Atomic force microscopy, scanning electric potential microscopy and contact-angle surface analysis of low-density polyethylene grafted with maleic anhydride

Abstract

Polymers of great commercial use such as polyethylene, polypropylene and polystyrene have had their surface properties modified. Many researchers have recently altered the properties of polymers via grafting reactions. In this work, the surface of low-density polyethylene (LDPE) submitted to grafting with maleic anhydride followed by hydrolysis, chlorination, amination and protonation reactions was analyzed by atomic force microscopy, scanning electric potential microscopy, Fourier transform IR spectroscopy and water contact angle measurements. In different micrographs of the LDPE surface modified by four different processes it was possible to observe that the mountain-shaped structures with a global peak in the virgin polyethylene had become peaky in the grafting steps. It was possible to see that the LDPE surface becomes less rough with the hydrolysis process, going back to values close to those for the virgin polyethylene in the following steps. In scanning electric potential microscopy and topographic micrographs of a chlorinated sample it was possible to observe a correlation between the extent of surface modification and surface topography.