Controlling the Morphogenesis of Needle-Like and Multibranched Structures in Maleic Anhydride Plasma Polymer Thin Films

We report for the first time the formation of spherical and branched structures when polymerizing maleic anhydride under very low power with pulsed plasma polymerization. A factorial experimental design evidenced duty cycle, frequency and their interactions as decisive factors for the formation and growth of these structures. A mechanism involving the decoupling of deposition (nucleation) and diffusion rates of active species was proposed to relate structure formation to processing parameters. While differences in surface chemistry were not detectable by surface spectroscopy (PM-IRRAS, XPS), AFM force measurements on a carefully designed sample evidenced differences in adhesion and thus surface chemistry between the different film morphologies.