Polyelectrolyte-surfactant Complexes Research Articles

ChemInform Abstract: Self-Assembled Polyelectrolyte-Surfactant Complexes in Nonaqueous Solvents and in the Solid State

The central goal of macromolecular synthesis is preparation of materials with tailored macroscopic properties. With increasing frequency, synthetic strategies not only address the formation of requisite covalent bonds, but also utilize the capability of molecules to self-organize. Self-assembly is defined as spontaneous intermolecular association via noncovalent bonds (e.g., electrostatic interactions, hydrogen bonds, or hydrophobic interactions), resulting in thermodynamically stable, well-defined supramolecular structures with dimensions ranging from 10 nm to 10 μm. Self-organizing systems are widely represented in nature, e.g., double-helical structures of nucleic acids and bilayers of lipids within cell membranes, with organization and intimately linked function. Assembly through noncovalent interactions offers a number of advantages over chemical synthesis involving formation of covalent bonds: it does not require complicated preparative procedures, the reactions are typically fast, and the resulting structures may be capable of reversible adaptive rearrangement in response to changes in environment (e.g., solvent or temperature). Control over organization of synthetic supramolecular structures by tuning the assembly processes opens fascinating possibilities in the manipulation of materials properties on the molecular scale. This may be particularly important for fabrication of multifunctional materials for technological applications where precise control of properties is essential, e.g., electronic devices, microsensors, separation membranes, catalysts, and biomaterials.

Solvent Manipulation of Liquid Crystal Order and Other Properties in Azo-Containing Surfactomesogen/Poly(styrene sulfonate) Complexes

Stoichiometric ionically bonded side-chain polymer complexes of poly(styrene sulfonate) and quaternary ammonium-functionalised azo-containing surfactomesogens were exposed to controlled humidity atmosphere, to organic non-solvents (acetone, THF, ethyl acetate) and to a good solvent (DMF) for the complex. This modifies or increases the packing order, and includes induction of a crystal-like lamellar structure that is amenable to photoisotropisation. The molecular packing order influences photoinduced birefringence relaxation. Conditions for frozen-in morphologies are discussed in the light of higher temperature data. The observed diversity of phase changes upon solvent exposure is comparable to what is observed in surfactant–polyelectrolyte complexes.

Interpolyelectrolyte Complexation in Chloroform

Interpolyelectrolyte complexes (IPECs) were formed in chloroform from complementary polyelectrolyte-surfactant complexes (PESCs), i.e., linear polyelectrolytes whose counterions were substituted by surfactants to dissolve them in the low-polarity organic solvent. The interaction between such complementary PESCs was followed by turbidimetry, (1)H NMR, and dynamic light scattering. The experimental results, together with those from transmission electron microscopy and scanning force microscopy, provide evidence on the formation IPECs in the system. This process is apparently driven by the entropically favorable release of the pairs of the oppositely charged surfactant ions. If the mixing base-molar ratio between the complementary PESCs, Z, is below a certain threshold value, their chloroform mixtures are colloidally stable, containing relatively large aggregates. These aggregates are attributed to particles of the formed IPECs stabilized by the fragments of the excess polymeric component. Otherwise, the mixtures of the PESCs undergo phase separation (most pronounced at Z = 1) with the formation of an insoluble top phase (attributed to insoluble IPEC) and a clear bottom phase enriched with the surfactant counterions. Electron and scanning force micrographs indicate a rather broad size distribution of the soluble macromolecular coassemblies with a close to spherical shape.

Mesostructured silica hybrids from liquid polyelectrolyte–surfactant–aminosilanol complexes

A novel approach involving the use of a pre-hydrolysed aminosilanol to induce the fluidization of solid-like polyelectrolyte–surfactant complexes to produce viscous liquids that can be processed into mesostructured silica hybrids or electrospun fibres is described. Polyelectrolyte–surfactant–aminosilanol (PSA) complexes were prepared in aqueous mixtures of anionic poly(acrylate) (PA), cationic cetylpyridinium (CP) chloride and cationic pre-hydrolysed 3-aminopropyltriethoxysilane (HAPTES). Increasing the concentration of HAPTES in the mixture changed the phase state of the PSA product from a white precipitate to a liquid complex exhibiting Newtonian behaviour. This was attributed to the partial replacement of bound CP by HAPTES molecules at carboxylate sites on the PA chains. Binding studies indicated that the onset of liquid PSA-complex formation occurred at a HAPTES binding level of approximately 0.3. Fluidization of the solid-like PA–CP complexes by addition of HAPTES was exploited for the preparation of polyelectrolyte–surfactant–silica hybrids with hexagonal or lamellar mesostructure via evaporation-induced assembly. The high viscosity of the PSA liquids was also used to prepare mats of polyelectrolyte–surfactant–silica hybrid micro-fibres by direct electrospinning of the liquid complexes.

