Kinetic study of Hg(II)-promoted substitution of cyanide from hexacyanoferrate(II) in an anionic surfactant medium by 2,2′-bipyridine

The kinetic investigation of Hg(II)-promoted reaction between [Fe(CN)₆]⁴⁻ and 2,2′-bipyridine (Bipy) has been performed in anionic sodium dodecyl sulfate (SDS) micellar medium by recording the surge in absorbance at 400 nm, corresponding to ultimate reaction product [Fe(CN)₄ Bipy]²⁻ using UV–visible spectrophotometer. Pseudo-first-order condition has been used to examine the progress of reaction as a function of temperature, [Fe(CN)₆⁴⁻], ionic strength, [SDS], pH, [Hg²⁺], and [Bipy] by changing one parameter at a time. The results exhibit that [Hg²⁺], [SDS], and pH are the decisive parameter showing maximum reaction rate at 1.5 × 10⁻⁴ mol dm⁻³, 6.0 × 10⁻³ mol dm⁻³, and 3.8, respectively. [Fe(CN)₆]⁴⁻ does not show any appreciable effect on the critical micellar concentration (CMC) of SDS as the polar head of SDS and [Fe(CN)₆]⁴⁻ both are negatively charged. Variable order kinetics was observed for [Fe(CN)₆]⁴⁻ and Bipy in their examined concentration range. The reverse response observed in the reaction rate with [KNO₃] shows a negative salt effect. The K⁺ provided by K₄[Fe(CN)₆] and KNO₃ decreases the repulsion between the negatively charged heads of the surfactant molecules thereby decreasing the CMC of SDS. The negative value for the entropy of activation also supports the interchange dissociative (I_d) mechanism recommended by us.     

Effect of 1-pentanol on the styrene emulsion polymerization

The influence of 1-pentanol (C₅OH) on the ST emulsion polymerization mechanisms and kinetics is investigated. The CMC of the ST emulsions first decreases rapidly and then levels off when the C₅OH concentration ([C₅OH]) increases from 0 to 72 mM. The effect of C₅OH increases to a maximum and then decreases when the SDS concentration ([SDS]) increases from 2 to 18 mM. At [SDS]=2 mM, homogeneous nucleation controls the polymerization kinetics regardless of [C₅OH]. At [SDS]=4 mM, the effect of [C₅OH] appears due to the transition from homogeneous nucleation to a mixed mode of particle nucleation (homogeneous nucleation and micellar nucleation) occurs when [C₅OH] increases from 0 to 72 mM. The effect of [C₅OH] is the strongest at [SDS]=6 mM since the particle nucleation mechanisms span homogeneous nucleation (low [C₅OH]), a mixed mode of particle nucleation (homogeneous nucleation and micellar nucleation) (medium [C₅OH]) and micellar nucleation (high [C₅OH]). At [SDS] >6 mM, in which micellar nucleation controls the polymerization kinetics, the effect of [C₅OH] decreases rapidly with increasing [SDS].     

Characteristics of solubilization and encapsulation of fullerene C60 in non-ionic Triton X-100 micelles

The solubilization and encapsulation of monomeric C₆₀ in Triton X-100 micelles were investigated. Characteristic hydrophobic interactions of the type π-π and CH-π between the Triton X-100 micelle and C₆₀ resulted in stable aqueous dispersions of C₆₀ in the micellar medium, as evidenced from UV-vis, fluorescence emission and micro-Raman spectroscopy. Cyclic voltammetry of C₆₀ encapsulated Triton X-100 in aqueous 5 mM LiClO₄ solution revealed a quasi-reversible one-electron reduction peak with E_1/2 = −0.61 V and a reversible reduction peak at E_1/2 = −1.11 V vs. Ag/AgCl reference electrode at a scan rate of 10 mV s⁻¹, a redox behaviour drifting substantially from that of pure C₆₀. An onset concentration of ∼0.025 mM for C₆₀ aggregation in the micellar core was substantiated from the characteristic absorption spectral broadening and quenching of pyrene fluorescence. The molar solubilization capacity of C₆₀ in aqueous Triton X-100 micellar solution was estimated spectrophotometrically to be 0.22.     

