Wetting behavior of graft copolymer substrate with chemically identical homopolymer films

The wetting behavior of deuterated poly(ethyl acrylate) (dPEA) and polystyrene (PS) homopolymers on the substrates of dPEA-PS graft copolymers with different graft chains (dPEA-g-xPS, x = 1, 3, 5, average number of graft chains) was investigated utilizing scanning force microscopy (SFM). The lateral force and adhesion force measurements of dPEA-g-xPS substrates show that the surface molecular mobility of the dPEA-g-xPS substrate with the dPEA outermost layer decreases with the number of graft chains because of their different aggregation structure. As the number of PS grafts increases, the wetting behavior of dPEA on graft copolymer substrates changes from wetting to partially wetting. The contact angle measurement at the dPEA homopolymer/dPEA-g-xPS substrate interface indicates that the substrate with more PS grafts has a higher interfacial tension with the dPEA homopolymer. The wetting behavior of PS homopolymer on the dPEA-g-xPS substrates depends on the viscosity of the substrate, which is expected to be lower than that of the PS homopolymer. The dewetting velocities of the PS homopolymer increase with the increase of PS grafts in the dPEA-g-xPS graft copolymers.