SDS System Research Articles

Investigation on Growth Kinetics of Hydrate on the Surface of an AC-QS Porous Media Composite System in an SDS System

Investigation on Growth Kinetics of Hydrate on the Surface of an AC-QS Porous Media Composite System in an SDS System

An environment-friendly and highly effective inhibitor for flotation separation of brucite and dolomite in SDS system

ABSTRACT Brucite is a type of mineral resource containing structural water and high contents of Mg, and is popular in refractory and flame-retardant materials. Dolomite is a common mineral associated with brucite, and its presence reduces the purity of brucite and utilization efficiency of resources. Therefore, in the flotation system of sodium dodecyl sulfonate, the selective inhibition characteristic and inhibition mechanism of environment-friendly and highly effective inhibitor sodium alginate (SA) on dolomite in the flotation separation of brucite and dolomite were investigated. The flotation test shows that an SA dosage of 8 mg/L can achieve 77.92% difference in floatability between brucite and dolomite, and the flotation effect was verified using the selectivity index. The measurement of contact angle shows the stability of the SA effect, thereby demonstrating significant SA effect on dolomite and a small effect on brucite. Zeta potential detection and infrared spectrum analysis show that the adsorption capacity between SA and dolomite is considerably stronger than that between SA and brucite, which is another critical reason for the inhibition of SA on dolomite flotation. In addition, the interaction of SA with the two minerals and the reasons for its selective interaction with dolomite were analyzed using X-ray photoelectron spectroscopic detection. SA shows strong interaction with Ca sites and the O in the carboxyl group of the SA structure can chelate Ca.

Influence of the ratio of water and gas on the process of hydrate formation during the explosive boiling of liquefied freon 134a in water with SDS

This work is part of a comprehensive study of a method for obtaining gas hydrates, based on the explosive boiling of a liquefied hydrate-forming gas in a volume of water when the pressure is released. This method is characterized by high productivity. The paper presents the results of an experimental study of hydrate formation in the water + SDS system at different ratios of water and hydrate-forming gas. Freon 134a was used as the hydrate-forming gas. The change in temperature and pressure in the process of hydrate formation is shown.

Synchronized Diaphragmatic Stimulation for Heart Failure With a Reduced Left Ventricular Ejection Fraction Using the VisONE System: A First-in-Patient Study With Extended Population

BackgroundSynchronized diaphragmatic stimulation (SDS) produces localized contractions of the diaphragm gated to the cardiac cycle to transiently modulate intrathoracic pressures, thereby impacting cardiac function for heart failure patients with reduced ejection fraction (HFrEF). This study prospectively evaluated the safety and 1-year effectiveness of SDS in an expanded first-in-patient cohort using multiple implant methods. MethodsSymptomatic patients with HFrEF despite guideline-directed therapy were enrolled. Patients were evaluated at 3, 6 and 12 months for adverse events, quality of life (SF-36 QOL), echocardiography and 6-minute hall walk distance. The SDS system consists of 2 bipolar, active-fixation leads, and an implantable pulse generator. ResultsNineteen men were enrolled (age 63 [57, 67] years, New York Heart Association class II [53%]/III [47%], N-terminal pro B-type natriuretic peptide 1779 [886, 2309] pg/mL, left ventricular ejection fraction 27 [23, 33] %). Three implant techniques (abdominal laparoscopy: sensing and stimulating leads on the inferior diaphragm (n = 15); subxiphoid access for an epicardial sensing lead and abdominal laparoscopy for stimulation on the inferior diaphragm (n = 2); thoracoscopy to place an epicardial sensing lead and a stimulating lead on the superior diaphragm (n = 2)) were employed with 100% success. Patients were unaware of diaphragmatic stimulation. From discharge to 12 months, 6-minute hall walk distance increased (315 [296, 332]m to 340 [319, 384]m; p = 0.002), left ventricular end-systolic volume decreased (135 [114, 140]mL to 99 [90, 105]mL; p = 0.04), and SF-36 QOL improved (physical scale 0 [0, 0] to 25 [0, 50], p = 0.004; emotional scale 0 [0, 33] to 67 [33, 67], p = 0.001). N-terminal pro B-type natriuretic peptide was lower (1784 [944, 2659]pg/mL vs. 962 [671, 1960]pg/mL; p = ns) and left ventricular ejection fraction increased (28 [23, 38]% vs. 35 [31, 40]%; p = ns) although neither reached statistical significance. There were no procedure- or SDS-related adverse events. ConclusionsThese data demonstrate that SDS can be delivered using alternative implantation methods without raising safety concerns and suggest improved outcomes over 1 ​year of follow-up. Adequately powered randomized trials are now needed to confirm these findings.