Activity of horseradish peroxidase in aqueous and reverse micelles and back‐extraction from reverse‐micellar phases

Studies on the activity of the enzyme horseradish peroxidase (HRP) have been carried out in micellar as well as reverse‐micellar media. The activity of the enzyme was studied in the presence of different classes of surfactants – ionic as well as non‐ionic. In aqueous media, the activity of the enzyme varied depending on whether the concentration of the surfactant used was above or below the critical micellar concentration (CMC). The enzyme was also studied in reverse‐micellar systems. HRP was introduced into the reverse micellar phase by the injection method and its activity within the reverse micelles was determined. The effect of water to surfactant ratio (W_o) on activity within reverse micelles was studied, and an almost two‐fold increase in activity was seen when the enzyme was encapsulated within reverse micelles of aqueous phase fractional hold‐up (?) of 0.0072 (v/v) consisting of sodium bis‐(2‐ethylhexyl) sulfosuccinate (AOT) in isooctane at a W_o of 20. The activity of HRP was measured over a wide range of AOT concentrations having different W_o values. Back‐extraction of HRP from these reverse micelles was carried out at varying ionic strengths of phosphate buffer. Back extraction was found to be highest at pH 7.0 in 40 mol m^?3 phosphate buffer and 100 mol m^?3 sodium chloride. © 2001 Society of Chemical Industry     

Importance of micellar relaxation time on detergent properties

As we enter the new millennium, manufacturers of laundry detergents would like to provide new products for the twenty-first century. With the goal of achieving new and better performance characteristics, design strategies for research and development should be defined. This paper highlights the importance of micellar relaxation kinetics in processes involved in detergency. Earlier Shah and coworkers showed that the stability of sodium dodecyl sulfate (SDS) micelles plays an important role in various technological processes. The slow relaxation time (τ₂) of SDS micelles, as measured by the pressure-jump technique, was in the range of 10⁻⁴ to 10¹ s, depending on the surfactant concentration. A maximal relaxation time and thus a maximal micellar stability was found at 200 mM SDS (5 s), corresponding to the least-foaming, largest bubble size, longest wetting time of textile, largest emulsion droplet size, and the most rapid solubilization of oil. These results are explained in terms of the flux of surfactant monomers from the bulk to the interface, which determines the dynamic surface tension. More stable micelles lead to less monomer flux and hence to a higher dynamic surface tension. The relaxation time for nonionic surfactants (as measured by the stopped-flow technique) was much longer than for ionic surfactants because of the absence of ionic repulsion between the head groups. The τ₂ was related to dynamic surface-tension experiments. Stability of SDS micelles can be greatly enhanced by the addition of long-chain alcohols or cationic surfactants. In summary, relaxation time data of surfactant solutions enable us to predict the performance of a given surfactant solution. Moreover, results suggest that one can design appropriate micelles with specific stability, or τ₂, by controlling surfactant structure, concentration, and physicochemical conditions, as well as by mixing anionic/cationic or ionic/nonionic surfactants for a desired technological application, e.g., detergency.     

