Surface modification of poly(ethylene-co-acrylic acid) with amino-functionalized silica nanoparticles

In this work we studied the possibility to achieve a hybrid-surface through the modification, via a facile wet chemical process, of the surface of films of poly(ethylene-co-acrylic acid) (EAA) with amino-modified silica nanoparticles. Films of EAA were preliminarily activated by the introduction of -COCl groups on their surface. Silica nanoparticles were thereafter covalently bound on the polymeric surface as confirmed by FTIR, ATR-FTIR, XPS, NMR and SEM determinations. The nanoparticles formed a multilayer on the film surface and covered almost uniformly the whole film surface. Direct measurements of superficial amino groups by titration allowed us to detect a concentration of about 18 nmol cm-2. The presence of this uniform layer of nanoparticles bearing polar groups strongly changed the wettability of the material as confirmed by static contact angle measurements that passed from 87° of the neat EAA to about 30° of the amino-functionalized silica nanoparticles modified material.