Concept: Cocamidopropyl betaine
Dimeric quaternary alkylammonium salts possess a favourable surface and antimicrobial activity. In this paper we describe synthesis, spectroscopic analysis, surface and antimicrobial activity as well as biodegradability of polymethylene-α,ω-bis(N,N-dialkyl-N-deoxy-D-glucitolammonium iodides), a new group of dimeric quaternary ammonium salts. This new group of gemini surfactants can be produced from chemicals which come from renewable sources. The structure of products has been determined by the FTIR and (1)H and (13)C NMR spectroscopy. The biodegradability, surface activity and antimicrobial efficacy against Escherichia coli, Staphylococcus aureus, Candida albicans, Aspergillus niger and Penicillium chrysogenum were determined. The influence of the number of alkyl chains and their lengths on surface and antimicrobial properties has been shown. In general, dimeric quaternary alkyldeoxy-D-glucitolammonium salts with long alkyl substituents show favourable surface properties and an excellent antimicrobial activity.
The structure of solubilized water in water-in-n-heptane aggregates stabilized by mixtures of single- and double-tail quaternary ammonium surfactants, namely didodecyldimethylammonium chloride/dodecyltrimethylammonium chloride (DDAC/DTAC) or didodecyldimethylammonium bromide/dodecyltrimethylammonium bromide (DDAB/DTAB) was studied by two noninvasive techniques, (1)H NMR and FT-IR. In the former, the chemical shift data, δ(obs), were used to calculate the so-called deuterium/protium fractionation factor, φ(M), of the aggregate-solubilized water and were found to be unity. In the FT-IR study, upon increasing water/surfactant molar ratio, W, the frequency, ν(OD), of the HOD species decreases, while its full width at half height and its area increase. The results obtained from both techniques indicate that the water appears to be present as a single nano-phase and the structure varies continuously as a result of increasing W. In addition, the effect of changing the counter-ion (Br(-) or Cl(-)) on (1)H NMR and FT-IR results was investigated. In spite of the known difference in the dissociation of these counter-ions from micellar aggregates, this was found not to affect the state of solubilized water. This report gives further insight into the contradictory scientific debates on the structure of water in the polar nano-cores of microemulsions.
In this article we investigated effects of different types of conventional surfactants on exchange dynamics of quaternary ammonium dimeric surfactants, with chemical formula as C(14)H(29)N(+)(CH(3))(2)- (CH(2))(s)-N(+)(CH(3))(2)C(14)H(29)•2Br(-), short for 14-s-14. Two nonionic surfactants, TX-100 (TritonX-100) and Brij-35 [polyethylene glycol (23) laurylether], and one cationic surfactant, TTAB (n-tetradecyltrimethyl ammonium bromide), and one ionic surfactant, SDS (Sodium dodecyl sulfate) were chosen as typical conventional surfactants. Exchange rates of 14-s-14 (s=2, 3 and 4) between the micelle form and monomer in solution were detected by two NMR methods: one-dimensional (1D) line shape analysis and two dimensional (2D) exchange spectroscopy (EXSY). Results show that, the nonionic surfactants (TX-100 and Brij-35), the cationic surfactant (TTAB) and the ionic surfactant (SDS) respectively accelerated, barely influenced and slowed the exchange rate of 14-s-14. The effect mechanism was investigated by the self-diffusion experiment, relaxation time measurements (T(2)/T(1)), the fluorescence experiment (I(1)/I(3)) and the observed chemical shift variations. Results reveal that, nonionic conventional surfactants (TX-100 and Brij-35) loosened the molecule arrangement and decreased the hydrophobic interactions in the micelle, and thus accelerated the exchange rate of 14-s-14. The cationic conventional surfactant (TTAB) little changed the molecule arrangement and thus little influenced the exchange rate of 14-s-14. The ionic conventional surfactant (SDS) introduced the electrostatic attraction effect, tightened the molecule arrangement and increased the hydrophobic interactions in the micelle, and thus slowed down the exchange rate of 14-s-14. Besides, the two-stepwise exchange mechanism of 14-s-14 in the mixed solution was revealed through the interesting variation tendency of exchange rates of 14-s-14.