Inverse microemulsion copolymerization of butyl acrylate and acrylamide: kinetics,colloidal parameters and some model applications

The inverse microemulsion copolymerization of acrylamide and butyl acrylate initiated by ammonium peroxodisulphate, a water‐soluble initiator, and stabilized by anionic emulsifiers sodium bis‐2‐ethylhexylsulfosuccinate and sodium dodecylsulphate (SDS) has been studied. An increase of SDS concentration was observed to increase both the rate of polymerization and the particle size. The average number of radicals per particle (n?) is much below 0.5, which indicates desorption of monomeric radicals from polymer particles. The exit (desorption) rate constants k′_des (cm² s^?1) and k_des (s^?1) were evaluated as a function of SDS concentration (or the particle size) according to the Ugelstad/O'Toole (I), Nomura (II) and Gilbert (III) models. The value of k_des (s^?1) decreases with increasing particle size (or SDS concentration) for all three (I, II and III) models. A complex trend appears for k′_des (cm² s^?1): the Ugelstad/O'Toole model estimates a decrease, the Nomura model finds no variation and the Gilbert model estimates even a slight increase in k′_des with increasing SDS concentration. Copyright © 2006 Society of Chemical Industry     

Synthesis and self‐assembly behavior of pH‐responsive amphiphilic copolymers containing ketal functional groups

Polymeric micelles that are responsive to pH are particularly attractive for application in drug delivery systems. In this study, one type of amphiphilic block copolymers with hydrophobic building blocks bearing pH‐sensitive ketal groups was designed. In an acidic environment, the polarity transfer from amphiphile to double hydrophile for this copolymer destroyed the driving force of micelle formation, which triggered the release of encapsulated hydrophobic molecules. The amphiphilic block copolymers monomethoxy‐poly(ethylene glycol)‐block‐poly(2,2‐dimethyl‐1,3‐dioxolane‐4‐yl)methyl acrylate (MPEG‐block‐PDMDMA) was fabricated by atom transfer radical polymerization using MPEG‐Br as macroinitiator. The critical micelle concentration of various compositions of this copolymer in aqueous solution ranged from 4.0 to 10.0 mg L^?1, and the partition equilibrium constant (K_v) of pyrene in micellar solutions of the copolymers varied from 1.61 × 10⁵ to 4.86 × 10⁵. Their overall effective hydrodynamic diameters from dynamic light scattering measurements were between 80 and 400 nm, and the micellar morphology showed spherical geometry as investigated using transmission electron microscopy. At pH = 1.0, all of these polymeric micelles presented 100% payload release in 24 h of incubation, while at pH = 3.0, nearly 70 and 25% of pyrene was released for MPEG‐block‐PDMDMA (44/18) and MPEG‐block‐PDMDMA (44/25) in 260 h, respectively. The pH‐responsive MPEG‐block‐PDMDMA polymeric micelles having good encapsulation efficiency for hydrophobic drugs are potential candidates for biomedical and drug delivery applications. Copyright © 2010 Society of Chemical Industry     

Pd@Al2O3‐Catalyzed Hydrogenation of Allylbenzene to Propylbenzene in Methanol and Aqueous Micellar Solutions

The palladium on alumina (Pd@Al₂O₃)‐catalyzed hydrogenation of allylbenzene to propylbenzene was studied in methanol and aqueous micellar solutions of sodium dodecyl sulfate (SDS), decyltrimethylammonium bromide (DTAB), and t‐octylphenoxypolyethoxyethanol (TX‐100). Over Pd@Al₂O₃, propylbenzene was obtained via direct hydrogenation of allylbenzene and isomerization to β‐methylstyrene which was hydrogenated afterwards. In aqueous micellar solutions, the reaction was faster than in pure water, but slower than in methanol due to lower hydrogen solubility. In the H₂O/SDS system, a higher activation energy was obtained than in methanol. For the investigated surfactants, the initial reaction rate in the micellar systems decreased in the order SDS > TX‐100 > DTAB.     

