Low Free Surfaces from Polyurethane/Nanoteflon Composites

M.E. PENOFF; P.E. MONTEMARTINI; P.A. OYANGUREN; P.J. PERUZZO; P.S. ANBINDER; J.I. AMALVY

Viña del Mar, Chile

Congreso; Archipol '07. IV Argentine-Chilean Polymer Symposium. VIII Argentine Polymer Symposium. VIII Chilean Symposium of Polymer Chemistry and Physical Chemistry; 2007

Universidad de Chile y Pontificia Universidad Católica de Chile,

Fluorinated materials are well known for having low surface free energy that makes them water- and oil-repellent. These properties make them very useful as protective coatings like antifouling and antigraffiti paints. On the other hand, the incorporation of fluorine into polyurethane matrixes introduces changes in the final properties such as chemical, thermal, hydrolytic and oxidative stability. It is posible to take an advantage of the fluorinated species migration. In this work we synthesize polyurethane dispersions with different content of Teflon® nanoparticles. Films obtained from dispersions were characterized by contact angle, DSC, SEM, dielectric and friction coefficients determinations. Contact angle results show an increase with nanoparticles content compared to pure polyurethane, reaching a maximum value for 20 wt. % PTFE. According to Cassie´s equation relating contact angles measured on surfaces of a binary mixture to fractional area occupied and intrinsic contact angles of the two pure componentsit, it can be estimated that the surface area fraction occupied by the PTFE nanoparticles at 20 wt.% is ~ 66 %. The dielectric constant decreases as nanoparticles content increases following approximately a mixing law  except for samples containing 20 wt. % where a local minimum is found.