Interfacial properties of chitin and chitosan based systems

Chitin and chitosan can be modified to obtain amphiphilic systems with controlled structures and architectures. The hydrophile–lipophile balance (HLB, also called hydrophilic–hydrophobic balance) may be modified with respect to different parameters (pH, degrees of substitution of ionic and alkyl groups), and therefore their properties (especially rheological and interfacial) can be adapted to a specific application. The surface activity of ionic derivatives can be improved either by the addition of an oppositely-charged surfactant, which plays the role of counterion by electrostatic interaction (forming a surfactant–polyelectrolyte complex, SPEC), or by N-alkylation. SPECs are found to be more efficient than alkyl derivatives, and the necessary surfactant concentration to reach tensioactive properties is much lower than its critical micellar concentration in the pure solution. The diversity and the control over such structures and architectures make possible their use in numerous domains, strengthening the current interest in these materials.

Polyelectrolyte–surfactant complexes on solid surface

Polyelectrolyte–surfactant complexes have been deposited on hydrophilic silicon substrates by using a horizontal deposition technique. DNA and carboxymethyl cellulose (carboxyMC) were used as short and long polyelectrolyte and dodecyltrimethylammonium bromide (DTAB) was used as water-soluble surfactant. Varying the surfactant concentration, the structural and morphological information have been obtained for these polyelectrolyte–surfactant complexes. Morphology and out-of-plane structures have been obtained by atomic force microscopy and X-ray reflectivity studies. Electron density profiles obtained from the reflectivity study show that DNA–DTAB complexes form lamellar like multilayered structure but carboxyMC–DTAB complexes form coil-like structure. At lower DTAB concentration, these DNA–DTAB and carboxyMC–DTAB complexes form Gibbs layer, whereas at higher surfactant concentration, DTAB molecules themselves form lamellar like multilayered structure that coexists with the structure formed by the complexes.

Comb-like poly(4-vilylpyridinium) salts with dodecylsulfate, sodium bis(2-ethylhexyl) sulfosuccinate and bromide counter ions. Small-angle X-ray scattering and dynamic light scattering study

Poly(4-vinylpyridine) derivatives alkylated with dimethylsulfate, octylbromide and dodecylbromide were synthesized. Bromide anions in the polymer salts were substituted with octylsulfate, dodecylsulfate or bis(2-ethylhexyl)sulfosuccinate (AOT) anions using ion-exchange reactions. The small-angle X-ray scattering (SAXS) studies of the structure of the comb-like polysalts demonstrated their highly-ordered structure. Loading the comb-like polycation with the surfactant anions leads to additional ordering of the polysalts structure. In the case of large AOT anions the transition from lamella to hexagonal structure is observed. Polyelectrolyte – surfactant complexes (PEC) of poly(4-vinyl-1-methylpyridinium) cation with octylsulfate and dodecylsulfate counter ions demonstrate a higher degree of order than the comb-like polymers having a similar chemical structure. The SAXS studies were complemented by dynamic light scattering study of the solutions of the polymers in chloroform. In the solution the comb-like polymers and their complexes with linear surfactants have coil conformations with the size of the coils close to that of the original poly-4-vinylpyridine. The conformations of PECs with octylsulfate and dodecylsulfate counter ions are more unfolded than those of the corresponding comb-like polymers.

Spread films of synthetic polyelectrolyte-surfactant complexes: Dilational viscoelasticity and effect on water evaporation

Data are presented on the dynamic surface properties of films formed from sodium polystyrenesulfonate-dodecyltrimethylammonium bromide (PSS-DTAB) and poly(diallyldimethylammonium chloride)-sodium dodecyl sulfate (PDADMAC-SDS) complexes by the spreading of the above substances onto a water surface from their concentrated solutions. These films are shown to be stable up to surface pressures of 20 mN/m (PSS-DTAB) and 37 mN/m (PDADMAC-SDS). In the latter case, when the limiting surface pressure is reached, microaggregates are formed in the surface layer along with the film dissolution. The surface films in question markedly decelerate water evaporation, and this phenomenon cannot be explained in terms of the classical Goddard model of the structure of films prepared from polyelectrolyte-surfactant complexes and, at the same time, is in good agreement with a recently proposed model that takes into account hydrophobic interactions.