The effect of micellar lifetime on the rate of solubilization and detergency in sodium dodecyl sulfate solutions

The slow relaxation time (τ₂) of sodium dodecyl sulfate (SDS) micelles, measured by the pressure-jump technique, was maximum at 200 mM concentration at 25°C, indicating that the most stable micelles are formed at this concentration. This is presumably related to the optimum molecular packing in the micelle. The rate of solubilization of benzene and Orange OT dye into SDS solutions was also maximum at 200 mM concentration. The results are explained as follows: The distance between micelles (i.e., intermicellar distance) decreases as the surfactant concentration (or the number of micelles) increases, resulting in a stronger electric repulsion between micelles. Therefore, the micelles become more rigid, due to the compressive force of intermicellar repulsion, as the concentration increases up to 200 mM SDS. With further increase in the SDS concentration, the micellar shape changes from spherical to cylindrical to accommodate more surfactant molecules in the solution and to minimize the free energy of the system. The interior of the tightly packed micelles is more hydrophobic than that of loosely packed micelles and, therefore, the tightly packed micelles induce rapid solubilization of nonpolar molecules (e.g., benzene, Orange OT) into these micelles.     

Microemulsion copolymerization of vinyl acetate and butyl acrylate using a mixture of anionic and non-ionic surfactants

Monomer mixtures of vinyl acetate (VAc)/butyl acrylate (BuA) were polymerized in batch reactions at 60 °C with potassium persulfate as the initiator in microemulsions consisting of VAc:BuA (85:15 wt/wt)/water/sodium dodecyl sulfate (SDS)/polyoxyethylene (23) dodecyl ether (3:1 wt/wt). The effect of the concentration of the monomer mixture on the kinetics was studied. It was found that, as the total monomers concentration ([M]₀) increases, the polymerization rate increases also, and that the maximum polymerization rate is proportional to [M]₀^1.26. Particle size increases with total monomers concentration. In all cases, final average particle diameter was less than 50 nm. Particle number density is independent of total monomers concentration. A mathematical model that takes into account the partition of monomers between the different phases during polymerization using a minimum of adjustable parameters was applied to simulate the experimental data. A correlation for the radical desorption coefficient, which is a function of the rate of monomer chain transfer and of the probability of desorption, was used in the model. Radical capture by micelles and particles was assumed to occur by diffusion. The model takes into account both micellar and homogeneous nucleation. Good agreement between the model and the experimental results was observed.     

Hydrophobic microblock length effect on the interaction strength and binding capacity between a partially hydrolyzed microblock hydrophobically associating polyacrylamide terpolymer and surfactant

Poly(acrylamide/sodium acrylate/N‐dodecyl acrylamide)s [poly(AM/NaAA/C₁₂AM)s] with different hydrophobic microblock lengths (N_H's) were prepared by the micellar copolymerization of acrylamide and sodium acrylate with a low amount of N‐dodecyl acrylamide (0.2 mol %), and the molecular structure was characterized by Fourier transform infrared spectroscopy, ¹H‐NMR, and static light scattering. A combination of experiments involving viscosity measurement, fluorescence, and conductometry was applied to investigate the effect of N_H on the interaction strength and binding capacity between poly(AM/NaAA/C₁₂AM)s and C₁₂H₂₅SO₄Na [sodium dodecyl sulfate (SDS)]. The viscosity, I₃/I₁ (the intensity ratio of the third vibrational band to the first band of pyrene molecules), and conductivity of the mixed system of copolymers with SDS all had different variation trends with the concentration of SDS. The binding capacity of the copolymers with SDS was calculated according to quantitative differences between the critical micelle concentration of the pure SDS solution and the mixed system. All of the results show that the interaction strength of SDS with the copolymers rose, and the binding capacity decreased with increasing N_H. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40633.     

