Microscopic Evidence of “Necklace and Bead”-Like Morphology of Polymer–Surfactant Complexes: A Comparative Study on Poly(vinylpyrrolidone)–Sodium Dodecyl Sulfate and Poly(diallyldimethylammonium chloride)–Sodium Dodecyl Sulfate Systems

Abstract

Here, we report the microscopic evidence of "necklace and bead"-like morphology, which has long been the most widely accepted model for polymer-surfactant complexes. The lack of microscopic evidence of the initial complexation between surfactant and polymer has resulted in many contradictory reports in the literature. In this paper, we visualized these initial complexes formed between negatively charged surfactant sodium dodecyl sulfate (SDS) with neutral poly(vinylpyrrolidone) (PVP) and cationic poly(diallyldimethylammonium chloride) (PDADMAC) polymer through photoluminescence (PL) microscopy and atomic force microscopy (AFM) using silicon quantum dot (Si QD) as an external PL marker. It is observed that, for the PVP-SDS system, SDS molecules bind at the hydrophobic sites on the random-coiled PVP chain through their hydrocarbon tails, while for the PDADMAC-SDS system, SDS head groups are associated with the positively charged nitrogen centers of the polymer, where the polymer chain wraps around the surfactant head groups.

Study on the interactions between SDBS/SOE‐60 mixed surfactant and PVP in solution

“…Many fundamental studies have been performed in recent decades to understand the mechanism of surfactant–polymer systems because of their importance in pharmaceuticals, oil recovery processes, and personal care products . Currently, the research focuses mainly on combinations of charged surfactants and neutral polymers . There are two critical concentrations for charged surfactant–neutral polymer complexation: the critical aggregation concentration (cac) and the polymer saturation point (psp).…”

“…[1][2][3] Currently, the research focuses mainly on combinations of charged surfactants and neutral polymers. [4][5][6] There are two critical concentrations for charged surfactant-neutral polymer complexation: the critical aggregation concentration (cac) and the polymer saturation point (psp). The cac is a well-defined concentration at which surfactant molecules begin to associate into polymer chains.…”

Determination of Sodium Dodecyl Sulfate via Turbidimetric Titration with Poly(Diallyldimethylammonium Chloride)

“…The presence of micelles is undoubted because the experimental solution (Hammouda, 2013). At a low amount of PDDA added, electrostatic attraction between cationic macromolecules and surfactant anions leads to formation of ion pairs, resulting in formation of aggregates (Chatterjee et al, 2014;Grządka et al, 2019;Mousseau et al, 2016). The formed aggregates are stabilized with excess of surfactant anions (Fig.…”

“…Among cationic polymers, poly(diallyldimethylammonium chloride) (PDDA, i.e., polyDADMAC) is highly soluble and has a high degree of dissociation over a wide range of pH and ionic strength (Mousseau et al, 2016). PDDA is well known to form strong complexes with lauryl sulfate, lauryl ether sulfate, and laurylbenzenesulfonate (Chatterjee et al, 2014;Guzmán et al, 2016). In the present work, PDDA was examined as a titrant for the quantitative determination of sodium dodecyl sulfate (SDS).…”

Polyvinylpyrrolidone-sodium dodecylsulfate complex is a family of pseudo-polyanions with different charge densities: Evidence from capillary electrophoresis, capillary viscosimetry and conductometry

“…Such a polymer-surfactant association was primarily attributed to hydrophobic interaction between the hydrophobic core of the SDS micelle-like aggregate and the penetrating polymer chain of PEG (or PVP) [15,16], whereas ion-dipole interaction instead of hydrophobic interaction was indicated later by nuclear magnetic resonance results [20,21]. Most recently, hydrophobic interaction between PVP and SDS was reconfirmed by using silicon quantum dots as external photoluminescence markers [22]. Therefore the structure of polymer-surfactant complexes depends on the molecular characteristics of polymers and surfactants [23] and could be driven by ion-dipole, electrostatic and hydrophobic interaction respectively or simultaneously.…”