Rheological properties of N-[(2-hydroxyl)-propyl-3-trimethyl ammonium] chitosan chloride

N-[(2-hydroxyl)-propyl-3-trimethyl ammonium] chitosan chloride (HTCC) was synthesized using 1-allyl-3-methylimidazole chloride (AmimCl) as a homogeneous green reaction media. The effects of polymer concentration, temperature, cation valence, anion type and concentration of inorganic salt, and degree of substitution (DS) on the rheological properties of HTCC were investigated. The apparent viscosity indicated that HTCC solution was a typical pseudoplastic fluid, which could be described by Ostwald de Waele and Cross-empirical models. The viscoelastic properties showed the formation of gel-like structures. Temperature showed slight effect on the apparent viscosity of HTCC solution, while the DS of HTCC showed remarkable effect on the apparent viscosity. At a low shear rate, the apparent viscosities of HTCC solution increased firstly with an increase of cNaCl from 0 to 40 mmol/L, and then decreased with further increasing cNaCl to 60 mmol/L. At a high shear rate, the opposite trends were observed. The variation of HTCC molecular construction under different inorganic salt conditions was confirmed by scanning electron microscopy, meanwhile, the variation mechanism was proposed.