Abstract
The synthesis and characterization of poly(dimethylsiloxanes) bearing maleimides end-groups (PDMSM) were carried out through imidization of maleic anhydride with three poly(dimethylsiloxanes) diamines of different molecular weights. Self-photopolymerization of PDMSM was studied by Real-Time Fourier Transform infrared spectroscopy (RT-FTIR) and was possible even without photoinitiator (Darocur 1173). The reaction was found to proceed within seconds upon exposure to ultraviolet (UV) radiation to generate highly crosslinked polymer networks. The results indicated that these polymerizations were less sensitive to oxygen inhibition than the radical processes carried out on conventional UV-curable acrylate resins. The thermal and mechanical properties of these resulting materials were studied starting from PDMS precursors with different molecular weights. These materials exhibit a low glass transition temperature (<100 C) and a high degradation temperature (400 C) depending on the density of crosslinking points. These PDMSM are suitable as hydrophobic additives in a coating formulation based on a UV cured polypropylene glycol bismaleimide. Only a very small amount of silicone additives (0.3 wt %) is needed to change the wettability on the surface of the films. The migration of the additive was clearly shown before irradiation by scanning electron microscopy EDX and surface energy measurements.