Polyelectrolyte-surfactant complexes of poly[3,5-bis(dimethylaminomethyl)-4-hydroxystyrene]-block-poly(ethylene oxide) and sodium dodecyl sulfate: anomalous self-assembly behavior

Surfactant-Mediated Crystallization-Driven Self-Assembly of Crystalline/Ionic Complexed Block Copolymers in Aqueous Solution

A series of crystalline/ionic complexed block copolymers (BCPs) with various compositions have been prepared by sequential reactions. The BCPs with different hydrophilic fractions can self-assemble into various morphologies, such as spindlelike, rodlike, and spherical micelles with different crystallinity of the core. Bis(2-ethylhexyl) sulfosuccinate sodium salt (AOT) is added as a surfactant to induce the morphological transition of BCPs in aqueous media. The introduced AOT can be tightly bound to the cationic units, and a water-insoluble unit in the corona forms, leading to a reduced tethering density. Consequently, morphological variety changing from rods to platelets to fibril to dendrite-like micelles can be observed.

Supramolecular aggregates from polyacrylates and Gd(iii)-containing cationic surfactants as high-relaxivity MRI contrast agents

The assembly behavior of narrowly dispersed poly(sodium acrylate) (PAAS) of different molecular weights with Gd(iii)-containing cationic metallosurfactants (MS) was investigated by DLS, TEM and relaxivity plotting.

Effect of surfactants on the self-assembly of a model elastin-like block corecombinamer: from micelles to an aqueous two-phase system

Recent advances in genetic engineering now allow the synthesis of protein-based block corecombinamers derived from elastin-like peptide sequences with complete control of chemistry and molecular weight, thereby resulting in unique physical and biological properties. The individual blocks of the elastin-like block corecombinamers (ELbcR's) display different phase behaviors in aqueous solution, which leads to the thermally triggered self-assembly of nano-objects ranging from micelles to vesicles. Herein, the interaction of cationic surfactant dodecyl trimethylammonium bromide (DTAB), anionic surfactant dodecyl sodium sulfate (SDS), and nonionic surfactant octyl-β-glucopyranoside (OG) with an ELbcR has been investigated by dynamic light scattering (DLS), the ζ potential and cryo-transmission electron microscopy (cryo-TEM). At 65 °C and neutral pH in aqueous solution, the ELbcR (E50A40) is associated into micelles with a diameter of 150 nm comprising a hydrophobic (A) core and a hydrophilic (E) anionic (from the glutamic acid residues) corona. The size of these self-assemblies can be controlled by adjusting the cosurfactant concentrations. Although the effects of surfactants on the self-assembly behavior of ELbcR's depend on the hydrocarbon chain length and headgroup of the surfactants, a general tendency to increase in size, which in some cases leads to flocculation and a phase-separated state, is observed. These results support the use of surfactants as a highly interesting means of controlling the self-assembly of ELbcR's in aqueous solution as well as their use in drug delivery and purification processes.

Effect of linear nonionic polymer additives on the kinetic stability of dispersions of poly(diallyldimethylammonium chloride)/sodium dodecylsulfate nanoparticles

In this article, the impact of different neutral polymers on the kinetic stability of charge-stabilized poly(diallyldimethylammonium chloride) (PDADMAC)/sodium dodecylsulfate (SDS) colloidal dispersions is analyzed using dynamic light scattering, electrophoretic mobility, turbidity, and coagulation kinetics measurements. Poly(ethyleneoxide) (PEO), poly(vinylpyrrolidone) (PVP), and dextran of comparable molecular masses as well as a higher-molecular-weight dextran sample were tested as nonionic additives. The light scattering and mobility data indicate that the PEO and PVP molecules may adsorb on the surface of the PDADMAC/SDS nanoparticles formed in the presence of excess surfactant. The primary effect of these additives is manifested in enhanced coagulation of the PDADMAC/SDS nanoparticles due to bridging at lower polymer concentrations and depletion flocculation at higher polymer concentrations. These findings are in sharp contrast to the earlier published effect of the same nonionic polymers on the poly(ethyleneimine) (PEI)/SDS colloidal dispersions, which can be sterically stabilized at appropriate PEO or PVP concentrations. However, the adsorption of the investigated dextran samples is negligible on the PDADMAC/SDS nanoparticles. Therefore, dextran molecules may cause only depletion flocculation in the PDADMAC/SDS system in the vicinity of the critical overlap concentration.