Microstructure of single chain quaternary ammonium cations intercalated into montmorillonite: a molecular dynamics study.
- Langmuir : the ACS journal of surfaces and colloids
- Published over 5 years ago
This study uses molecular dynamics (MD) modeling to examine the interlayer microstructures of montmorillonite intercalated with single chain QACs. Three types of QACs-tetramethylammonium (TMA), decyltrimethylammonium (DTMA), and hexadecyltrimethylammonium (HDTMA)-were selected to synthesize the organoclay complex, and the surfactant arrangement was analyzed quantitatively in systems in the absence of water. A series of arrangement patterns of interlayer QAC surfactant were observed, including lateral monolayers, lateral bilayers, pseudotrilayers, and paraffin monolayers, in agreement with previous experimental results. The effects of increasing one carbon chain length and amount of loading of QAC on the resultant QAC arrangement are summarized, yielding a model that provides insight into the prediction of synthesized QAC-clay microstructure and engineering behavior in practice.
- Langmuir : the ACS journal of surfaces and colloids
- Published about 5 years ago
Thermodynamically stable nanovesicular structures are of high interest for academia and industry in a wide variety of application fields, ranging from nanomaterials preparation to nanomedicine. Here we show the ability of quaternary ammonium surfactants and sterols to self-assemble forming stable amphiphilic bimolecular building-blocks with the appropriate structural characteristics to form, in aqueous phases, closed bilayers, named quatsomes, with outstanding stability with time and temperature. Molecular self-assembling of cholesterol (Chol) and surfactant cetyltrimethylammonium bromide (CTAB) was studied by quasi-elastic light scattering (QELS), cryogenic transmission electron microscopy (cryo-TEM), turbidity (optical density) measurements and molecular dynamic simulations (MD) with atomistic detail, upon varying the cholesterol-to-surfactant molar ratio. As pure species, CTAB forms micelles and insoluble cholesterol forms crystals in water. However, our molecular dynamic simulations reveal that the synergy between CTAB and cholesterol molecules makes them self-assemble into bimolecular amphiphiles and then into bilayers in the presence of water. These bilayers have the same structure of those formed by double tailed unimolecular amphiphiles.
Quaternary ammonium compounds are a large class of chemicals used for their antimicrobial and antistatic properties. Two common quaternary ammonium compounds, alkyldimethylbenzyl ammonium chloride (ADBAC) and didecyldimethyl ammonium chloride (DDAC), are combined in common cleaners and disinfectants. Introduction of a cleaner containing ADBAC+DDAC in the vivarium caused neural tube defects (NTDs) in mice and rats.
Viscosity Peak Due to Shape Transition from Wormlike into Disclike Micelles: Effect of Dodecanoic Acid
- Langmuir : the ACS journal of surfaces and colloids
- Published 2 months ago
Here, we have investigated the synergistic growth of long wormlike micelles and their transformation into disclike micelles, which occurs in three-component solutions composed of sodium lauryl ether sulfate (SLES; anionic), cocamidopropyl betaine (CAPB; zwitterionic), and dodecanoic acid (HC12; nonionic). The solution rheology is characterized in terms of zero-shear viscosities and characteristic times for micellar breaking and reptation. Furthermore, the microstructure evolution, leading to the observed rheological behavior, is revealed by cryo-TEM micrographs. In all cases, the CAPB-to-SLES ratio is fixed, while the fatty acid concentration is varied. At a certain HC12 concentration, the solution viscosity passes through a maximum. The cryo-TEM imaging indicates that wormlike micelles appear before the peak; grow further up to the peak; and finally transform into disclike aggregates (a very rare micellar structure) after the peak. The transformation of worms into discs leads to a drop in viscosity because the length-to-thickness aspect ratio of the discs is significantly lower than that of the worms. In this paper, we elucidate the structure-rheology relations in micellar solutions that might be applied for the design of personal-care and household formulations.
