Temperature-induced changes in polymer-based fractal patterns due to Ag metal aggregation

Abstract

The present study throws light on the formation of silver fractal patterns when temperature treatment is given to the chitosan–AgNO3 solution for different temperatures and time periods. Temperature treatment results in both an enhanced degradation of the polymer (i.e., chitosan) and reduction rate of Ag+ ions to the silver particles. Small-sized clusters of silver particles form in the polymeric matrix, which were confirmed by ultraviolet–visible spectroscopy and scanning electron microscopy. Silver clusters aggregate giving different patterns due to the different temperature treatments. Changes in Fourier transform infrared spectra were invoked to explain the reduction of the Ag+ ions and the degradation mechanism of chitosan due to the temperature exposure. Degradation of chitosan due to temperature treatment results in a change in the viscosity. Viscosity measurements were taken by using an Ubbelohde viscometer for the chitosan–AgNO3 system as a function of storage time and temperature treatment time. A decrement in the viscosity was observed in all the cases, which confirms the degradation of chitosan both with and without complexation of salt (AgNO3). The degradation behavior of the polymer in different experimental conditions significantly modifies the aggregation patterns due to silver particles.