of DeAC induced by its cooperative binding to Poly(Glu). About 0.15 and 3.5 μmol of hydrogen gas were obtained after irradiation for 3 h using visible-light and combined UV/visible-light, respectively. The rate of hydrogen evolution depended on the change in the conformation of Poly(Glu) induced by the cooperative binding with DeAC. An electron was transferred from CoTPP to MV 2+ in the Poly(Glu)–DeAC complex system via the singlet state, finally resulting in the hydrogen evolution.

Visible-light induced hydrogen production using a polypeptide–chlorophyll complex with α-helix conformation

Hydrogen production was accomplished under visible-light irradiation by using a system consisting of a biomolecule (chlorophyll a), methylviologen, ethylenediaminetetraacetic acid disodium salt and Pt-loaded poly(l-glutamate) (Poly(Glu)), in aqueous decylammonium chloride (DeAC) solution. Spectroscopic studies revealed that chlorophyll a is solubilized in the hydrophobic clusters of Pt-loaded Poly(Glu)-decylammonium chloride. In the Poly(Glu)-DeAC complex, the electron transfer occurred between chlorophyll a and methylviologen leading to hydrogen production. The most noticeable result is that the rate of hydrogen evolution depends on the change from the random coil to the alpha-helix in conformation of Poly(Glu) induced by the cooperative binding with DeAC.

Conformation-dependent hydrogen evolution with cobalt(II)tetraphenylporphyrin solubilized into poly( l-glutamate)–decylammonium ion complex

Hydrogen production was performed under visible light irradiation by using a system consisting of cobalt(II)tetraphenylporphyrin, methylviologen, ethylenediaminetetraacetic acid disodium salt and Pt-loaded poly( l-glutamate) (Poly(Glu)) in aqueous decylammonium chloride (DeAC) solution. The rate of hydrogen evolution depended on the change in the conformation of Poly(Glu) induced by the cooperative binding with DeAC.

Headgroup Motion in a Lyotropic Lamellar Phase by Deuterium and Nitrogen-14 Relaxation Studies

Deuterium (2H) and nitrogen-14 (14N) NMR spectroscopy were used to investigate the molecular dynamics of a lyotropic liquid crystal. Deuterium spectral densities of motion for the C1 deuterated site on the chain of the molecule decylammonium chloride (DACl) at the Larmor frequency 61.4 MHz and those for the (14)N at the headgroup (NH(3)(+)) at 28.9 MHz are analyzed quantitatively in the lamellar phase of the DACl-d(11)/water binary system to shed light on the headgroup dynamics. The motional model used is the small step rotational diffusion for reorientations plus internal rotations of the methylene group in the strong collision limit. The tumbling motion of the long axis of the DACl molecule in the aggregates seems to be as rigorous as the molecular spinning motion, likely due to the proposed motional model. The similarity of deuterium spectral densities from the C1 and C2/C3 sites may indicate a relatively rigid unit of C1-C2-C3 in the backbone.

Influence of Lyotropic Liquid Crystals on the Ability of Antibodies To Bind to Surface-Immobilized Antigens

We report an experimental study of the influence of lyotropic liquid crystalline phases on the ability of antibodies to bind to protein antigens immobilized on surfaces when the antibodies are delivered and bind to the antigens from the lyotropic liquid crystals (LCs). The LCs were prepared from anionic amphiphiles (sodium decyl sulfate (SDeS), cesium pentadecafluorooctanoate (CsPFO), and potassium laurate (KL)), cationic amphiphiles (decylammonium chloride (DACl) and cetylpyridinium chloride (CPCl)), nonionic amphiphiles (Brij 30 and Triton X114), and the zwitterionic surfactant tetradecyldimethyl-amineoxide (C14AO). In addition, we investigated LCs prepared from the nonamphiphilic molecules disodium cromoglycate (DSCG) and the dye molecule Direct Blue 67. Antihuman IgGs conjugated with the fluorescent label fluorescein-isothiocyanate (FITC) were dissolved in 12 lyotropic LCs and then incubated with human IgG that was arrayed on surfaces. Fluoresence microscopy was used to image antihuman IgG that bound to the immobilized human IgG. From this survey of lyotropic LCs, we identified three LCs (DSCG, C14AO, and CPCL) that permitted antihuman IgG dissolved in the LC to recognize and bind to surface-bound human IgG. Antibody binding in the other LCs was prevented by a number of mechanisms, including denaturation of the IgG (anionic surfactants) as well as slow mass transport due to high viscosity of the LC phases (nonionic surfactants). Because the lyotropic LC formed from DSCG exhibited the highest birefringence and the lowest viscosity among the LCs formed from DSCG, C14AO, and CPCL, the binding of antibodies in DSCG-based LCs to virus-infected cells was also investigated. We found that the binding of antibodies to vesicular stomatitis virus (VSV) that was inoculated into human epitheloid cervical carcinoma cells was highly specific in the lyotropic LC prepared from DSCG.

Collective and local molecular dynamics in the lyotropic mesophases of decylammonium chloride:H1andH2NMR study

The collective and individual dynamics of decylammonium chloride (DACl) molecules in water environment were investigated as a function of surfactant concentration and temperature. In the presence of water the DACl forms a variety of self-assembled structures, ranging from isotropic micellar systems to lyotropic liquid crystalline phases of hexagonal, nematic, and lamellar types. In order to characterize the complex molecular dynamics that occur in the DACl-water system, we applied 1H and 2H NMR techniques that cover the whole frequency range between 1 kHz and 30 MHz. The slow molecular dynamics were studied by 1H NMR fast-field-cycling T1 measurements and pulse-frequency dependence of 2H NMR transverse relaxation time, performed by means of the Carr-Purcell-Meiboom-Gill sequence. We detected a well-expressed contribution of order director fluctuations, i.e., layer undulations, with characteristic omega(-1)(L) frequency dependence of T(-1)(1) in the lamellar phase. Its presence indicates a relatively weak impact of interactions between neighboring DACl layers. The frequency dependence of proton T(-1)(1) in the hexagonal phase exhibits a different type of frequency dispersion, T(-1)(1) approximately omega(-1.32)(L). The increase in the exponent is explained with the quasi-one-dimensional character of fluctuations in elongated cylinders. Further, the T1 and T2 relaxation times of deuterons selectively attached to the C2 and C7 segments of the hydrocarbon chains of DACl were measured at a Larmor frequency of 30.7 MHz, providing quantitative information about local molecular dynamics.

