Effect of bio-based monomers on the scratch resistance of acrylate photopolymerizable coatings
ABSTRACT
Photopolymerizable clear coatings based on bio-sourced acrylates, dedicated to the protection of polycarbonate substrates, were studied. The bio-sourced compounds were not based on triglycerides but were smaller, industrially available molecules similar to classical petro-based monomers. Their polymerization kinetics was studied by photo-DSC and was shown to allow high acrylate conversions even at 25 °C. Closely related coatings enriched in alkyl segments, or in monoacrylates to decrease the crosslinking density, were compared. The material composition affects its nanomorphology deduced from X-ray diffraction. Although these changes in composition can slightly shift the mechanical relaxation, it remains wide, and the elastic modulus remains high (>108 Pa) for all the tested materials. Microscratch experiments highlighted the efficiency of all the new coatings in terms of protection against scratches. Incorporating a monoacrylate, particularly isobornyl acrylate, can improve the scratch resistance especially in terms of critical load (up to 175% increase compared with a classical petro-based coating). © 2014 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2015, 53, 379–388




