Molecular dynamics simulations of the solubility and conformation change of chitosan grafted polyacrylamide: Impact of grafting rate

Zhao W., Zou W., Liu F., Zhou F., ALTUN N. E.

Journal of Molecular Graphics and Modelling, vol.126, 2024 (SCI-Expanded, Scopus) identifier identifier identifier

  • Publication Type: Article / Article
  • Volume: 126
  • Publication Date: 2024
  • Doi Number: 10.1016/j.jmgm.2023.108660
  • Journal Name: Journal of Molecular Graphics and Modelling
  • Journal Indexes: Science Citation Index Expanded (SCI-EXPANDED), Scopus, Academic Search Premier, Applied Science & Technology Source, BIOSIS, Biotechnology Research Abstracts, Chemical Abstracts Core, Chimica, Compendex, Computer & Applied Sciences, INSPEC, MEDLINE
  • Keywords: Chitosan-grafted-polyacrylamide, Conformation, Molecular dynamics simulation, Water solubility
  • Middle East Technical University Affiliated: Yes

Abstract

Graft modification is an effective approach to improve the water solubility and molecular weight of chitosan. This work investigated the effect of grafting rate on water solubility of chitosan-grafted polyacrylamide (Chi-g-PAM) using molecular dynamics simulations. The intramolecular and intermolecular interaction between Chi-g-PAM with the grafting rate of 100%–250% and water together with the conformation change were analyzed by radial distribution function (RDF), radius of gyration, solvation free energy (ΔGSFE), mean square displacement, diffusion coefficient and shear viscosity. The results showed that the intramolecular hydrogen bonding of Chi-g-PAM was the dominant factor affecting its water solubility. While the grafting rate of Chi-g-PAM increased from 100% to 250%, the RDF of Chi-g-PAM decreased from 5.39 to 3.57 between O–H at 2.0 Å and 2.60 to 1.30 between N–H at 2.1 Å. The interaction between Chi-g-PAM and water increased with grafting rate as the absolute value of ΔGSFE for Chi-g-PAM increased from 432.917 kcal/mol to 858.749 kcal/mol. The solubility of Chi-g-PAM in acidic solution was much better than that of Chi-g-PAM in aqueous solution. Our work on the fundamental insights into the effect of grafted molecular structure of chitosan-based copolymer on its solubility will benefit the development of environmentally friendly chitosan-based flocculants.