Physically Blended and Chemically Modified Polyurethane Hybrid Nanocoatings Using Polyhedral Oligomeric Silsesquioxane Nano Building Blocks: Surface Studies and Biocompatibility Evaluations

Abstract

Organic–inorganic hybrids are promising materials to use as surface coating. Novel types of hybrids coatings containing polyhedral oligomeric silsesquioxane (POSS) have found interests due to their effects on surface properties. In this study, two types of POSS were added to a two-component polyurethane coating either by physical mixing or chemical linking between POSS and matrix and the affection on the surface properties was investigated. Results showed that addition of an open cage POSS by physical mixing caused segregation of POSS at the surface, while by addition of a POSS containing hydroxyl functional group, it distributed in bulk and surface uniformly. POSS existence on the surface was approved by atomic force microscopy and scanning electron microscopy equipped with energy dispersive X-ray technique. Contact angle measurements showed that the surface free energy of the films decreased from 35.3 mJ/m2 for polyurethane to 13.73 and 11.39 mJ/m2 for chemically and physically processed films, respectively. Biocompatibility of the blank polyurethane and hybrid materials were studied by an MTT assay. Results revealed that cells prefer to have interface with the surface of physically mixed POSS with the matrix in comparison with chemically added POSS.