Biopolymers are new generation polymers which find applications in biomedical field, in food packaging, as edible films etc., due to its unique property of biodegradability and biocompatibility, which is a major concern in case of fossil derived polymers. The application of biopolymers gets limited due to its low mechanical properties. The mechanical properties of these biopolymers however can be enhanced by reinforcing with suitable fillers of nanometer size range, thereby forming nanocomposites. Chitosan (CS) is a polysaccharide which is one of the most extensively used biopolymer in drug delivery, bone tissue engineering etc. Chitosan/Hydroxyapatite (HAP) nanocomposite can be formed by dispersing HAP nanoparticles in chitosan matrix. The mechanical properties of nanocomposites are dependent on the interactions between nanoparticles and polymer matrix. It is thus essential to understand the mechanism between matrix and nanoparticles in order to tailor the mechanical properties for suitable applications. Molecular Dynamics (MD) is one of the possible tools to study the interactions at atomic level. It can also contribute significantly in the prediction of macro level properties. In this work, MD has been applied to study the underlying mechanisms at atomic length scale during the uniaxial deformation process of CS/HAP nanocomposites. The interactions between HAP and CS have been analyzed using radial distribution function, evolution of hydrogen bonding and electrostatic interactions during the deformation process. The initial results indicate an increase in the modulus of elasticity of CS/HAP nanocomposite when compared to pure chitosan for a given strain rate. It is observed that the primary interaction between nanoparticle and polymer matrix is in the form of an electrostatic attraction between the calcium present in HAP and the oxygen in chitosan chains.

Keywords: Nanocomposites, Molecular dynamics, Chitosan, Hydroxyapatite.