Formation and stability of soluble stochiometric polyelectrolyte complexes: Effects of charge density and polyelectrolyte concentration

• Sterically stabilized polyelectrolyte complexes with stoichiometric composition between oppositely charged synthetic polyelectrolytes carrying strong ionic groups and significantly different molecular weights have been prepared. Poly(sodium styrenesulfonate) (NaPSS) was used as polyanion and a range of brush copolymers with various molar ratio (X = 1, 0.75, 0.5, 0.25) of the poly-methacryloxyethyl trimethylammonium chloride poly(METAC) and the nonionic poly (ethylene oxide) methyl ether methacrylate poly(PEO45MEMA) were used as polycations. Formation and stability of PECs have been investigated by dynamic and static light scattering (LS), turbidity and electrophoretic mobility measurements as a function of polyelectrolyte solution concentration and charge density of the cationic polyelectrolyte. The data obtained suggest that the PEO45- rich systems, NaPSS/PEO45MEMA:METAC-25 and NaPSS/PEO45MEMA: METAC-50, form small, water-soluble, molecular complexes having nonspherical shape. The PEO45-poor NaPSS/PEG45MEMA:METAC-75 form turbid colloidal dispersions, whereas insoluble PECs were revealed for the PEO45-free NaPSS/METAC system. The aggregation level of the PEO45-poor systems is mainly controlled by the concentration of the component solutions used for the preparation of PECs, whereas the aggregation of PEO45-rich nanoparticles is prevented by means of steric stabilization. Electrophoretic mobility data indicate a close to charge neutral state of the generated polyelectrolyte complexes.

Nyckelord

Bottle-brush polyelectrolyte

Dynamic light scattering

Electrophoretic mobility

Polyelectrolyte complex

Self-assembled nanoparticles

Static light scattering

Steric stabilization

Turbidity

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