Synchronized diaphragmatic stimulation for heart failure using the VisONE system: a first-in-patient study.

AimsSynchronized diaphragmatic stimulation (SDS) modulates intrathoracic and intra‐abdominal pressures with favourable effects on cardiac function for patients with a reduced left ventricular ejection fraction (LVEF) and heart failure (HFrEF). VisONE‐HF is a first‐in‐patient, observational study assessing the feasibility and 1 year effects of a novel, minimally invasive SDS device.Methods and resultsThe SDS system comprises a pulse generator and two laparoscopically delivered, bipolar, active‐fixation leads on the inferior diaphragmatic surface. Fifteen symptomatic men with HFrEF and ischaemic heart disease receiving guideline‐recommended therapy were enrolled (age 60 [56, 67] years, New York Heart Association class II [53%] /III [47%], LVEF 27 [23, 33] %, QRSd 117 [100, 125] ms, & N terminal pro brain natriuretic peptide [NT‐proBNP] 1779 [911, 2,072] pg/mL). Implant success was 100%. Patients were evaluated at 3, 6, and 12 months for device‐related or lead‐related complications, quality of life (SF‐36 QOL), 6 min hall walk distance (6MHWd), and by echocardiography. No implant procedure or SDS‐related adverse event occurred, and patients were unaware of diaphragmatic stimulation. By 12 months, left ventricular end‐systolic volume decreased (136 [123, 170] mL to 98 [89, 106] mL; P = 0.05), 6MHWd increased (315 [300, 330] m to 340 [315, 368] m; P = 0.004), and SF‐36 QOL improved (physical scale 0 [0, 0] to 25 [0, 50], P = 0.006; emotional scale 0 [0, 33] to 33 [33, 67], P = 0.001). Although neither reached statistical significance, LVEF decreased (28 [23, 40]% vs. 34 [29, 38]%; P = ns) and NT‐proBNP was lower (1784 [920, 2540] pg/mL vs. 1492 [879, 2028] pg/mL; P = ns).ConclusionsThese data demonstrate the feasibility of laparoscopic implantation and delivery of SDS without raising safety concerns. These encouraging findings should be investigated further in adequately powered randomized trials.

Fast formation kinetics of methane hydrate promoted by fluorinated graphite

Achieving rapid and high gas storage is the primary goal of solidified natural gas storage (SNG) using hydrate. In this study, the formation and decomposition process of hydrate were visualized on the fluorinated graphite (FG) layer for the first time by sapphire visible vessel. The results show that, the addition of FG alone can promote the formation of hydrate. After adding fluorinated graphite into SDS system, the gas storage capacity can be further increased to 165.2 cm3 STP/g H2O, and the average gas storage rate can be further increased to 20.84 cm3·g−1·min−1, which were 154.7% and 507.7% of SDS system, respectively. Meanwhile, the decomposition speed was faster than SDS system. After optimizing the experimental conditions, it was found that FG-1 with superhydrophobicity could stably exist in the gas–liquid interface and cover it when the dosage reached 1 wt% (13.95 mg·cm−2), and the combination with 300 ppm SDS could greatly promote the growth of hydrate. In addition, the excellent stability of FG made the performance of FG + SDS system remain at about 90% after 10 cycles. The unique growth phenomenon of hydrate in fluorinated graphite system was interesting. By building a hydrate formation platform, FG made water pumped from below to the gas phase and hydrate grow upward continuously. In comparison with other reported carbon nanoparticles, FG system maintained similar gas storage and had excellent gas storage speed, which was 1.35 ∼ 40.67 times faster under similar conditions. Therefore, the reusable FG + SDS system with high gas storage capacity and fast growth rate without induction time and mechanical agitation was a promising alternative to hydrate-based SNG technology.

