Designing of antibacterial plastics: thymol release from photocured thymol-doped acrylic resins

Antibacterial thymol-doped plastics can be prepared by photopolymerisation of solutions of thymol in tripropylenglycoldiacrylic monomer. The antibacterial properties of these doped plastics depend on the thymol release rate and this study reports results about the release of thymol from doped resin discs in different media under different conditions. Thymol-doped resin can release thymol in air, even though at a much slower rate than pure thymol in the form of solid powder. In particular. it has been found that the rate of release of thymol in air is mainly dependent on the temperature and on the thymol content in the resin. On the other hand, when a thymol-doped resin is put in contact with liquids, the rate of diffusion of thymol into surrounding liquids depends mainly on the chemical nature of the liquid, other than on the thymol concentration in the resin. In particular, the release is affected by the capability of the liquids to swell the resin and by the plasticizing effect of thymol. The release of thymol can be quantitatively described by a Weibull-type equation up to complete release of thymol.