Effect of Solvents on the Physical and Structural Parameters of Nano Biopolymer

Abstract Functionalized polymers, especially in the nano scale, have a wide range of applications. In this sense, chitosan was prepared in our lab via the deacetylation of chitin obtained from shrimp. The molecular structure of the prepared chitosan was investigated by FTIR which confirmed that it is similar to commercial chitosan. The first step in the functionalization of chitosan for further applications is to dissolve it. Consequently, a DFT:B3LYP/3-21g* model was utilized to study the effect of different solvents on structural and physical properties of chitosan. Total dipole moment (TDM), HOMO/LUMO band gap energy, and molecular electrostatic potential (MESP) were used as physical descriptors to follow up the effect of solvation on nano chitosan. Results indicated that solvation increased the reactivity of chitosan in terms of TDM, HOMO/LUMO band gap energy and MESP. Also, solvation resulted in slight changes in the structural parameters. For experimental verification of the obtained theoretical results, chitosan was dissolved in different solvents then the FTIR spectrum of each solution was recoded and compared with raw (undissolved) chitosan. Results demonstrated no change in the molecular structure under the effect of solvation.