Synthesis and Surface Active Properties of tri[(N‐alkyl‐N‐ethyl‐N‐Sodium carboxymethyl)‐2‐Ammonium bromide ethylene] Amines

Trimeric betaine surfactants tri[(N‐alkyl‐N‐ethyl‐N‐sodium carboxymethyl)‐2‐ammonium bromide ethylene] amines were prepared with raw materials containing tris(2‐aminoethyl) amine, alkyloyl chloride, lithium aluminium hydride, sodium chloroacetate, and bromoethane by alkylation, Hoffman degradation reaction, carboxymethylation and quaternary amination reaction. The chemical structures of the prepared compounds were confirmed by FTIR, ¹H NMR, MS and elemental analysis. With the increasing length of the carbon chain, the values of their critical micelle concentration initially decreased. Surface active properties of these compounds were superior to general carboxylate surfactants C₁₀H₂₁CHN⁺(CH₃)₂COONa. The minimum cross‐sectional area per surfactant molecule (A_min), standard Gibbs free energy adsorption (ΔG_ads) and standard Gibbs free energy micellization (ΔG_mic) are notably influenced by the chain length n, and the trimeric betaine surfactants have greater ability to adsorb at the air/water interface than form micelles in solution. The efficiency of adsorption at the water/air interface (pC₂₀) of these surfactants increased with the increasing length of the alkyl chain. Their foaming properties, wetting ability of a felt chip, and lime‐soap dispersing ability were also investigated.     

Interaction Between Cationic and Anionic Surfactants: Detergency and Foaming Properties of Mixed Systems

The micellar and interfacial behavior of mixtures of the anionic surfactant (alcohol ether sulfate, AES) with quaternary ammonium type cationic surfactants dodecyltrimethyl ammonium chloride (DTAC), dodecyl-(2-hydroxyethyl)-dimethyl ammonium chloride (DHDAC), dodecyl-di(2-hydroxyethyl)-methyl ammonium chloride (DHHAC) were investigated by means of surface tension measurements. Various physicochemical properties such as surface activity parameters (CMC, γ _CMC, Г _max, A _min), the micellar and interfacial compositions (x ₁ ^m , x ₁ ^σ ), interaction parameters (β ^m , β ^σ ), and activity coefficients ( \(f_{1}^{m}\) , \(f_{2}^{m}\) , \(f_{1}^{\sigma }\) , \(f_{2}^{\sigma }\) ) were evaluated. The influence of the hydroxyethyl groups of cationic surfactant component on the physicochemical properties of mixed systems has been analyzed. It is observed that the CMC values of the three mixed systems decrease with increases in the number of hydroxyethyl groups of the cationic surfactant component. From the results of β ^σ and β ^m values, the interactions between molecules for the three surfactant mixtures at the air/liquid interface increase in the following order DHHAC/AES < DHDAC/AES < DTAC/AES, but it is the opposite for the interactions in mixed micelles. The detergency and foaming properties of mixed systems were also studied. As expected, complex surfactant systems exhibit good detergency and foaming properties.     

Synthesis and Properties of Organosilicon Quaternary Salts Surfactants

Diethyl-benzyl-[3-methyldimethoxyl)]silpropyl ammonium chloride (DEBSAC) was synthesized from N,N-diethyl-aminopropyl-methyldimethoxysilane (DEAPMDES) and benzyl chloride. Diethyl-2,3-epoxypropyl-[3-methyldimethoxyl)] silpropyl ammonium chloride (DEEPSAC) was synthesized from DEAPMDES and epoxy chloropropane. Trimethyl-[3-methyldimethoxyl)] silpropyl ammonium chloride (TMSAC) was synthesized from trimethylamine and γ-chloropropylmethyldimethoxysilane (CPMDMS). The products were characterized by ¹H NMR, ¹³C NMR, and IR. The surface tension measurements showed that the organosilicon quaternary salts exhibit a lower surface tension and a lower critical micelle concentration (CMC) than the hydrocarbon counterparts. The plate count method experiments illustrated that DEEPSAC has a better degree of antibacterial activity against Escherichia coli than DEBSAC. The solubilizing effects of the organosilicon quaternary salts on organosilicone were studied by pseudo-ternary phase diagrams of synthesized products/cosurfactant(n-butanol)/water/octamethylcyclotetrasiloxane. The solubilizing activities decreased in the order of TMSAC > DEBSAC > DEEPSAC.     

