Properties of silver-filled acrylate photopolymer layers prepared by a heterogeneous photocatalytic polymerisation reaction

Crosslinked, silver-filled acrylate photopolymer coatings on polyetheretherketone films were prepared without the aid of molecular photoinitiators by exploiting the photocatalytic activity of a silver-coated titanium dioxide pigment for the initiation of the polymerisation reaction. Because of the strong hydrophilic properties of the photopolymer the layers exhibit an efficient release of silver ions into water. The kinetics of the silver ion release from the coatings is governed by diffusion. The diffusion coefficient of silver ions in the acrylate photopolymer layer was estimated to be about 1 * 10(-13) cm(2)/s which is about eight orders of magnitude lower than the diffusion coefficient of silver ions in water. As expected from the results of the silver ion release tests the acrylate photopolymer layers exhibit an antimicrobial activity. 5 pm thick photopolymer films containing between 2.5 and 7.5 wt.% of the silver-coated titanium dioxide pigment (which corresponds to a silver content between 0.03 and about 0.1 wt.%) eliminate more than 90% of E. coli within 5 h. Within 24 h the bacteria are killed completely. Under the test conditions used only the release of silver ions and not the activity of the titanium dioxide is responsible for the antimicrobial efficacy of the photopolymer layers. (C) 2008 Elsevier B.V. All rights reserved.