Micellar enhanced ultrafiltration and activated carbon fibre hybrid processes for copper removal from wastewater

Several series of experiments were conducted to investigate copper removal from artificial suspension in micellar enhanced ultrafiltration (MEUF) and activated carbon fibre (ACF) hybrid processes. Sodium dodecyl sulphate (SDS) was used as a surfactant. Copper removal increased with the increase of molar ratio of copper to SDS, operating retentate pressure and initial permeate flux. Permeate flux decreased with the increase of molar ratio of copper to SDS. Specific and relative fluxes declined, respectively, with the increase of retentate pressure and initial permeate flux. Based on removal efficiency and permeate flux, initial permeate flux of 1.05 m³/m²/day, copper to SDS molar ratio of 1:30 (9.44 mM of SDS), and operating retentate pressure of 1.4 bar were found to be the optimum operating parameters for 0.5 mM or less initial copper concentration. Average copper removal at the optimised condition was 98% and the corresponding permeate copper concentration was less than 1 mg/L. Adsorptive capacity of activated carbon fibre (ACF) for SDS was 170 mg/g. Langmuir isotherm equation gives a better fit with the experimental results compared to the Freundlich isotherm equation. Overall SDS removal efficiency of two sets of ACF unit in series was 85%.     

Investigating the Location of Propyl Gallate at Surfaces and Its Chemical Microenvironment by <Superscript>1</Superscript>H NMR

The location and the resulting chemical microenvironment of the antioxidant propyl gallate (PG) was studied in micellar solutions using the cationic emulsifier cetyl trimethyl ammonium bromide (CTAB), the anionic emulsifier sodium dodecyl sulphate (SDS) and the non-ionic emulsifier Brij 58 (polyoxyethylene-20-cetyl ester). T ₁ relaxation time of the aromatic protons of PG was investigated in micellar solutions and compared with that in aqueous solution in the absence of emulsifier. The relaxation time of the PG portion that is solubilized in the micelle (T _1,eff) was calculated from the partition behavior of PG in micellar solution. From the 1D-¹H spectrum, the alteration in the electron density of the aromatic protons and the alteration in the peak shape of the emulsifier headgroup and alkyl chain proton signals were indicative of the location of propyl gallate in the different micelles. Nuclear Overhauser effects (NOE) made it possible to deduce the exact location of PG by calculation of the relative NOEs. Marked differences were found for the location of PG in CTAB, SDS and Brij 58 micelles. PG was found to be located in the palisade layer of CTAB micelles, in the region of the polyoxyethylene chain of Brij micelles and in the Stern layer of SDS micelles. For careful study of the location of antioxidants and therefore to be able to characterize the chemical microenvironment of the antioxidants is crucial for understanding differences in antioxidant activities as a function of lipid surfaces. The application of spectroscopic methods may help to optimize the antioxidant activity to inhibit lipid oxidation at surfaces that are formed in a wide range of foods (emulsions), cosmetics, pharmaceuticals (emulsions and carrier systems) and of biological membranes (LDL-particles).     

A Comparative Study on the Aggregation and Thermodynamic Properties of Anionic Sodium Dodecylsulphate and Cationic Cetyltrimethylammonium Bromide in Aqueous Medium: Effect of the Co-solvent N-Methylacetamide

The effect of co‐solvent N‐methylacetamide (NMA) (0.035, 0.046, 0.127, and 0.258 mol kg^?1) on the micellization behaviour of anionic surfactant sodium dodecylsulphate (SDS) (3.21–10.35 mmol kg^?1) and cationic surfactant cetyltrimethylammonium bromide (CTAB) (0.19–3.72 mmol kg^?1) in aqueous solution was explored by employing conductivity measurements at different temperatures (298.15–313.15 K). The critical micelle concentration (CMC) values for SDS and CTAB in aqueous solutions of NMA were determined from the conductivity versus surfactant concentration plots. The variations in the CMC values of SDS with NMA concentration are in striking contrast to those observed in the case of CTAB. The various relevant thermodynamic parameters of micellization, viz. standard enthalpy change, ΔH_m^o, standard entropy change, ΔS_m^o, and standard Gibbs free energy change, ΔG_m^o, were determined using the temperature variation of the CMC values and counterion binding. The results not only relate these thermodynamic parameters to the consequences of intermolecular interactions but are also able to differentiate between SDS–water–NMA and CTAB–water–NMA systems in terms of contributions from head groups as well as alkyl chains of surfactants.     