Experimental study and kinetic modeling on THF hydrate formation under a static electric field

Hydrate formation has drawn wide-ranging research attention because of its applications in natural gas storage and transportation, refrigeration technology, seawater desalination, gas separation, capturing greenhouse gases, and energy storage. Also, THF hydrate has been widely investigated in terms of its kinetics, thermophysical properties, and suitability as a replacement for CH4 hydrates in experimental studies. In this work, the kinetics of THF hydrate formation under the impact of an electric field is studied by performing a chemical affinity model. Hence, the effect of an electric field on the chemical affinity model variations involving nucleation temperature and time duration to attain equilibrium needs to be studied from the model point of view. Then, the chemical affinity model under the effect of an electric field is performed for three THF-H2O systems involving solutions containing 10 wt% THF, 19 wt% THF, and 30 wt% THF, and one THF–H2O–SDS system containing 19 wt% THF and 100 ppm SDS. Based on the results, imposing an electric field with a strength of 4.3 × 105 V/m for the mentioned systems causes the nucleation temperature and the hydration reaction time to reach equilibrium to increase. Herein the change in THF consumption versus time in the process of formation and growth of THF hydrate is analyzed by using the chemical affinity model.

Effect of sulfur donor and co-agent as scorch delay system over third monomer EPDM-ENB content

The third monomer is an important characteristic of EPDM rubber, as it directly influences the mechanical and thermal properties of the material. Peroxide vulcanization is often used as a curing system. Furthermore, it increases lifetime and offers dynamic mechanical properties and scorch time lower than sulfur systems. Here, we report the influence of dipentamethylene thiuram tetrasulfide and HVA-2 (N,N-m-phenylene bismaleimide) on peroxide vulcanization at different ENB content on EPDM rubber to reach an ideal condition for the reduction of vulcanization scorch time and improve the its mechanical properties. Tensile strength was highly affected by SDS formulation, increasing to 10 MPa for ENB1.8% and 15 MPa for ENB4.9% and ENB8.5%. Moreover, elongation at break increased from 398 to 650% for ENB1.8%, from 260 to 433% for ENB4.9% and from 290 to 408% for ENB8.5%. Compression set of SDS system was also increased when different ENB contents were compared for a conventional vulcanization system. Tear strength of ENB4.9% and 8.5% enhanced from 25 to around 32 N/mm with the scorch delay system. These results are important for the improvement of gaskets of plate heat exchanger production.

Comparison of the retention of basic compounds in anionic and cationic microemulsion electrokinetic chromatographic systems

Retention of ionizable bases in microemulsion electrokinetic chromatography (MEEKC) has been studied using two different systems with anionic and cationic microemulsions. Microemulsion pseudostationary phase is composed of heptane (oil), 1-butanol (cosurfactant) and sodium dodecyl sulfate (SDS, anionic system) or tetradecyltrimethylammonium bromide (TTAB, cationic system) as surfactant.In contrast with micellar electrokinetic chromatography (MEKC) where the retention of neutral compounds is very different in the two micellar pseudostationary phases (SDS and TTAB, respectively); in MEEKC, neutral compounds present very similar retention factor (k) values in SDS and TTAB microemulsion pseudostationary phases.However, the k vs. pH profiles of protonable bases are very different in the two MEEKC systems. In TTAB system, retention increases with pH because of neutralization of the protonated base and partition of the unionized form into the microemulsion. However, a reversed trend is observed in SDS system. Retention decreases with pH because of the formation of an ionic pair between the protonated base and the anionic SDS, much more retained than the unionized base.Thus, it is demonstrated that the two systems behave very similar in the retention of neutral bases, but completely different for retention of protonated bases.

