The effect of molecular weight of chitosan on the size of chitosan-Cu2+ complex-stabilized sulfur nanoparticles

Chitosan (CS) samples with average molecular weight (Mw) of 80.4, 61.8, and 45.2 kDa were prepared by the heterogeneous degradation of CS using 1% H _2 O _2 solution under ambient conditions. The degree of deacetylation (DD) of the resultant CS was almost unchanged compared with that of the original CS. The sulfur nanoparticles (SNPs) were prepared by acidification of sodium thiosulfate (Na _2 S _2 O _3 ) in a CS-Cu ^2+ complex solution. The influence of Mw CS on the size of SNPs was investigated. The average size of the SNPs/CS-Cu ^2+ complexes measured through Transmission electron microscopy (TEM) images was 25.1, 32.3, and 48.3 nm for using CS with Mw of 80.4, 61.8, and 45.2 kDa, respectively. The obtained SNPs/CS-Cu ^2+ complexes were also characterized by Ultraviolet-visible (UV-Vis), Fourier-transform infrared (FTIR), and x-ray diffraction (XRD) measurements. The synthetic method is favorable for large-scale production. Furthermore, the SNPs/CS-Cu ^2+ complex can be used as an agent for controlling plant disease in agriculture.