Nanoscale viscoelasticity characterization of engineered organometallic nanocomposite thin films for biomedical applications

Abstract

This work is focused on nanoscale viscoelastic properties characterization of gold nanoparticles (AuNPs) reinforced chitosan nanocomposites using nanoindentation. Chitosan nanocomposite films reinforced with gold nanoparticles concentration (w/v) up to 0.25 mg/ml in chitosan were prepared via a solution evaporation technique. Creep and stress relaxation responses were modeled using the generalized Voigt model and the generalized Maxwell model, respectively. Nanoindentation experimental data were analyzed using these models to obtain model constants. Both displacement- and load-controlled ramp functions were used to indent the samples with a 100 µm conospherical indenter tip. The moduli increased with an increase in AuNPs concentration in chitosan. The plasticity index increased with an increase in AuNPs concentration indicating that the deformation became more plastic with an increase in the filler. The results also show the time-dependent viscous response of the nanocomposite is mainly governed by the response of the matrix because the characteristic time scales of the nanocomposite films are independent of the AuNPs concentration.