Thermodynamic insights and molecular environments into catanionic surfactant systems: Influence of chain length and molar ratio

HypothesisImidazolium-based Ionic liquids as new generation cationic surfactants can provide designable alkyl chain length. In the catanionic surfactant systems, the alkyl chain lengths and molar ratios can greatly influence the interactions such as electrostatic and hydrophobic interaction. The variation in these interactions has a significant effect on the molecular environments of the self-assembly structure, and this process is always accompanied by the transition of aggregates and release or consumption of heat. Hence, it is of interest to study the relationship between intermolecular interactions, molecular environments, self-assembly structure and the change in energy of system in the catanionic surfactant mixed systems. ExperimentsThe enthalpy change ΔH of titrations the imidazolium-based into SDS micelle solution was studied to characterize the heat by using isothermal titration calorimetry (ITC) during the transitions of the aggregate structures. The corresponding self-assembly structure was monitored via cryogenic transmission electron microscopy (cryo-TEM). Employing proton magnetic resonance (1H NMR), we focus on the interactions between imidazolium-based ILs and SDS based on the variations in the molecular environments of aggregates. FindingsOf these imidazolium-based ionic liquids/SDS system, the 1-octyl-3-methylimidazolium ([OMIM]Cl)/SDS system shows several features such as intense energy absorption and releasing processes, which indicate the formation of high entanglement wormlike micelles and vesicles. This is related to the formation of self-adjusting state between the SDS and [OMIM]Cl molecules due to the balance between the electrostatic interaction and hydrophobic interaction. Varying the alkyl chain length appears to cause significant differences to the molecular environments. From the molecular environments, three different models about the polarity of the catanionic surfactant molecules are used to explain the balance of the intermolecular interactions.

One-Step Microemulsion Method Synthesis for Monodisperse organic Functionalized silica micro/nano spheres

Monodisperse organic functionalized silica micro/nano spheres have been extensive research due to their special structural features. In this study, the Monodisperse organic functionalized silica micro/nano spheres were prepared by one-step hydrolysis condensation reaction of organosilane including TCPTES, MPTES, CTES, CPTES, UPTES in microemulsion system. It was showed that it was no particles from UPTES in the presence of SDS, and organic silica spheres prepared with CTES and CPTES had uniform particle size and monodispersity. However, organic silica spheres with poor disperse can be obtained from UPTES in the presence of CTAB, due to the physical adsorption between charges. In the contrast with SDS system, other organic silica spheres had poor disperse and nonuniform particle size.

Kinetics of methane hydrate formation in an aqueous solution of thermodynamic promoters (THF and TBAB) with and without kinetic promoter (SDS)

