Effects of Interaction of Ionic and Nonionic Surfactants on Self-Assembly of PEO–PPO–PEO Triblock Copolymer in Aqueous Solution

Adsorption of poly(ethylene oxide)-containing amphiphilic polymers on solid-liquid interfaces: Fundamentals and applications

The adsorption of amphiphilic molecules of varying size on solid-liquid interfaces modulates the properties of colloidal systems. Nonionic, poly(ethylene oxide) (PEO)-based amphiphilic molecules are particularly useful because of their graded hydrophobic-hydrophilic nature, which allows for adsorption on a wide array of solid surfaces. Their adsorption also results in other useful properties, such as responsiveness to external stimuli and solubilization of hydrophobic compounds. This review focuses on the adsorption properties of PEO-based amphiphiles, beginning with a discussion of fundamental concepts pertaining to the adsorption of macromolecules on solid-liquid interfaces, and more specifically the adsorption of PEO homopolymers. The main portion of the review highlights studies on factors affecting the adsorption and surface self-assembly of PEO-PPO-PEO block copolymers, where PPO is poly(propylene oxide). Block copolymers of this type are commercially available and of interest in several fields, due to their low toxicity and compatibility in aqueous systems. Examples of applications relevant to the interfacial behavior of PEO-PPO-PEO block copolymers are paints and coatings, detergents, filtration, and drug delivery. The methods discussed herein for manipulating the adsorption properties of PEO-PPO-PEO are emphasized for their ability to shed light on molecular interactions at interfaces. Knowledge of these interactions guides the formulation of novel materials with useful mesoscale organization and micro- and macrophase properties.

Interaction between bile salt sodium glycodeoxycholate and PEO–PPO–PEO triblock copolymers in aqueous solution

Bile salts can associate to PEO–PPO–PEO block copolymer micelles and disintegrate them depending on the relative block length and molecular weight of the copolymers and bile salt/copolymer molar ratio.

Structural insights into the effect of cholinium-based ionic liquids on the critical micellization temperature of aqueous triblock copolymers

A symmetrical PEG–PPG–PEG triblock copolymer with 82.5% PEG as the hydrophilic end blocks, and PPG as the hydrophobic middle block, was chosen to study the effect of ionic liquids on the critical micellization temperature of block copolymers in aqueous solution.

An investigation of Pluronic P123–sodium cholate mixed system: micellization, gelation and encapsulation behavior

We report impact of sodium cholate on micellization and gelation of P123.

Complexation of triblock reverse copolymer 10R5 with surface active ionic liquids in aqueous medium: a physico-chemical study

A comprehensive study on the interactions of surface active ionic liquids (SAILs) [C_nmim][Cl], where n = 8, 10, and 12, with a triblock reverse copolymer, 10R5, [(PPO)₈–(PEO)₂₂–(PPO)₈] has been performed using various physico-chemical techniques.

Aggregation of double-tailed ionic liquid 1,3-dioctylimidazolium bromide and the interaction with triblock copolymer F127

The aggregation of ionic liquid-based double-tailed surfactant, 1,3-dioctylimidazolium bromide ([Doim]Br) and its interaction with pluronic copolymer F127 were systematically investigated by nuclear magnetic resonance (NMR), surface tension, dynamic light scattering (DLS), and isothermal titration calorimetry (ITC). It was found that the [Doim]Br aggregates are composed with the alkyl chains embedded in the micellar core and with the imidazolium rings parallel and staggered on the hydrophilic layer of micelles, which was generally different from the single-tailed IL [omim]Br. The hydrogen bonding between protons attached to the imidazolium rings and anion Br(-) was enhanced upon the aggregation of [Doim]Br. The aggregation of F127 was promoted by addition of [Doim]Br, which was more efficient than the single-tailed surfactant. At lower [Doim]Br content, [Doim]Br monomers embedded deeply into F127 micelle core. At higher [Doim]Br concentrations, the F127 micelles were disassociated, and then F127 chains penetrated into [Doim]Br micelle. In addition, the microstructure of F127/[Doim]Br complex can also be tuned by temperature.

