The effect of the molecular orientation on the release of antimicrobial substances from uniaxially drawn polymer matrixes

A new method of controlled release of low molecular weight biocides incorporated in polymer matrixes is described. The molecular orientation of uniaxially drawn biocide doped polymer films is suggested as a significant parameter for controlled release monitoring. Triclosan, a well-established widespread antibacterial agent, has been incorporated into high density polyethylene (HDPE) films that have been subsequently uniaxially drawn at different draw ratios. The molecular orientation developed was estimated utilizing polarized mu-Raman spectra. Biocide incorporated polymer films, drawn at different draw ratios, have been immersed in ethanol-water solutions (EtOH) and in physiological saline. The release of Triclosan out of the polymer matrix was probed with UV-Vis absorption spectroscopy for a period of time up to 15 months. In all cases, although the film surface of the drawn samples exposed to the liquid solution was higher than the undrawn one, the relevant release rate from the drawn specimens was lower than the non-stretched samples depending on the molecular orientation developed during the drawing process. A note is made of the fact that no significant molecular orientation relaxation of the polyethylene films has been observed even after such a long time of immersion of the drawn films in the liquid solutions. (c) 2005 Elsevier B.V. All rights reserved.