Effect of monovalent salt on the conformation of polyelectrolyte-surfactant complexes

We study the conformation of polyelectrolyte-surfactant complexes in the presence of monovalent salt. A simple model for the formation of these structures is presented in the framework of the Debye-Hückel-Bjerrum-Manning and Flory theories, with the hydrophobic interactions between the hydrocarbon tails of surfactant molecules treated in the spirit of van der Waals theory as an effective attraction. The extension of the polyelectrolyte-surfactant complexes is analyzed as a function of the salt concentration and a discrete conformational transition between a compact globule and an elongated coil is found, in agreement with experimental results for the unfolding transition of a DNA-cationic surfactant complex.

Hierarchical self-organization in polyelectrolyte-surfactant complexes based on heteroarm star block copolyampholytes

Download options Please wait... Article information DOI https://doi.org/10.1039/B817219F Article type Paper Submitted 01 Oct 2008 Accepted 19 Nov 2008 First published 21 Jan 2009 Download Citation Soft Matter, 2009,5, 2371-2377 BibTex EndNote MEDLINE ProCite ReferenceManager RefWorks RIS Permissions Request permissions Hierarchical self-organization in polyelectrolyte-surfactant complexes based on heteroarm star block copolyampholytes M. R. Hammond, C. Li, C. Tsitsilianis and R. Mezzenga, Soft Matter, 2009, 5, 2371 DOI: 10.1039/B817219F To request permission to reproduce material from this article, please go to the Copyright Clearance Center request page. If you are an author contributing to an RSC publication, you do not need to request permission provided correct acknowledgement is given. If you are the author of this article, you do not need to request permission to reproduce figures and diagrams provided correct acknowledgement is given. If you want to reproduce the whole article in a third-party publication (excluding your thesis/dissertation for which permission is not required) please go to the Copyright Clearance Center request page. Read more about how to correctly acknowledge RSC content. Social activity Tweet Share Search articles by author Matthew R. Hammond Chaoxu Li Constantinos Tsitsilianis Raffaele Mezzenga

Interfacial properties of amphiphilic systems on the basis of natural polymers—chitin derivatives

A review of the amphiphilic derivatives of chitin, obtained by covalent grafting of hydrophilic and hydrophobic radicals, is given. It is shown that water-soluble alkylated derivatives of chitin and chitosan, as well as surfactant-polyelectrolyte complexes between oppositely charged surfactants, exhibit interfacial activity, forming structured (gel-like) adsorption layers (AL). Gel formation inside AL of chitin derivatives is characterized by means of interfacial dilational rheometry.

Surfactant-polyelectrolyte complexes on the basis of chitin

The review is devoted to synthesis and study of interfacial properties of electrostatic complexes between oppositely charged chitin derivatives and surfactants, so-called surfactant-polyelectrolyte complexes (SPECs). The ordered nanostructure of insoluble SPEC found by small-angle X-ray scattering (SAXS) looks as a physical gel network formed by micelle-like aggregates interconnected by macro-molecular chains. Viscoelastic properties of such gels were studied by means of the Hertz method and interfacial dilational rheology. A new method based on the effect of diffusion-enhanced gelation at the interface of aqueous solutions of oppositely charged polyelectrolytes and surfactants was developed. This method makes it possible to produce microcapsules containing enzymes, i.e. microreactors for enzymatic catalysis.

Influence of the lyophilizing power of the polymer chain on the relationships in formation of polyelectrolyte-surfactant complexes

Viscometry and turbidimetry were applied to examine the relationships in formation of complexes by poly-1,2-dimethyl-5-vinylpyridinium methyl sulfate, poly-N,N,N,N-trimethyl(methacryloyloxyethyl)ammonium methyl sulfate, and poly[N-benzyl-N,N-dimethyl-N-(methacryloyloxyethyl)]ammonium chloride with sodium dodecyl sulfate.

Polyelectrolyte–surfactant complexes with long range order

Mixtures of carboxymethyl cellulose (CMC) or hydrophobically modified CMC with an oppositely charged surfactant (benzyldimethyltetradecylammonium chloride) in water were prepared. When the global polymer concentration is 0.18% by weight and the surfactant content is high enough, a precipitate with hexagonal order is formed. The precipitate composition shows practically constancy in its water content and a slight diminution in polymer concentration when the global surfactant content is varied between 0.9 and 23 wt%. The lattice parameter in this phase decreases when the polymer/surfactant ratio in the phase increases; this variation is faster with CMC than with the hydrophobically modified CMC. In this way electrostatic and hydrophobic interactions are far from being additive. From the extrapolation to infinite dilution, the global interaction seems to depend on the substitution degree in the polymer. Additionally, the comparison between the radius at the polar–apolar interface in the cylinders and the lattice parameter as a function of polymer/surfactant ratio in the hexagonal phase is compatible with some of the alkyl chains belonging to the hydrophobically modified CMC being present in the aqueous zone.

