Effect of plasma pretreatment on adhesion and mechanical properties of UV-curable coatings on plastics

An attempt was made to study the effect of plasma surface activation on the adhesion of UV-curable sol-gel coatings on polycarbonate (PC) and polymethylmethacrylate (PMMA) substrates. The sol was synthesized by the hydrolysis and condensation of a UV-curable silane in combination with Zr-n-propoxide. Coatings deposited by dip coating were cured using UV-radiation followed by thermal curing between 80 degrees C and 130 degrees C. The effect of plasma surface treatment on the wettability of the polymer surface prior to coating deposition was followed up by measuring the water contact angle. The water contact angle on the surface of as-cleaned substrates was 80 degrees +/- 2 degrees and that after plasma treatment was 43 degrees +/- 1 degrees and 50 degrees +/- 2 degrees for PC and PMMA respectively. Adhesion as well as mechanical properties like scratch resistance and taber abrasion resistance were evaluated for coatings deposited over plasma treated and untreated surfaces. (c) 2010 Elsevier B. V. All rights reserved.