Agradecimentos: The authors thank L. Gambino for his technical assistance and Christopher Young for his assistance in reviewing and correcting the article. Two of the authors (J.I.A. and O.R.P.) are members of Comisión de Investigaciones Científicas (CIC), Provincia de Buenos Aires (Argentina). One of the authors (P.J.P.) is a postdoctoral fellow of CONICET (Argentina), and one of the authors (P.S.A.) is a doctoral fellow of Agencia Nacional de Promoción Científica y Tecnológica. One of the authors (F.G.) thanks Conselho Nacional de Desenvolvimento Científico e Tecnológico (Brazil) for their support through the INCT (National Institutes for Science and Technology) program Ver menos

Abstract: Polyurethane (PU)/acrylate hybrids with different acrylic contents (10, 30, 50, 70, and 90 wt %) were prepared by the polymerization of acrylic monomers in the presence of preformed PU chains with polymerizable terminal vinyl groups. Films obtained by the casting of polymer dispersions before and after thermal annealing were characterized by dynamic light scattering, Fourier transform infrared spectroscopy, transmission electron microscopy (TEM), TEM electron energy-loss spectroscopy, differential scanning calorimetry, and gel fraction determination. Small-angle X-ray scattering (SAXS), wide-angle Xray scattering, mechanical properties testing, atomic force microscopy, water contact angle testing, Buchholz hardness testing, and roughness testing of the films were also performed. The effects of the acrylic content and thermal treatment on the structure and properties were determined. TEM showed that a core shell morphology was formed during polymerization. When the acrylic content increased, smaller particles without core shell morphologies were observed. TEM energy-loss spectroscopy studies confirmed this observation. Systems with up to 50 wt % acrylic component were homogeneous, as determined by SAXS, before and after thermal annealing. An attempt to incorporate a higher amount of acrylic component led to phase-separated materials with a different morphology and, therefore, different properties. The relationship between the acrylic content and properties did not follow linear behavior Ver menos