Synthesis of switchable amphipathic molecules triggered by CO2 through carbonyl‐amine condensation

Five long‐chain alkyl amidines were synthesized by condensation of N,N‐dimethylacetamide with octylamine, decylamine, dodecylamine, tetradecylamine, and hexadecylamine, respectively. Synthesis conditions including solvent, pH, temperature, and ratio of reactants were studied. The series of long‐chain alkyl amidine compounds reacted with dry ice to produce amidinium bicarbonates cationic amphipathic molecules. The critical micelle concentration (cmc) and surface tension at cmc (γ_cmc) measured by drop volume method show that these amphipathic molecules have excellent surface activity. The changes of cationic content measured by two‐phase titration and conductivity before and after bubbling CO₂, show different properties between amidines and amidinium bicarbonates cationic amphipathic molecules. The switchable function of the amidinium bicarbonate cationic amphipathic molecule in emulsification and demulsification was studied. Practical applications : Our innovative work is synthesizing switchable amphipathic molecules, N′‐alkyl‐N,N‐dimethylacetamidines, by carbonyl‐amine condensation. Compared with a former way of synthesis, our work shows great potential advantages in industrial application. Our synthesis route is simpler with higher yield and is carried out at ambient temperature. Moreover, the products are environmentally friendly. Compared with traditional amphipathic molecules, our products, N′‐alkyl‐N,N‐dimethylacetamidines, show good switchable properties, which can be switched on and off, trigged by CO₂.This means these products can be reused for several times, which is significant for environmental protection.     

Antibacterial materials: structure–bioactivity relationship of epoxy–amine resins containing quaternary ammonium compounds covalently attached

Bifunctional aminoalkyldimethylpropylammonium salts (N‐(3‐aminopropyl)‐N,N‐dimethylpentylammonium chloride, N‐(3‐aminopropyl)‐N,N‐dimethyloctylammonium chloride, N‐(3‐aminopropyl)‐N,N‐dimethyldecylammonium chloride, N‐(3‐aminopropyl)‐N,N‐dimethyldodecylammonium chloride) are synthesized and their structure‐dependent antibacterial effect against Gram‐negative Escherichia coli and Gram‐positive Lactococcus lactis is investigated. To this end, resins prepared from bisphenol A diglycidyl ether (2,2‐bis[4‐(glycidyloxy)phenyl]propane) and diethylenetriamine (2,2′‐diaminodiethylamine) as matrix and the bifunctional aminoalkyldimethylpropylammonium salts in a ratio of 6 mol% compared to epoxy components are used. A dependence of antibacterial effect on alkyl chain length of the quaternary ammonium compounds is observed for both species. Furthermore, resins with N‐(3‐aminopropyl)‐N,N‐dimethyldecylammonium chloride in varying concentrations up to 16 mol% for both organisms show a concentration‐dependent antibacterial effect of the quaternary ammonium salt. The antibacterial materials are characterized by differential scanning calorimetry, infrared spectroscopy and rheological studies. © 2013 Society of Chemical Industry     

Synthesis of Sulfobetaine-Type Zwitterionic Gemini Surfactants (EAPMAC) and Their Oilfield Application Properties

Four sulfobetaine-type zwitterionic gemini surfactants bis{[(N-ethyl-N alkylamide-ethyl-N-(2-hydr oxyl-3-sodium sulfonic acid) propyl] methylene} ammonium chlorides (EAPMAC-11, EAPMAC-13 EAPMAC-15, and EAPMAC-17) were synthesized by three steps using triethylene tetramine, fatty-acid methyl esters, ethyl chloride, N,N′-dimethyl ethylenediamine, and 3-chloro-2-hydroxypropane sulfonic acid sodium as main raw materials. Their chemical structure was confirmed using Fourier transform infrared spectroscopy (FTIR), 1H-Nuclear Magnetic Resonance (¹H NMR), and elemental analysis. The surface activity, critical micelle concentration, and interfacial activity were correlated with the length of the carbon chain. The results show low emulsifying tendency toward crude oil, low interfical tension, high salt tolerance, and excellent long-term thermal stability. Moreover, high biocidal activities and good protection of metal surfaces against acidic environments are also reflected. These properties suggest that these new gemini surfactants have enormous application potential in oilfield application areas.     

