Incorporation of low molecular weight biocides into polystyrene–divinyl benzene beads with controlled release characteristics

Abstract

Triclosan and phosphonium salt biocides have been separately incorporated into polystyrene–divinylbenzene (PS–DVB) beads by suspension polymerization. Ultraviolet (UV) absorption measurements have been used to monitor the release of these low molecular weight biocides out of the PS–DVB beads immersed in water–ethanol mixtures and in physiological saline. The release of the biocide agents is strongly dependent on either the DVB or/and the antimicrobial composition ratio in the beads. An increase of biocide incorporation in the PS/DVB beads was accompanied by a corresponding enhancement of its concentration in liquid mixtures. On the contrary, higher cross-linking densities hindered the biocide migration out of the beads by diminishing its release rate into either the aqueous ethanol solutions or the natural serum. Moreover, Fourier transform Raman (FT-Raman) spectra and Attenuated Total Reflectance Infrared (ATR-FTIR) measurements of the PS–DVB–Triclosan and PS–DVB–phosphonium salt beads, before and after their immersion in water–ethanol solutions, gave a similar qualitative evidence of the biocide release.