Dependency of Particle Sizes and Colloidal Stability of Polyelectrolyte Complex Dispersions on Polyanion Structure and Preparation Mode Investigated by Dynamic Light Scattering and Atomic Force Microscopy

Abstract

Polyelectrolyte complex (PEC) dispersions were prepared by controlled mixing of three random copolymers of sodium 2-acrylamido-2-methylpropanesulfonate (AMPS) with either t-butyl acrylamide (TBA) [P(AMPS54-co-TBA46) and P(AMPS37-co-TBA63)] or methyl methacrylate (MM) [P(AMPS52-co-MM48)] with an ionene-type polycation, containing 95 mol % N,N-dimethyl-2-hydroxypropyleneammonium chloride repeat units (PCA5), with their structural characteristics being deeply investigated by dynamic light scattering (DLS) and atomic force microscopy (AFM). Shape, size, and polydispersity of the PEC dispersions were directly observed by AFM as a function of polyanion structure, the ratio between charges, n-/n+, and the titrant addition rate (TAR). The particle sizes increased and the colloidal stability decreased with the increase of the nonionic comonomer content and with the decrease of TAR. It was demonstrated that the medium particle sizes of the complex nanoparticles adsorbed on silicon wafers measured by AFM, in the dry state, were close but always lower than those measured by DLS, both before and after the complex stoichiometry.

Novel Electrospun Nanofibers Composed of Polyelectrolyte Complexes

“…The PECs of chitosan attract attention due to the possibility of tuning the pH sensitive behavior of the prepared materials by changing the nature of the polyacid and the medium conditions (pH, presence of low molecular weight salt) 15, 16. It is known that, depending on the conditions, the preparation of macro‐, micro‐ and nanosized PEC‐based materials is feasible 15, 17, 18. Composite fibers of PEC chitosan/poly(acrylic acid) (PAA) with average diameters of 40–100 µm have been prepared using polyion complex formation between chitosan and PAA at the interface of chitosan and PAA aqueous solutions 19.…”

Influence of the Hydrophobicity of Polyelectrolytes on Polyelectrolyte Complex Formation and Complex Particle Structure and Shape

“…Mihai et al [7] investigated, amongst other factors, the size and shape of polyelectrolyte complexes of random copolymers of sodium 2-acrylamido-2-methylpropanesulfonate with either t-butyl acrylamide or methyl methacrylate with an ionene-type polycation by dynamic light scattering and AFM. It was found, that the mean particle sizes of the complex nanoparticles, measured by AFM, were close but always lower than those measured by DLS.…”

New polyelectrolyte complex particles as colloidal dispersions based on weak synthetic and/or natural polyelectrolytes

“…A very important characteristic of the PECs as colloidal dispersion is their colloidal stability. Storage colloidal stability of PECs is very sensitive to the structure of the complementary polyions, to the molar ratio between charges, i.e., the complex is closer or further to the molar ratio (n -/n + ) n , to the polyions addition order, especially when the complementarities of oppositely charged polyions is disturbed by their structure, and very much to the titrant addition rate, as it was previously demonstrated for PECs prepared with strong polyanions [31][32][33]. Therefore, the particle sizes, D h , measured after 24 h from preparation were compared with those measured after two weeks of storage at room temperature (~22°C), without stirring (data not shown here).…”

“…The polyanion solution was added dropwise to the polycation solution, under magnetic stirring. A constant addition rate of 3.8 ml polyanion/ (ml polycation"h) was used as optimum addition rate, taking into account the complex morphology and the preparation speed, according to our previous investigations on the formation of PECs as colloidal dispersion from synthetic polycations and polyanions [30][31][32][33]. After mixing, the formed dispersions were stirred 60 min and were characterized after 24 h, if other conditions were not specified.…”

“…Our previous studies dealt with the preparation of PECs nanoparticles as stable colloidal dispersions using strong synthetic polyanions and synthetic or natural (CS) polycations. Also, the factors (polyions structure and molar mass, molar ratio between charges, addition order, titrant addition rate) which influence particles size, morphology, and storage stability were investigated [30][31][32][33]. This study aims to obtain PECs as colloidal dispersion using some weak polyelectrolytes: CS and poly(allylamine hidrochloride) (PAH) as polycations and poly(acrylic acid) (PAA) and poly(2-acrylamido-2-methylpropanesulfonic acid -co -acrylic acid) (PAMP-SAA) as polyanions.…”