title: Use of microcapsules as controlled release devices for coatings.
abstract: Biofouling of surfaces is a considerable problem in many industrial sectors and for the public community in general. The problem is usually approached by the use of functional coatings and most of such antifouling coatings rely on the effect of biocides. However, a substantial drawback is the poor control over the release of the biocide as well as its degradation in the paint. Encapsulation of the biocides in microcapsules is a promising approach that may overcome some of the problems associated with the more traditional ways of incorporating the antifouling agent into the formulation. In this review, we summarize more than a decade of microcapsule research from our lab as well as from other groups working on this topic. Focus will be on two coacervation-based encapsulation techniques; the internal phase separation method and the double emulsion method, which together enable the encapsulation of a broad spectrum of biocides with different physicochemical properties. The release of the biocide from core-shell particles and from encapsulated biocides in coatings is treated in detail. The release behaviour is interpreted in terms of the physicochemical properties of the core-shell particle and the coating matrix. In addition, special attention is given to the experimental release methodology and the implementation of proper diffusion models to describe the release. At the end of the review examples of antifouling properties of some coatings against common biofoulers are presented.
authors.affiliation: Department of Chemical and Biological Engineering, Applied Surface Chemistry, Chalmers University of Technology, Göteborg, Sweden; Department of Colloid Chemistry, Max Planck Institute of Colloids and Interfaces, Potsdam, Germany. Electronic address: Markus.AnderssonTrojer@mpikg.mpg.de.
authors.forename: Markus
authors.initials: M
authors.lastname: Andersson Trojer
authors.affiliation: Department of Chemical and Biological Engineering, Applied Surface Chemistry, Chalmers University of Technology, Göteborg, Sweden.
authors.forename: Lars
authors.initials: L
authors.lastname: Nordstierna
authors.affiliation: Department of Chemical and Biological Engineering, Applied Surface Chemistry, Chalmers University of Technology, Göteborg, Sweden.
authors.forename: Jonatan
authors.initials: J
authors.lastname: Bergek
authors.affiliation: Department of Biological and Environmental Sciences, University of Gothenburg, Göteborg, Sweden.
authors.forename: Hans
authors.initials: H
authors.lastname: Blanck
authors.affiliation: Department of Chemical and Biological Engineering, Applied Surface Chemistry, Chalmers University of Technology, Göteborg, Sweden.
authors.forename: Krister
authors.initials: K
authors.lastname: Holmberg
authors.affiliation: Department of Chemical and Biological Engineering, Applied Surface Chemistry, Chalmers University of Technology, Göteborg, Sweden; Ian Wark Research Institute, University of South Australia, Mawson Lakes Campus, Adelaide, South Australia 5095, Australia.
authors.forename: Magnus
authors.initials: M
authors.lastname: Nydén
keywords: Antifouling; Diffusion; Dyes; Exterior wall paint; Marine paint; Sustained release