Elucidation of Interactions between l-Ascorbic Acid and Mixed Micellar Aggregates of Catanionic {Sodium Dodecylsulfate + Cetyltrimethylammonium Bromide} Surfactants via Physicochemical and Spectroscopic Studies

Surfactant micelles mimic the microenvironment present in biological systems and can act as a medium for antioxidant studies. Moreover, the thermodynamic profile of micellization and spectroscopic studies provides very good information about interactions in these systems. Thus, the mixed micellar behavior of sodium dodecylsulfate (SDS) and cetyltrimethylammonium bromide (CTAB) at varying mole fractions of SDS was studied in (0.01, 0.02, and 0.03) mol kg⁻¹ ʟ-ascorbic acid_(aq) solutions with the aid of various techniques viz., conductivity, density and sound velocity, and spectroscopy. From the CMC values of the mixed surfactants, the degree of ionization (β) and thermodynamic parameters (, , and ) were evaluated at 298.15, 308.15, and 318.15 K. The UV absorption spectra were recorded in (1–3) × 10⁻⁴ mol kg⁻¹ ʟ-ascorbic acid_(aq) solutions at various mole fractions of SDS. The proton (¹H) NMR spectra of mixed (SDS + CTAB) surfactants were studied in (0.01–0.03) mol kg⁻¹ ʟ-ascorbic acid solutions. Hydrodynamic diameters (D_h) of mixed micellar aggregates were obtained from the dynamic light scattering (DLS) studies. The present studies suggest the predominance of ionic-hydrophilic interactions between the ionic head groups {O-SO₃⁻ or N⁺ (CH₃)₃} of surfactants and the polar (–OH, –C=O and –O–) sites of ʟ-ascorbic acid.     

The effect of a surfactant on mixer—settler operation

A single stage mixer—settler was used to investigate the effect of surfactant on the mass transfer rate in the system water—HNO₃—30 vol.% TBP/dodecane. The interfacial tension of this system first falls then rises with increasing sodium lauryl sulphate (SLS) concentration. The addition of SLS makes the stage efficiency, which is closely related to k_ha, the product of the individual mass transfer coefficient of HNO₃ in the aqueous phase, and average interfacial area per unit volume of mixing chamber, to increase significantly due to an increase in the value of a. A maximum k_ha value of 0.53 litres^?1, a minimum value of interfacial tension, and phase inversion which converted the aqueous phase from continuous to dispersed were observed at around the critical micellar concentration (100 parts 10^?6) of SLS in the system of an aqueous to organic phase ratio of 0.2.     

Packing of polyethylene oxide chains in a mixed micelle

The effects of an anionic surfactant, sodium dodecyl sulfate (SDS), on the micellar properties of a nonionic surfactant such as homogeneous heptaethylene glycol n-dodecyl ether (7ED) have been studied by the charge transfer solubilization of 7,7,8,8-tetracyanoquinodimethane, pNa, and electric conductivity measurements. Attention has been paid to changes in packing of polyethylene oxide chains in the mixed micelle and to binding of the counterions onto the micelle surface. All measurements were made on solutions ranging in 7ED concentration from 1 × 10⁻⁶ to 1×10⁻¹ M, while the SDS concentration was maintained constant. It has been shown that the binding of Na⁺ ions to the mixed micelle occurs in the 7ED concentration region where the packing of polyethylene oxide chains in the micelle is loose, while release of Na⁺ ions is observed when the packing is compact. The results of electric conductivity correspond well with those mentioned above. However, in the region of high 7ED concentration, the decreasing mobility of the mixed micelles affects the electric conductivity more than the increasing degree of ionic dissociation of the micelle.     

