Polyacrylate spin-coated surfaces with controllable functionality: Potential biochips for diagnostic devices

Poly methyl methacrylate-co-methacrylic acid (PMMA-co-MAA) polymer compositions have been synthesized through free radical polymerization in different molar ratios of reactants, namely methyl methacrylate (MMA) and methacrylic acid (MAA). Co-polymer surfaces have been developed by spin-coating technique on silicon wafers substrates. The surface morphology of co-polymer coatings have been analyzed with scanning electron microscopy (SEM) and atomic force microscopy (AFM). The chemical composition of co-polymers has been investigated with nuclear magnetic resonance spectroscopy (NMR). Concentration of surface carboxyl groups (-COOH) was determined by UV-Vis titration and the hydrophilicity of the surfaces has been determined by water-in-air contact angle. We demonstrate that the variation of initial molar ratio of MMA and MAA monomers in the free-radical polymerization reaction directly influences surface morphology and the concentration of -COOH groups on the surface. Such surfaces with high degree of control over surface chemistry and properties can be potentially used in biodiagnostic applications.