Kinetic studies concerning the combination of thermodynamic promoters (tetra-n-butyl ammonium bromide, TBAB and tetrahydrofuran, THF) and kinetic promoters (sodium dodecyl sulphate, SDS) have not yet been investigated in detail for methane hydrate system suitable for natural gas storage and transportation. In this work, experiments were conducted at an initial pressure conditions of 7.5 MPa and 276.15 K for pure water, SDS, TBAB, (TBAB + SDS), THF, (THF + SDS) and (THF + TBAB) aqueous systems for various concentrations. Similarly, at 5.5 MPa and 276.15 K, experiments were conducted for pure water, TBAB, (TBAB + SDS), THF and (THF + SDS) aqueous systems for various concentrations. In addition, at 3.0 MPa and 276.15 K, 0.05 and 0.1 mass fraction of TBAB, 0.005 and 0.01 mass fraction of THF and (0.01 + 0.1) mass fraction of (THF + TBAB) aqueous systems have been considered for the experiments. It has been observed that the methane hydrate formed from pure water with SDS shows higher moles of gas consumption per mole of water as compared to other aqueous systems at higher pressure. Also, the use of SDS with THF shows drastic increase in methane consumption as against semiclathrate hydrate/hydrate formed using TBAB aqueous system and pure water. At lower pressure, of about 3 MPa, gas consumption per mole of water in hydrate has found to enhance for a mixed promoter system containing (THF + TBAB) as compared with the other aqueous systems. Theoretical and actual gas storage capacity calculations has also been performed for various concentrations of THF and TBAB aqueous systems. This study essentially helps to understand the behaviour of TBAB and THF aqueous solution with and without SDS and mixed promoter system of (THF + TBAB) for methane hydrate formation desirable for applications like gas storage, transportation and gas recovery using hydrate-based gas separation method.

Studies of the Micellization of Cationic–Anionic Surfactant Systems in Water and Methanol–Water Mixed Solvents

Measurements of the conductance of binary mixtures of cetyltrimethylammonium bromide and sodium dodecylsulfate in pure water and in methanol–water mixed solvent media containing 0.10, 0.20, and 0.30 volume fractions of methanol at 308.15, 318.15, and 323.15 K are reported. The concentration of sodium dodecylsulfate varied from 0.001 to 0.04 mol·L−1 in the presence of ~5.0 × 10−4 mol·L−1 cetyltrimethylammonium bromide. The results showed a sharp increase in the conductance with increasing concentrations of the surfactant mixture. The conductance is found to increase with increasing temperature over the entire concentration range in pure water and in a given mixed solvent medium but is found to decrease with increasing methanol content in the solvent. Estimation of the pre-cmc (S 1) and post-cmc (S 2) slopes for the CTAB–SDS system, to calculate the critical micelle concentration, provides important insight regarding the solution behavior of the mixed surfactants. The critical micelle concentration (cmc) and degree of micellar dissociation (α) of sodium dodecylsulfate in the presence of cetyltrimethylammonium bromide increase in the methanol–water mixed solvent medium. Additionally, the values of cmc and α increase with increasing temperature. The thermodynamic functions for the micellization were calculated at various conditions.

A ternary sensor system based on pyrene derivative-SDS assemblies-Cu2+ displaying dual responsive signals for fast detection of arginine and lysine in aqueous solution

Abstract A new cationic pyrene derivative-based fluorescent probe ( IPy ) was designed and synthesized. This cationic fluorophore with two imidazolium groups can be well-dissolved in aqueous solution and exhibits only monomer emission. The anionic surfactant SDS assemblies can modulate its fluorescence emission and enable both monomer and excimer emission by controlling SDS concentration. The selected IPy /SDS system shows turn-off responses to Cu 2+ , however, the quenching effect of Cu 2+ can be increased by amino acids with high pI values such as arginine (Arg) and lysine (Lys). Therefore, the optimized ternary system based on IPy /SDS/Cu 2+ can function as a highly sensitive and selective fluorescent sensor for these two amino acids, displaying detection limits of 5.2 nM and 14.6 nM for Arg and Lys, respectively. Moreover, this sensor system displays dual responsive signals of “excimer emission off” to low concentrated amino acids (smaller than 10 μM), and “monomer emission on” to high concentrated amino acids (larger than 10 μM). It turns out that low concentrated basic amino acids binds with negative SDS assemblies and facilitate fluorescence quenching of the cationic fluorophore by Cu 2+ , however, the high concentrated basic amino acids induce disassembly of SDS aggregates and lead to leak of the fluorophore back into aqueous environment, which gives rise to monomer emission.