Synthesis and Conformational Transition of Surface-Tethered Polypeptide: Poly(l-glutamic acid)

Surface-grafted poly(l-glutamic acid) (PLGA) films on silicon oxide surfaces were prepared and examined for their responsiveness to the external stimuli of pH, surfactant (decylammonium chloride), and divalent metal ion (Ca2+) in aqueous solutions. A surface-initiated vapor deposition−polymerization of N-carboxyanhydride of γ-benzyl l-glutamate was first performed to synthesize surface-grafted poly(γ-benzyl l-glutamate) (PBLG) thin films, followed by debenzylating with hydrogen bromide in anhydrous benzene. The successful conversion of surface-grafted PBLG to PLGA films was confirmed by Fourier transform infrared spectroscopy and ellipsometry. The conformational transitions and the corresponding changes in film thicknesses and refractive indices were in situ examined by circular dichroism (CD) and ellipsometry, respectively. The CD study shows that the conformation undergoes a transition between α-helix and random coil at pH 5.75−7. Upon the conformational transition, the film thicknesses and refractive i...

Deuterium NMR study of chain configurational transitions in decylammonium chloride

Chain configurational transitions have been studied in a selectively deuterated model membrane compound, decylammonium chloride, by means of deuterium NMR spectroscopy. The segmental order parameters of the chain near the head group and near its end are determined as a function of temperatures in the i, δ and α phases. There is no evidence of the nematic order parameter showing critical behaviour at the i–δ phase transition. The tilt angle of the decylammonium chain with respect to the normal of the chlorine layers has been determined as a function of temperature in the δ phase.

Critical chain dynamics near the interdigitated–noninterdigitated chain configurational phase transition in decylammonium chloride

We have carried out a H1 nuclear magnetic resonance line shape analysis near the irreversible interdigitated-to-noninterdigitated chain configurational phase transition in decylammonium chloride (C10H21NH3Cl), a model biomembrane. The splitting parameter corresponding to the nematic order of the hydrocarbon chain shows a two-dimensional Ising behavior and indicates a chain defect motion in addition to the chain reorientational motion. The origin of the low-frequency critical fluctuation is attributed to a critical slowing down of the collective gear-like reorientation of the rigid hydrocarbon chain.

The Effect of Water on the Flow Orientation Process of Lyotropic Liquid Crystals Cholesterized by D(+)-Mannose

The rheological behavior of cholesteric lyotropic liquid crystals can give information about the chiral forces involved in the formation of the cholesteric arrangement. In the present work, we studied the effect of water availability on the orientation process of a lyotropic liquid crystal system submitted to flow. Different mesophases based on decylammonium chloride were prepared with different amounts of D(+)-mannose added as inductor. It was observed that the flow orientation process on cholesteric lyomesophases is different when occurring in a room atmosphere or a water-saturated atmosphere. For samples sheared in a room atmosphere, the orientation process involves an initial step of destruction of the cholesteric structure caused by shear, leading to the formation of microdomains with different orientations. In a second stage these microdomains orient themselves, forming a new helical structure in the flow direction. When the systems are sheared in a water-saturated atmosphere, the orientation process involves the accommodation of micelles into a new structure seeking the best orientation in the flow direction.

The Influence of Water on the Orientation Process of Cholesteric Lyotropic Liquid Crystals

The rheological behavior of cholesteric lyotropic liquid crystals can give information about the chiral forces involved in the formation of the cholesteric arrangement. In the present work, we studied the effect of water availability on the orientation process of a lyotropic liquid crystal system submitted to flow. We prepared different mesophases based on decylammonium chloride with different amounts of cholesterol added as an inductor. It was observed that the orientation process should involve an initial step of destruction of a cholesteric structure caused by shear that leads to the formation of microdomains. In a second stage these microdomains will orientate themselves, forming a new helical structure in the direction of the flow. Finally, on the third stage, the accommodation of the micelles on a new structure, seeking the best orientation of the system on the flow direction, could be observed. The obtained results showed that the content of water available would determine the existence of fragmentation, rearrange, and accommodation stages.

Low-Frequency Chain Dynamics in Decylammonium Chloride

Proton nuclear magnetic resonance (NMR) relaxation measurements were carried out to investigate the low-frequency hydrocarbon chain dynamics in decylammonium chloride (C 10 H 21 NH 3 Cl), a model biomembrane undergoing an irreversible structural phase transition. It is demonstrated by systematic proton NMR study of spin-spin relaxation and rotating frame spin-lattice relaxation that a low-frequency chain dynamics is responsible for the critical dynamics associated only with the interdigitated-to-noninterdigitated chain configurational phase transition.

Low-frequency collective chain dynamics in a model biomembrane

Proton NMR was employed as a probe for the collective hydrocarbon chain dynamics in decylammonium chloride (C10H21NH3Cl), a model biomembrane undergoing an irreversible structural phase transition sequence. Our rotating frame spin-lattice relaxation measurements revealed a low-frequency critical collective chain dynamics in the kHz regime, which is associated with the interdigitated to noninterdigitated chain configurational phase transition.