A Novel Alkyl Sulphobetaine Gemini Surfactant Based on S‐triazine: Synthesis and Properties

A series of alkyl sulphobetaine Gemini surfactants C_n‐GSBS (n = 8, 10, 12, 14, 16) was synthesized, using aliphatic amine, cyanuric chloride, ethylenediamine, N,N′‐dimethyl‐1,3‐propyldiamine and sodium 2‐chloroethane sulfonate as main raw materials. The chemical structures were confirmed by FT‐IR, ¹H NMR and elemental analysis. The Krafft points differ markedly with different carbon chain length, for C₈‐GSBS, C₁₀‐GSBS and C₁₂‐GSBS are considered to be below 0 °C and C₁₄‐GSBS, C₁₆‐GSBS are higher than 0 °C but lower than room temperature. Surface‐active properties were studied by surface tension and electrical conductivity. Critical micelle concentrations were much lower than dodecyl sulphobetaine (BS‐12) and decreased with increasing length of the carbon chain from 8 to 16, and can reach a minimum as low as 5 × 10^?5 mol L^?1 for C₁₆‐GSBS. Effects of carbon chain length and concentration of C_n‐GSBS on crude oil emulsion stability were also investigated and discussed.     

Synthesis and Characterization of a Novel Series of Cationic Fumaric Polymerizable Emulsifiers

A series of novel cationic fumaric polymerizable emulsifiers (named as F series emulsifiers) were synthesized. The chemical structures of these emulsifiers were confirmed by ¹H NMR and MS and their minimal inhibitory concentrations to Escherichia coli were determined. Antibacterial tests of latex films showed that [2-(N-benzyl-N,N-dimethylamino)ethyl]dodecyl fumaric ammonium bromide, [2-(N-benzyl-N,N-dimethylamino)ethyl]decyl fumaric ammonium chloride and [2-(N-benzyl-N,N-dimethylamino)ethyl]dodecyl fumaric ammonium chloride can possibly be used as a polymerizable bactericides.     

Synthesis and Evaluation of New Anionic Gemini Dispersants as Oil Dispersants to Treat Crude Oil Spill Pollution

Floating petroleum oil spills on the marine ecosystem are generally associated with an escalation of serious environmental problems. This research aimed to synthesis five water-soluble anionic Gemini dispersants to minimize the effect of floating petroleum oil spills on the marine ecosystem. Referring to the spacer type, these dispersant are classified into two categories: the first category is the three acyl amine Gemini dispersants of N,N′- diacyl, (distearoyl-, dipalmitoy-, and dimyristoyl-) N,N-′ sodium 2-hydroxy 3-propane sulfonate propane 1,3 diamine, denoted S, P, and M, and the second category is two alkyl amine Gemini dispersants of N,N′dialkyl -(dicetyl-, and dilauryl-) N,N′-sodium 2-hydroxy 3-propane sulfonate propane 1,3 diamine, denoted C and L. Fourier transform infrared and ¹H NMR spectroscopy, gel permeation chromatography, and elemental analysis were used to verify the chemical formula of the synthesized dispersants. The effectiveness of the synthesized dispersants was investigated as regards their dynamic interfacial tension, carbon–chain length, and hydrophilic–lipophilic balance. The dispersion efficiency of the synthesized dispersant was detected qualitatively and quantitatively using the screen test and Warren Spring Laboratory methods, respectively. Experimental outcomes showed that the maximum dispersion efficiency of 94.7 wt% was achieved by dispersant C at a dispersant\oil ratio of 1:20 at 25°C.     

Synthesis and Surface-Active Properties of a Homologous Series of Star-Like Triple-Chain Anionic Surfactants Derived from 1,1,1-Tris(hydroxymethyl)ethane

A novel homologous series of trimeric anionic surfactants, 3C_nTE3CNa (where n is a fatty acid chain length of 7, 10, or 12), with three hydrocarbon chains and three carboxylate heads connected via tri‐etheric bonds were synthesized from long‐chain α‐bromo fatty acids and a triol, 1,1,1‐tris(hydroxymethyl)ethane. The obtained trimeric carboxylic acids were esterified and purified by silica gel column chromatography, then hydrolyzed with dilute sodium hydroxide solution to form a series of trimeric carboxylate surfactant products. All prepared compounds were analyzed by IR, ¹H NMR, and ¹³C NMR spectroscopy to confirm their chemical structures. Their surface‐active properties were investigated. The critical micelle concentrations (cmc) of 3C_nTE3CNa were in the range of 0.12–0.71 mmol/L, and the surface tensions at the cmc (γ_cmc) were 29.3–34.8 mN/m.     