Working with and analysis of cationic surfactants can be problematic since aqueous concentrations are difficult to control, both when taking environmental aqueous samples as well as performing laboratory work with spiked concentrations. For a selection of 32 amine based cationic surfactants (including C8- to C18-alkylamines, C14-dialkyldimethylammonium, C8-tetraalkylammonium, benzalkonium and pyridinium compounds), the extraction from aqueous samples was studied in detail. Aqueous concentrations were determined using solid phase extraction (SPE; 3 mL/60 mg Oasis WCX-SPE cartridges) with recoveries of ≥80% for 30 compounds, and ≥90% for 16 compounds. Sorption to glassware was evaluated in 120 mL flasks, 40 mL vials and 1.5 mL autosampler vials, using 15 mM NaCl, where the glass binding of simple primary amines and quaternary ammonium compounds increased with alkyl chain length. Sorption to the outside of pipette tips (≤20% of total amount in solution) when sampling aqueous solutions may interfere with accurate measurements. Polyacrylate solid phase microextraction (PA-SPME) fibers with two coating thicknesses (7 and 35 μm) were tested as potential extraction devices. The uptake kinetics, pH-dependence and influence of ionic strength on sorption to PA fibers were studied. Changing medium from 100 mM Na+to 10 mM Ca2+decreases Kfwwith one order of magnitude. Results indicate that for PA-SPME neutral amines are absorbed rather than adsorbed, although the exact sorption mechanism remains to be elucidated. Further research remains necessary to establish a definitive applicability domain for PA-SPME. However, results indicate that alkyl chain lengths ≥14 carbon atoms and multiple alkyl chains become problematic. A calibration curve should always be measured together with the samples. In conclusion, it seems that for amine based surfactants PA-SPME does not provide the reliability and reproducibility necessary for precise sorption experiments, specifically for alkyl chain lengths beyond 12 carbon atoms.
Rheology-controlling agents are of importance for numerous products in a variety of industries. Replacement of synthetic chemicals with natural additives is desired in light of current environmental awareness and limited fossil resources. This study investigates the rheological features of Paenan, an exopolysaccharide produced by Paenibacillus polymyxa. Paenan exhibits highly shear-thinning flow behavior at concentrations ≥0.1% in 0.5% NaCl. Because of its pronounced intermolecular network, it forms stable, weak gels, thereby delivering elasticity as well as thixotropy. Application-relevant flow behavior is obtained with 60-65% less polymer as compared to the benchmark commercial products Xanthan and Gellan. In mixtures with surfactants (sodium lauryl ether sulfate, cetrimonium chloride, cocamidopropyl betaine, or lauryl glucoside), Paenan displays outstanding compatibility with every class of surfactant, making it superior to the partially incompatible Xanthan and Gellan. The weak-gel character of Paenan/surfactant systems is retained with three out of four surfactants, rendering Paenan highly interesting for various applications.
Agricultural researchers have always been pursuing synergistic technique for pest control. To evaluate the combined effects of quaternary ammonium compounds (QACs) and indoxacarb, their independent and joint toxicities to two insects, Spodoptera exigua and Agrotis ipsilon, and the aquatic organism, Daphnia magna, were determined. Results showed that all of five tested QACs increased the toxicity of indoxacarb to S. exigua and A. ipsilon. Both of benzyldimethyltetradecylammonium chloride (TDBAC) and benzododecinium chloride (DDBAC) exhibited significantly increased toxicities to S. exigua with synergic ratios of 11.59 and 6.55, while that to A. ipsilon were 2.60 and 3.45, respectively. When exposed to binary mixtures of QACs and indoxacarb, there was synergism on D. magna when using additive index and concentration addition methods, but only TDBAC, STAC and ODDAC showed synergistic effect in the equivalent curve method. The results indicate that the surfactants can be used as the synergists of indoxacarb in the control of Lepidoptera pests. However, their environmental risks should not be neglected owing to the high toxicity of all mixtures of indoxacarb and five QACs to D. magna.