Simultaneous determination of amlodipine besylate and valsartan using a micelle-enhanced first derivative synchronous spectrofluorimetric method and application in their co-formulated tablets

Fluorescence spectra: (I) A and B are emission and excitation spectra of AML (2 μg mL−1) in methanol while A′ and B′ are spectra of AML in a SDS system. (II) A and B are emission and excitation spectra of VAL (2 μg mL−1) in methanol while A′ and B′ are spectra of VAL in a SDS system.

Protein–surfactant aggregate as a potential corrosion inhibitor for mild steel in sulphuric acid: zein–SDS system

A protein–surfactant aggregate (zein–SDS system) acting as corrosion inhibitor for mild steel in H2SO4.

129 EFFECT OF SERUM SUPPLEMENTATION ON AMP-ACTIVATED PROTEIN KINASE (AMPK) ACTIVITY AND LIPID METABOLISM OF IN VITRO-CULTURED BOVINE EMBRYOS

A major problem of embryos cultured in vitro with serum is cytoplasmic lipid accumulation resulting in lower cryotolerance compared with those derived from in vivo or in the absence of serum. AMPK is known as a master regulator of lipid, glucose, and protein metabolism in mammalian cells. Moreover, it has been reported as controller of acetyl-CoA carboxylase α (ACC), the gene responsible for lipid synthesis, and associated with mitochondrial biogenesis and activities in response to oxidative stress. In the present study we aimed to investigate the regulation of AMPK during serum supplementation in vitro. For this, bovine embryos were produced in vitro in SOF media supplemented with oestrous cow serum or fatty acid–free BSA as a system without serum. Triplicate pools (each 10 blastocysts) from each group were used for RNA isolation using Arcturus®PicoPure®RNA Isolation Kit (Life Technologies, USA). Reverse transcription was performed using a combination of Oligo(dT)23 and random primers. Quantification of AMPK catalytic α1 (AMPKA1), ACC, peroxisome proliferator-activated receptor gamma coactivator 1 α (PGC1A), and sterol regulatory element binding transcription factor 2 (SREBP2) transcripts were performed using ABI PRISM® 7000 SDS system (Applied Biosystems, Foster City, CA, USA) using GAPDH as internal control. Normalized log-transformed transcript amount data were statistically analysed using t-test. In addition, AMPK protein was detected by immunofluorescence, mitochondrial activity by MitoTracker® Red (Invitrogen, Carlsbad, CA, USA), and reactive oxygen species by H2DCFDA molecular probe (Life Technologies, USA), and fluorescent intensity signals were visualised under confocal laser scanning microscopy LSM 710 (Carl Zeiss, Germany). Results showed that the expression of AMPKA1, PGC1A, a mitochondrial biogenesis protein, and SREBP2, a regulator of lipid oxidation, were found to be lower (0.4-, 0.2-, and 0.7-fold, respectively; P < 0.05) in blastocysts derived from cultured with serum compared to without serum. By contrast, ACC was up-regulated in blastocysts cultured with serum by 1.8-fold (P < 0.05) compared to without serum. In comparison to blastocyst cultured without serum, a reduced fluorescent intensity was observed in AMPKA1 protein and mitochondrial activity in blastocyst cultured with serum. The presence of serum was also found to be involved in increasing reactive oxygen species accumulation in embryos cultured with serum. The reduced level of AMPK leads to increased ACC and subsequently enhanced conversion of fatty acids into lipid, which is associated with reduced mitochondrial biogenesis protein, elevated reactive oxygen species level, and reduced lipid oxidation by suppression of SREBP2. In conclusion, the presence of serum in in vitro culture environment affected the AMPK activity and thereby genes associated with lipid metabolism in early bovine embryos.