Effect of the Alkyl Chain Length in N,N‐Dialkylpyridine‐3‐carboxamides upon their Extraction of Copper(II) from Aqueous Chloride Solutions

Abstract

Three nicotinamide derivatives with two butyl, hexyl, or octyl alkyl chains at amide nitrogen were synthesized. These model individual compounds were used for copper(II) extraction from acidic chloride solutions at constant ionic strength I = 1.0. It was found that during the extraction N,N‐dialkylpyridine‐3‐carboxamides form two complexes with copper(II) and chloride ions; these can transfer into the organic phase. In these complexes the molar ratio of copper:chlorine:extractant = 1:2:2 or 1:2:3. The obtained stability constants of N,N‐dihexyl‐ and N,N‐dioctylpyridine‐3‐carboxamides complexes with copper(II) chloride in water are comparable, but N,N‐dibutylpyridine‐3‐carboxamide complexes stability constants are significantly lower. The partition constants of these complexes in toluene–water system depend on amide hydrophobicity, increasing with increasing carbon chain length in N,N‐dialkylpyridine‐3‐carboxamides.     

Understanding specific effects on the standard potential shifts of electrogenerated species in 1-butyl-3-methylimidazolium ionic liquids

It has been established that the dependence of the E° values in function of the electrochemical media selected for a large amount of reversible redox probes in reduction and also in oxidation. For such a purpose several electroactive substances either in reduction (4-nitrotoluene, 1,3-dinitrobenzene, tetrakis(dimethylamino)ethylene, 1,3,5-trinitrobenzene, and 2,4,6-trinitroanisole) or oxidation (ferrocene, tetrathiofulvalene, tris-4-bromophenylamine, tris-4-tolylamine, and N,N,N′,N′-tetramethyl-para-phenylenediamine) have been studied in aprotic RTILs based on unsymmetrical organic cations (quaternary ammonium cations, such as 1-butyl-3-methyl imidazolium) and a weakly coordinating inorganic anion (anions with low Lewis basicities, e.g., BF₄, PF₆). Ion-pairing effects between imidazolium ions and anions and dianions for the electrochemically generated species, the solvation differences between BF₄⁻/PF₆⁻ cations and dications as well as some different reaction mechanism pathways followed by these electrogenerated species in function of the solvent have also been carefully examined.     

Preparation,Characterization and Properties of Novel Cationic Gemini Surfactants with Rigid Amido Spacer Groups

A series of novel cationic gemini surfactants with rigid amido groups inserted as the spacers, named C ₁₂ ‐PPDA‐C ₁₂ , C ₁₄ ‐PPDA‐C ₁₄ and C ₁₆ ‐PPDA‐C ₁₆ , were synthesized by a two‐step reaction with dimethyl terephthalate, N,N‐dimethyl propylene diamine and alkyl bromide as raw materials. The chemical structures of the prepared compounds were confirmed by IR, ¹H and ¹³C NMR and element analysis. Surface activity properties of the synthesized compounds were investigated by surface tension, electrical conductivity and fluorescence. Increasing the number of carbon atoms in the hydrophobic alkyl chain, decreased the critical micelle concentration (CMC), surface tension at the CMC and the minimum surface area. Other relevant properties including foaming ability and emulsion stability were investigated. The results indicated that the synthesized gemini surfactants possess good surface properties, emulsifying properties and steady foam properties.     

