Isothermal crystallization kinetics as a probe of the preferential electroactive phase nucleation in silver-poly(vinylidene fluoride) nanocomposites: Dependence on nanoparticle size and concentration

Abstract

The effects of the in-situ grown silver nanoparticles on polymorphic crystalline structure and electroactive phase nucleation of isothermally melt crystallized silver-poly(vinylidene fluoride) (Ag-PVDF) nanocomposites have been probed using differential scanning calorimetry and Fourier transformation infrared spectroscopy. Crystallization kinetics data are suitably analyzed using the Avrami theory to evaluate the overall crystallization rate. Ag NPs significantly affect the crystallization rate within the nanocomposites. It is also observed that varying the concentration and size of the nanoparticles, polymorphism in extended chain-crystals can be suitably manipulated. During solution crystallization, Ag nanoparticles act as an effective heterogeneous nucleation agent to induce the formation of β-phase, which increases with both concentration and size of the nanoparticles. Intriguingly, during isothermal melt crystallization, above a certain concentration and size distribution of the nanoparticles, instead of β-phase, significant amount of γ-phase are formed that increases with the crystallization temperature. The observed behavior has been explained in terms of the extent and orientation of the interaction between the negatively charged Ag and the partially positively charge CH2 bonds of PVDF. The equilibrium melting temperatures and the spherulite growth kinetics parameters, estimated from Hoffmen-Week and Lauritzen–Hoffman models also justify the same.