Removal of nickel ions from aqueous solution by micellar-enhanced ultrafiltration, using mixed anionic–non-ionic surfactants

The aim of this study was to investigate the performance of single and mixed surfactants, both non-ionic and anionic, for the removal of nickel from aqueous solution using micellar-enhanced ultrafiltration (MEUF). To achieve this objective, SDS and four non-ionic surfactants with different ethylene oxide (EO) group length were utilized in this work. Furthermore, the synergistic interaction of non-ionic surfactants with SDS micelles was evaluated using β interaction parameter for TX100. The synergistic behavior of non-ionic surfactants in the SDS micelles was demonstrated, in view of the fact that the interaction parameter had a negative value. In this work, the effects of parameters such as SDS and nickel concentration, pressure and pH on the nickel rejection rate were examined in VCF=1.7 at 25°C. The optimum SDS and nickel concentration were determined 8mM and 10ppm (rejection was about 100%), respectively. It was also concluded that in the non-ionic surfactant and SDS system, the nickel rejection rate was considerably enhanced from 56% to 98%, 99%, 96% and 95%, using TX114, TX100, Brij35 and TX405, respectively for a particular concentration of SDS (i.e., 3.2mM). Furthermore, the molar mass concentration and EO group length of non-ionic surfactants in the MEUF had a considerable effect on the performance; i.e., the surfactants with lower molar mass would lead to a higher flux rate and retention.The findings of this study also revealed that as the SDS concentration was increased, the mean micelle size in the SDS and nickel solutions would also decrease accordingly.

Foam stability: The importance of film size and the micellar structuring phenomenon

AbstractThe kinetic stability of SDS foam was probed using Bartsch method at concentrations above CMC (0.03 M and 0.06 M) and below CMC (0.006 M). The foam created from the higher concentration (0.06 M) of micellar solution was more kinetically stable than that produced from the 0.03 M SDS solution and showed a stepwise decrease. On the other hand, the foam produced from SDS surfactant concentration below CMC (0.006 M) did not show such a behaviour and the height remained more or less constant. The effect of the foam lamella size on the bulk foam stability was also investigated. It was found that the critical lamella area is independent of the hydrostatic pressure. And, it took longer to reach the critical lamella area in the 0.06 M SDS system than to reach the critical lamella area in the 0.03 M SDS system. We probed the foam stability by studying the stability of a single foam lamella and observed the micellar layering phenomenon. We found 5 film thickness transitions in the case of 0.06 M SDS system and 3 thickness transitions for 0.03 M SDS system. Therefore, the foam lamella formed from the 0.06 M SDS solution is kinetically more stable than that formed from the 0.03 M SDS solution because the better layering structure in the former case slows down the liquid film drainage. Therefore, this study clearly demonstrates that both the size of the foam lamella and the micellar concentration are important factors in controlling the bulk foam stability.

Cationic brush‐like terpolymer with pH responsive thickening behavior in a surfactant system

A new kind of cationic brush‐like terpolymer was synthesized by copper(I)‐mediated atom transfer radical polymerization (ATRP) of methyl ether poly(ethylene glycol) methacrylate (mPEGMA), poly(propylene glycol) methacrylate (PPGMA) and dimethylaminoethyl methacrylate (DMAEMA) in the presence of ethyl α‐bromoisobutyrate as ATRP initiator. The poly(PEG/PPG/DMAEMA) terpolymer was featured with a cationic backbone containing PDMAEMA segments and amphiphilic side chains composed of hydrophilic PEG and hydrophobic PPG short branches. The copolymer was characterized by 1H NMR, Fourier transform IR and gel permeation chromatography. The thickening behavior of this copolymer in a surfactant system (sodium dodecyl sulfate, SDS) was extensively investigated by a rheological study. It was found that the copolymer can effectively thicken the SDS surfactant system at low concentrations of both copolymer and surfactant. More interestingly, the thickened SDS system by this copolymer showed dramatic pH responsive rheological behavior in the pH range 4–10. Thus the rheological behavior of the thickened SDS system was tunable by pH value. Based on our findings, a novel thickening mechanism is proposed for this kind of cationic brush‐like terpolymer. This kind of cationic brush‐like copolymer would be a new type of rheology modifier for advanced hair/skin care systems. © 2014 Society of Chemical Industry