Flexible polyelectrolyte conformation in the presence of oppositely charged surfactants

Conformational behavior of flexible polyelectrolytes in the presence of monovalent cationic surfactants is examined. A simple model is presented for the formation of polyelectrolyte-surfactant complexes in salt-free solutions in the framework of the Debye-Hückel-Bjerrum-Manning and Flory theories, including explicitly the hydrophobic interactions between the associated surfactant molecules on the polyelectrolyte. The distribution of complexes is calculated as a function of the surfactant concentration and a discrete conformational transition between an elongated coil and a compact globule was found, in agreement with experimental observations.

Ionic Self-Assembled Redox-Active Polyelectrolyte−Ferrocenyl Surfactant Complexes: Mesomorphous Structure and Electrochemical Behavior

Redox-active polyelectrolyte−surfactant complexes (PSC) were prepared via the ionic self-assembly of sodium poly(styrenesulfonate) (PSS) and ferrocenyl surfactant, n-alkyl (ferrocenylmethyl)ammonium bromide (Fcn, n = 8, 12, 16, where n is the carbon number of the alkyl chain), in solution. The PSS−Fcn complex exhibited an ordered lamellar mesomorphous structure with the long period of d = 2.49, 2.94, and 3.74 nm for PSS−Fc8, PSS−Fc12, and PSS−Fc16, respectively. With increasing the length of surfactant alkyl chain, the stacking order was improved. Interestingly, in the solid complex, the ferrocenyl moieties formed H-aggregation showing an increase in the π−π* energy transfer of cyclopentadienes in the ferrocene moieties as known from the blue shift in the UV spectrum. These complexes showed higher thermal stability compared with their components due to the ionic interaction. Cyclic voltammogram (CV) measurements indicated that the electrode process of these redox-active complex films was diffusion-control...

Effect of molecular weight of poly-N-benzyl-N,N-dimethyl-N-methacryloyloxyethylammonium chloride on its complexation with sodium dodecyl sulfate

Complexation of a cationic polyelectrolyte, poly-N-benzyl-N,N-dimethyl-N-methacryloyloxyethylammonium chloride, with an ananionic surfactant, sodium dodecyl sulfate, in aqueous solutions is studied. The effect of the molecular weight of the polymer on phase separation in the system and on the stability, conformation, and surface activity of the polyelectrolyte-surfactant complexes is examined.

Dye flocculation using polyampholytes and polyelectrolyte‐surfactant nanoparticles

AbstractIn this article, we report on the dye flocculation performance of polyampholytes containing hydrophobically modified cationic, hydrophilic nonionic, and anionic monomer units, always with an excess of cationic charges. The results are compared with homopolymers and with those obtained using nonstoichiometric polyelectrolyte–surfactant complex (PSC) dispersions with adjustable surface charge density. The polyampholytes as well as the PSC can successfully remove the dye Celliton Fast Blue (Dispers blue 3). The efficiency of dye separation is mainly influenced by the charge of polymers or complexes, demonstrating that charge neutralization is one flocculation mechanism. However, PSC, which are almost neutral, are also able to remove the dye due to their size and structure. In this case, the degree of dye removal is a little bit better and the so‐called flocculation window is broader as in the case of charge neutralization. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 104: 1342–1349, 2007

The effect of organic additives on the local dynamics of polyelectrolyte-surfactant complexes

The effect of organic additives on the local dynamics of complexes of poly(N-ethyl-4-vinylpyridinium bromide) with sodium dodecyl sulfate is studied with the use of the solubilization of butanol and Triton X-100 as an example. It is shown that, irrespective of the chemical nature of the solubilizate, the addition of organic compounds gives rise to an increase in the local mobility of the micellar phase. In this case, the segmental mobility of the polyelectrolyte in complexes remains unchanged.

Molecular characteristics and hydrodynamic behavior of polyelectrolyte-surfactant complexes in chloroform

Molecular characteristics of polyelectrolyte complexes of the ultrahigh-molecular-weight poly-(N,N-dimethyl-N-benzyl-N-methacryloyloxyethyl)ammonium chloride with oppositely charged surfactants in chloroform were studied by centrifugal sedimentation and viscometry. The effect of oil-soluble surfactants on the hydrodynamic properties of the complexes was examined.