title: Rheological study of physical cross-linked quaternized cellulose hydrogels induced by β-glycerophosphate.
abstract: As a weak base, β-glycerophosphate (β-GP) was used to spontaneously initiate gelation of quaternized cellulose (QC) solutions at body temperature. The QC/β-GP solutions are flowable below or at room temperature but gel rapidly under physiological conditions. In order to clarify the sol-gel transition process of the QC/β-GP systems, the complex was investigated by dynamic viscoelastic measurements. The shear storage modulus (G') and loss modulus (G″) as a function of (1) concentration of β-GP (c(β-GP)), (2) concentration of QC (c(QC)), (3) degree of substitution (DS; i.e., the average number of substituted hydroxyl groups in the anhydroglucose unit) of QC, (4) viscosity-average molecular weight (M(η)) of QC, and (5) solvent medium were studied by the oscillatory rheology. The sol-gel transition temperature of QC/β-GP solutions decreased with an increase of c(QC) and c(β-GP), the M(η) of QC, and a decrease of the DS of QC and pH of the solvent. The sol-gel transition temperature and time could be easily controlled by adjusting the concentrations of QC and β-GP, M(η) and DS of QC, and the solvent medium. Gels formed after heating were irreversible; i.e., after cooling to lower temperature they could not be dissolved to become liquid again. The aggregation and entanglement of QC chains, electrostatic interaction, and hydrogen bonding between QC and β-GP were the main factors responsible for the irreversible sol-gel transition behavior of QC/β-GP systems.
authors.affiliation: Department of Chemistry, Wuhan University, Wuhan 430072, China.
authors.forename: Jun
authors.initials: J
authors.lastname: You
authors.forename: Jinping
authors.initials: J
authors.lastname: Zhou
authors.forename: Qian
authors.initials: Q
authors.lastname: Li
authors.forename: Lina
authors.initials: L
authors.lastname: Zhang
mesh_terms: D002482:Cellulose / Q000737:chemistry*; D005994:Glycerophosphates / Q000737:chemistry*; D020100:Hydrogels; D012212:Rheology; D013696:Temperature; D014783:Viscosity
chemical_list: D005994:Glycerophosphates; D020100:Hydrogels; D002482:Cellulose; C031463:beta-glycerophosphoric acid