New Monofunctional POSS and Its Utilization as Dewetting Additive in Methacrylate Based Free-Standing Films

New polyhedral oligomeric silsesquioxanes (POSS), ((BuSi)-Bu-i)(7)O12SiOSi(Me)(2)CH2(CH2)(n)CH2OC(O)C(CH3)=CH2 bearing one single methacrylate group, were synthesized by hydrosilylation of allylalcohol or 4-penten-1-ol, followed by acylation with methacryloyl chloride. All intermediates and final derivatives were carefully characterized by FTIR, H-1, C-13, and Si-29 solution state NMR, size exclusion chromatography (SEC), MALDI-TOF MS, and powder XRD (including full indexation of the diffraction patterns). In a second step, POSS/methacrylate based films were prepared. For 10 wt % of POSS, phase separation occurs with concomitant POSS crystallization. This behavior is not observed for 2 wt %, but XPS analyses show migration of POSS toward the film-air interface, which led to improved hydrophobic properties of the UV polymerized films with a 30 degrees increase in contact angle.