New optically active poly(amide-imide)s based on N,N′-(pyromellitoyl)-bis-L-amino acid and 1,3-bis(4-aminophenoxy) propane: Synthesis and characterization

Five new poly(amide-imide)s 8a–e were synthesized through the direct polycondensation reaction of five chiral N,N′-(pyromellitoyl)-bis-L -amino acids 3a–e with 1,3-bis(4-aminophenoxy) propane 7 in a medium consisting of N-methyl-2-pyrrolidone, triphenyl phosfite, calcium chloride, and pyridine. The polycondensation reaction produced a series of novel poly(amide-imide)s containing trimethylene moiety in the main chain in high yield with inherent viscosities between 0.34 and 0.65 dL/g. The resulted polymers were fully characterized by means of FTIR spectroscopy, elemental analyses, inherent viscosity, and solubility tests. Thermal properties of these polymers were investigated by using thermal gravimetric analysis (TGA) and differential thermal gravimetric (DTG). All of the polymers were soluble at room temperature in polar solvents such as N,N-dimethyl acetamide, N,N-dimethyl formamide, dimethyl sulfoxide, and N-methyl-2-pyrrolidone. N,N′-(pyromellitoyl)-bis-L -amino acids 3a–e were prepared in quantitative yields by the condensation reaction of pyromellitic dianhydride (1,2,4,5-benzenetetracarboxylic acid 1,2,4,5-dianhydide) 1 with L -alanine 2a , L -valine 2b , L -leucine 2c , L -isoleucine 2d , and L -phenyl alanine 2e in acetic acid. Also 1,3-bis(4-aminophenoxy) propane 7 was synthesized by using a two-step reaction. At first 1,3-bis(4-nitrophenoxy) propane 6 was prepared from the reaction of 4-nitrophenol 4 with 1,3-dibromoprapane 5 in NaOH solution. Then, dinitro compound 6 was reduced by using Na₂S. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Imidazolium,Pyridinium and Dimethyl-Ethylbenzyl Ammonium Derived Compounds as Mixed Corrosion Inhibitors in Acidic Medium

Seven cationic surfactants: 1-methyl-3-tetradecyl imidazolium bromide, 1-methyl-3-hexadecyl imidazolium bromide, N,N-tetradecyl pyridinium bromide, N,N-hexadecyl pyridinium bromide, N,N-dimethyl-N-ethylbenzyl ammonium bromide, N,N-dimethyl-N-ethylbenzyl ammonium laurate and N,N-dimethyl-N-ethylbenzyl ammonium acetate, were investigated at different doses (10, 25, 50, 100, and 200 ppm) as corrosion inhibitors for steel grade API 5L X52 in hydrochloric acid 2 M using a weight loss technique, impedance and polarization resistance methods. The corrosion inhibition of steel grade API 5L X52 of the cationic surfactants was attributed to their molecular structure (heterocyclic ring, hydrophobic chain length and counterion) that enhances adsorption onto steel surface. The best protective efficiency of the film was higher than 90% (N,N-Dimethyl-N-ethylbenzyl ammonium acetate). It is important to know how organic inhibitor films grown on the metallic surface in order to achieve superior corrosion inhibition, hence experimental findings were described by Langmuir adsorption isotherm. The Electrochemical Impedance Spectroscopy spectrums were fitted by means of the Voigt model.     

Preparation of a New Oligomeric Surfactant: N,N,N′,N″,N″-Pentamethyl Diethyleneamine—N,N″-Di-[Tetradecylammonium Bromide] and the Study of its Thermodynamic Properties

A new oligomeric surfactant: N,N,N′,N″,N″- pentamethyl diethyleneamine—N,N″-di-[tetradecylammonium bromide] referred to as 14-2-N(CH₃)-2-14 was synthesized, purified and characterized by Elemental Analysis, ¹H and ¹³C NMR and Electrospray. The micellar properties of this compound were determined by electrical conductivity and surface tension methods. Optical microscopy was also employed to study the behavior of anhydrous surfactant and the binary water/surfactant system as a function of temperature. The critical micellar concentration (cmc), degree of counterion binding and thermodynamic parameters of micellization (standard molar Gibbs energy, enthalpy and entropy of micellization) were determined by electrical conductivity measurements in the temperature range [24–54 °C]. Surface tension measurements also provide information about the dependence of the surface tension at the cmc (γ_cmc), pC₂₀ (negative logarithm of the surfactant’s molar concentration C₂₀, required to reduce the surface tension by 20 mN/m, the surface excess (Γ_max) at air/solution interface, the minimum area per surfactant molecule at the air/solution interface (Amin), surface pressure at the cmc (П_cmc), critical packing parameter(CPP) and the standard free energies of micellization ( \Updelta G_m⁰\Updelta G_{m}^{0}) and of adsorption ( \Updelta G_\textads⁰ \Updelta G_{\text{ads}}^{0} ).     

