Interaction of Low Molecular Weight Poly(diallyldimethylammonium chloride) and Sodium Dodecyl Sulfate in Low Surfactant–Polyelectrolyte Ratio, Salt-Free Solutions

Abstract

Coacervation is widely used in formulations to induce a beneficial character to the formulation but non-equilibrium effects are often manifest. Electrophoretic (eNMR), pulsedgradient spin-echo NMR (PGSE-NMR) and small-angle neutron scattering (SANS) have been used to quantify the interaction between low molecular cationic poly(diallyldimethylammonium chloride) (PDADMAC) and the anionic surfactant sodium dodecylsulphate (SDS) in aqueous solution as a model for the precursor state to such nonequilibrium processes. The NMR data show that within the low surfactant concentration onephase region, an increasing surfactant concentration leads to a reduction in the charge on the polymer and a collapse of its solution conformation, attaining minimum values coincident with the macroscopic phase separation boundary. Interpretation of the scattering data reveals how the rod-like polymer changes over the same surfactant concentration window, with no discernible fingerprint of micellar type aggregates, rather the emergence of disc-like and lamellar structures. At the highest surfactant concentration, the emergence of a weak Bragg peak in both the polymer and surfactant scattering suggest these pre-cursor disc and lamellar structures evolve into paracrystalline stacks which ultimately phase separate. Addition of the non-ionic surfactant hexa(ethylene oxide) dodecyl ether (C12E6) to the system seems to have little effect on the PDADMAC/SDS interaction as determined by NMR, merely displacing the

Viscosity of Polyelectrolyte Surfactant Complexes—The Importance of the Choice of the Polyelectrolyte Seen for the Case of PDADMAC Versus JR 400

“…The difference in SLD needs to be adapted accordingly where SLD PE and SLD solv are the scattering length densities of the pure PE and solvent, respectively. The fitted radius is 0.60(1) nm, similar to that found by Merta et al and Patel et al, and the length is 4.00(9) nm. In order to account for this radius which is much larger than that to be attributed to the pure PDADMAC chain (0.41 nm, for calculations, see eq S3 in the Supporting Information), it is necessary to assume a rather large value of 1.50 for hydration x hyd, PEfree .…”

Charge Modification as a Mechanism for Tunable Properties in Polymer–Surfactant Complexes

“…Oppositely charged PE–surfactant mixtures are known to interact strongly in both the dilute and semidilute regime and, as such, show very interesting aggregation behaviour, which can be fully resolved through the use of contrast variation SANS [ 2 , 10 , 15 , 18 , 19 , 21 , 33 , 34 ]. Here, the nanostructures formed when low concentrations of SDS (C < CMC) are mixed with cat-HEC polymers bearing differing degrees of charge modification are investigated as a way of exploring and controlling Z phase space at fixed C .…”

“…Indeed many of the applications that employ oppositely charged polymer–surfactant systems make use of synthetic polymers such as anionic poly(acrylic acid) or cationic poly(diallyldimethylammonium chloride) [ 2 , 5 , 10 , 11 , 12 , 13 ]. However, more recently, polysaccharides have emerged as an important component in commercially formulated products as a result of their biocompatibility, biodegradability, bioadhesivity, and nontoxicity [ 14 , 15 , 16 , 17 , 18 , 19 , 20 , 21 , 22 , 23 , 24 ].…”

Sex steroid dynamics and mRNA transcript profiles of growth- and development-related genes during embryogenesis following induced follicular maturation in European eel

“…Oppositely charged PE-surfactant mixtures are known to interact strongly in both the dilute and semidilute regime and, as such, show very interesting aggregation behaviour, which can be fully resolved through the use of contrast variation SANS [2,10,15,18,19,21,33,34]. Here, the nanostructures formed when low concentrations of SDS (C SDS < CMC) are mixed with cat-HEC polymers bearing differing degrees of charge modification are investigated as a way of exploring and controlling Z phase space at fixed C polymer .…”

“…As a result of this relative ease of control over such properties, oppositely charged polymer-surfactant mixtures have had great success as formulated products in applications such as, but not limited to, detergency [1][2][3], drug delivery [4][5][6][7], and rheological modifiers [8,9]. Indeed many of the applications that employ oppositely charged polymer-surfactant systems make use of synthetic polymers such as anionic poly(acrylic acid) or cationic poly(diallyldimethylammonium chloride) [2,5,[10][11][12][13]. However, more recently, polysaccharides have emerged as an important component in commercially formulated products as a result of their biocompatibility, biodegradability, bioadhesivity, and nontoxicity [14][15][16][17][18][19][20][21][22][23][24].…”