THE PREPARATION OF SUB-200NM BIODEGRADABLE COLLOIDAL PARTICLES FROM POLY(BETA-MALIC ACID-CO-BENZYL MALATE) COPOLYMERS AND THEIR SURFACE MODIFICATION WITH POLOXAMER AND POLOXAMINE SURFACTANTS

In this paper a simple precipitation-solvent evaporation method for the preparation of stable spherical sub-200 nm colloids from novel biodegradable poly (beta-malic acid-co-benzyl malate) (PMLABeH) copolymers is described. The particle size and zeta potential were found to be dependent on copolymer composition and concentration of polymer in the organic phase. A range of Poloxamer and Poloxamine polymers was used to modify the surface characteristics of the PMLABeH nanoparticles. The presence of the stabilizers led to a reduction in the surface potential and an increase in surface hydrophilicity of the PMLABeH nanoparticles. Differences observed in the adsorption behaviour of the Poloxamer and Poloxamine stabilizers on the PMLABeH colloids were attributed to an involvement of electrostatic interactions between the carboxyl groups on the surface of the nanoparticles and the tertiary nitrogens in the Poloxamine molecules. A significant difference in the coating thickness, surface hydrophobicity and zeta potential was seen between PMLABeH and polystyrene latexes coated with the Poloxamer and Poloxamine surfactants, suggesting a difference in the coating behaviour for these two particulate systems.