Synthesis,characterization and antibacterial activity of quaternized <Emphasis Type="Italic">N</Emphasis>,<Emphasis Type="Italic">O</Emphasis>-(2-carboxyethyl) chitosan

N,O-(2-carboxyethyl)chitosan (N,O-2-CEC) was prepared from chitosan with 3-chloropropionic acid as modifying agent and NaOH as catalyst. Different quaternary ammonium groups were introduced into N,O-2-CEC by the reaction between N,O-2-CEC and different 2,3-epoxypropyl trialkyl ammonium chlorides in the presence of 25% NaOH aqueous solution, and obtained different quaternized N,O-2-carboxyethyl chitosans (QCECs). Structures of QCECs were characterized by FT-IR, ¹HNMR and gel permeation chromatography (GPC). Antimicrobial activity of QCECs was evaluated against a gram-negative bacterium Escherichia coli and a gram-positive bacterium Staphylococcus aureus. Compared with N,O-2-CEC and quaternized chitosans, the QCECs had much stronger antimicrobial activity, which increased with increasing chain length of the alkyl in the quaternary ammonium groups. The presence of benzyl in quaternary ammonium groups could endow QCECs with much better antimicrobial activity.     

Solution properties of a hyamine based on N,N‐dimethyl diallyl ammonium chloride–acrylamide copolymer

A hyamine based on N,N‐dimethyl diallyl ammonium chloride–acrylamide copolymer was successfully synthesized in this study. Solution properties of this hyamine including electrical conductivity and viscosity behavior were studied in detail, and effects of temperature and counter ion concentration on electrical conductivity of the solution were also discussed. It was found that a solution of hyamine in water showed a typical viscosity behavior of polyelectrolytes, which followed the Fuoss equation. With the increase of ion radius (cationic ion or anionic ion), or with the increase of salt concentration, the shrinkage degree of the polymer chain increased, with a concomitant decrease in reduced viscosity and intrinsic viscosity and an increase of Huggins constant. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 90: 765–771, 2003     

A novel twin-tailed hydrophobically associating copolymer: synthesis, characterization and solution properties

Novel twin-tailed hydrophobically associating copolymers (DDSPAM) were prepared by micellar copolymerization of acrylamide (AM) and sodium vinylsulfonate with N,N-didecyl-N-methyl-N-(4-vinylbenzyl)ammonium chloride in an aqueous solution. The structure and composition of DDSPAM were characterized by ¹H-NMR and elemental analysis. While the molecular weights of the copolymers were obtained via static light scattering, the hydrodynamic radius of aggregates was investigated using dynamic light scattering. The critical micellar concentration cmc and γ _cmc values of DDSPAM were measured using fluorescence and later correlated with the values obtained from surface tension measurements. In addition, the viscosity stability studies of DDSPAM and hydrolyzed polyacrylamide (HPAM) revealed that DDSPAM, with twin tails of hydrophobic groups, exhibited better salt tolerance as well as temperature resistance compared to HPAM.     

Interfacial and Solution Behavior of Amphiphilic Drug and Counterion‐Coupled Gemini (COCOGEM) Surfactants

The critical micelle concentrations (cmc) of mixed systems comprising an amphiphilic drug amitriptyline hydrochloride and counterion‐coupled gemini surfactants 12‐6‐12, 14‐6‐14, or 16‐6‐16 [1,6‐bis(N,N‐alkyldimethylammonium) adipate] were determined using tensiometry. The results were analyzed in the light of different theoretical models from Rosen, Clint, Rubingh, and Motomura. The cmc values decrease with increasing mole fraction of surfactant (α₁). The cmc_id values (cmc value at ideal mixing conditions) also decrease with α₁ but remain above the experimental cmc values. This means that the mixed micelles form as a result of attractive interactions. These interactions are also seen in surface excess concentration (Γ_max) and minimum area per molecule (A_min) data: Γ_max increases and A_min decreases. Both Rosen's and Rubingh's models indicate synergistic interactions (interaction parameter, β^m and β^σ, values are negative). The β^m values are larger in magnitude than β^σ for 14‐6‐14 and 16‐6‐16 systems, whereas the reverse is the case with 12‐6‐12 because the surfactant's short chain makes adjustment in the core difficult for both components.