Shrinkage in UV-curable coatings due to replacement of Van der Waals intermolecular distance by covalent bonds is inevitable. Volume shrinkage occurring in the molding process is a major drawback for various applications, which leads to products warpage, shorten service life and spawn usage limitations as well as economic loss. Recently, expansion monomer and inert component have been widely used to reduce shrinkage in UV-curable coatings. However, these methods are either too complicated in practical uses or can only partly solve the problem and a general and easy method to reduce shrinkage is still lacking until now. Herein we introduce hollow particles with controlled elastic properties prepared by Pickering templates as a general route to solve this problem. The hollow particles not only can be used as reactable filler, but also can reduce the coating shrinkage due to their elasticity and expansionable structures.<br/><br/>In this work, reactable elastic hollow particles with adjustable and controllable wall thickness were fabricated by one-step Pickering emulsion with UV photopolymerization(OPEUP). The oil phase was composed of butyrolactone as solvent, glycidyl methacrylate(GMA) and 1,6-hexanediol diacrylate(HDDA) as reactants, and photoinitiator. After forming the Pickering emulsion stabilized by silica nanoparticles, UV light was applied to initiate the interfacial polymerization within a few seconds. As a result, OPEUP hollow particles with shell thickness from 200 nm to 5 μm can be successfully obtained by controlling the reactant and solvent ratios. The elasticity of the hollow particles can be controlled by adjusting reactant composition. The morphology and structure of the hollow particles can be characterized from SEM images. The nanoindentation measurements indicate that hollow particles obtained show controllable mechanical strength with higher shell thickness. This unique property of the as-prepared hollow particle enables its potential uses in reducing volume shrinkage in UV-curable coatings.

Hollow particles templated from Pickering emulsion and its application in coating shrinkage reduction

256th National Meeting (2018)

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