Photochemische Primärprozesse von Xanthenfarbstoffen. II. Blitzlichtspektroskopische Untersuchungen zum Einfluß von anionischen Mizellen auf die photochemischen Primärprozesse von Selenopyronin

Photochemical Primary Processes of Xanthene Dyes. II. Investigations of the Influence of Anionic Micelles on the Primary Processes of Selenopyronine by Flash Excitation In aqueous solutions containing anionic micelles, the dye cations of selenopyronine are present at the micellar surface. If the concentration of the dye ions is much lower than the concentration of micelles, only monomolecular triplet decay (k₁^aM = 2 · 10⁻³s⁻¹) is observed. Under these conditions, the half-oxidized and half-reduced form of selenopyronin is not formed. If the concentration of the dye ions is much higher than the concentration of micelles, two or more dye ions are present at every micelle, and a fast bimolecular decay of the triplet state during the flash is observed. The quenching of the triplet state with p-benzoquinone (k₇^aM = 1,9 · 10⁹ l/mol s), DABCO (k₁₀^aM = 1,6 · 10⁷ l/mol s) and EDTA (k₁₁^aM = 1,3 · 10⁵ l/mol s) and the decay processes of the half-reduced and half-oxidized form in the micellar solution are investigated.     

Effect of Alkanediyl-α,ω-Type Cationic Dimeric (Gemini) Surfactants on the Reaction Rate of Ninhydrin with [Cu(II)-Gly-Tyr]+ Complex

The effect of gemini (16‐s‐16, s = 4, 5, 6) surfactants on the reaction rate of ninhydrin with [Cu(II)‐Gly‐Tyr]⁺ complex was determined using a spectrophotometric technique. The ninhydrin concentration was kept in excess in order to maintain pseudo‐first‐order conditions. The reaction followed irreversible first‐ and fractional‐order kinetics with respect to [Cu(II)‐Gly‐Tyr]⁺ and [ninhydrin], respectively. It is found that gemini surfactants effectively catalyze the reaction. The rate constants (k_ψ) first increase and then become relatively constant with increasing gemini surfactant concentration similar to conventional cetyltrimethylammonium bromide. At higher gemini surfactant concentration a third region of increasing k_ψ is observed. The unusual third region is ascribed to changes in micellar morphology. The kinetic data has been analyzed using a micellar pseudo‐phase model.     

pH‐responsive poly(ethylene glycol)‐poly(ϵ‐caprolactone)‐poly(glutamic acid) polymersome as an efficient doxorubicin carrier for cancer therapy

The synthesis, characterization and potential application in the doxorubicin (Dox) delivery system of a biodegradable polypeptide‐based block copolymer, poly(ethylene glycol)₂₀₀₀‐poly(?‐caprolactone)₆₀₀₀‐poly(glutamic acid)₁₀₀₀ (PEG₂₀₀₀‐PCL₆₀₀₀‐PGA₁₀₀₀), was investigated. The copolymer was synthesized via ring‐opening polymerization and characterized by ¹H NMR and Fourier transform IR. The synthesized copolymer could self‐assemble into aggregates and the critical aggregation concentration was 0.23 mg mL^?1. Transmission electron microscopy indicated that spherical polymersomes formed with a desirable size about 180 nm. Therefore Dox was encapsulated into these polymersomes, and then we investigated its applications in a drug delivery system. These Dox‐loaded polymersomes (PolyDox) were characterized by dynamic light scattering, zeta potential and pH responsiveness measurements. In vitro drug release indicated that the release rate of drug from PolyDox was pH‐responsive and significantly decreased. The drug pharmacokinetic parameters were improved in comparison to the group treated with free Dox, which proved the prolonged Dox release from PolyDox. A WST‐1 assay indicated a low toxicity and good compatibility of copolymer to cells within 48 h. The results also showed that PolyDox appeared to induce a higher anti‐tumor effect. Cell uptake results indicated that PolyDox displayed higher cellular uptake in A549 cells. Endocytosis inhibition results demonstrated that the internalization of PolyDox was mostly mediated by the fluid‐phase endocytosis pathway. © 2017 Society of Chemical Industry