Interaction of normal and reverse pluronics (L44 and 10R5) and their mixtures with anionic surfactant sodium N-dodecanoylsarcosinate

Interaction of monomeric normal L44 [(PEO)10(PPO)23(PEO)10]) and reverse 10R5 [(PPO)8(PEO)22(PPO)8] pluronics designated as L and R, respectively, and their mixtures with the anionic surfactant sodium N-dodecanoylsarcosinate (SDDS) in aqueous medium has been studied by tensiometry, conductometry, calorimetry and dynamic light scattering methods. The critical aggregation concentration (CAC), concentration of maximum binding (CS), and the extended critical micelle concentration (CMCe) of SDDS resulted from the interaction have been presented. L has shown the formation of CAC, CS and CMCe, whereas R has shown the absence of CAC but the presence of both CS and CMCe. Micellization of SDDS is an endothermic process whereas the formation of CAC and CMCe is exothermic events, the formation of CS is endothermic. The hydrodynamic diameter (Dh) and zeta potential of L and R, and their SDDS interacted species have been determined. Dh decreased with increasing SDDS concentration for L whereas it was invariant for R. Mixed L and R in varied proportions have been also examined in the solution state to probe into their mutual interaction, and interaction with SDDS. The formation of CAC of their mixtures was absent; CMCe formation was exothermic while that of CS was endothermic like their individuals.

Influence of headgroup on the aggregation and interactional behavior of twin-tailed cationic surfactants with pluronics

The surface tension measurements have been employed to characterize the micellar and interfacial behavior of pure and mixed systems of twin-tailed cationic surfactants: dimethylene bis(decyldimethylammonium bromide) (10-2-10), didecydimethylammonium bromide (DDAB), and 1,3-didecyl-2-methylimidazolium chloride (DDIC) with pluronics P84 and F108 in the aqueous solution. The interactions of each surfactant with both pluronics are found to be nonideal and synergistic except for the mixed system of 10-2-10 + F108, for which interactions are antagonistic and every interaction has been studied on the basis of headgroup disparity. Dynamic light scattering (DLS), zeta (ζ) potential, and small angle neutron scattering (SANS) measurements have been used to determine the influence of the mixing ratio on the morphology of the various mixed aggregates that are formed. Pure DDAB is found to form unilamellar vesicles whereas pure 10-2-10 and DDIC form prolate ellipsoidal micelles. The unilamellar vesicles of DDAB are destructed to yield spherical mixed micelles on addition of pluronics via expansion or contraction of vesicles. However, the pure pluronics and their mixed systems with 10-2-10 and DDIC form charged spherical micelles, and charge is confirmed by thenfractional charge and ζ values. The ζ values of pure surfactants are found to decrease on addition of pluronics, indicating a decrease in surface charge on inclusion of pluronics.

Thermogelling properties of triblock copolymers in the presence of hydrophilic Fe3O4 nanoparticles and surfactants

We investigate the supramolecular structure formed by thermogelation of a triblock polymer in the presence of nanoparticles and surfactant using rheometry and small-angle X-ray scattering (SAXS). The triblock copolymer, nanoparticle, and surfactant used in this study are poly(oxyethylene-oxypropylene-oxyethylene), Pluronic F108, Fe(3)O(4) nanoparticles, and sodium dodecyl surfactant, respectively. Addition of 1-5 wt % of Fe(3)O(4) nanoparticle, of average particle size ~10 nm, in a weak template of F108 (15 wt %) shows a decrease in the onset of gelation temperature and dramatic alteration in the viscoelastic moduli. The nanocomposite samples show a linear viscoelastic regime up to 5% strain. The SAXS measurement shows that the intermicellar spacing of the supramolecular structure of pure F108 is ~16.5 nm, and the supramolecular structure is destroyed when nanoparticles and surfactants are incorporated in it. Further, the addition of anionic surfactant to nanocomposites leads to a dramatic reduction in the viscoelastic properties due to strong electrostatic barrier imparted by the surfactant headgroup that prevents the formation of hexagonally ordered micelles. Our results show that the thermogelation is due to the clustering of nanoparticles into a fractal network rather than a close-packed F108 micelles, in agreement with the recent findings in Pluronic F127-laponite systems.