Dynamics of hydrogels with a variable ratio of permanent and transient crosslinks: constitutive model and its molecular interpretation

Jingwen Zhao (1) , Jingyi Guo (2) , Costantino Creton (3, 1) , Chung-Yuen Hui (3, 2) , Tetsuharu Narita (1, 3)

1 SIMM - Sciences et Ingénierie de la Matière Molle (UMR 7615)
2 Cornell University [New York]
3 Hokkaido University [Sapporo, Japan]

Mechanical reinforcement of hydrogels is important to gel science. "Dual crosslink" hydrogels with chemical and transient crosslinks can exhibit improved mechanical properties compared to the corresponding chemically crosslinked gels. Here we use model dual poly(vinyl alcohol) crosslink gels with a variable ratio of chemical and transient crosslinks to study how this ratio affects chain dynamics. Torsion and tensile test results are well described by a constitutive model with only four parameters. The characteristic time of network relaxation (corresponding to the peak of the loss modulus) increases with decreasing transient crosslinker concentration. The characteristic time distribution gradually changes from Maxwell-like to Rouse-like relaxation. These results imply that the Rouse mode of the chains between crosslinks controls transient network dynamics. Our work provides a molecular interpretation of network dynamics and guide optimization of the crosslinking ratios in dual crosslink gels.

Domaines: Polymères; Matière Molle [cond-mat.soft]

Jingwen Zhao, Jingyi Guo, Costantino Creton, Chung-Yuen Hui, Tetsuharu Narita. Dynamics of hydrogels with a variable ratio of permanent and transient crosslinks: constitutive model and its molecular interpretation. Macromolecules, 2022, 55 (9), pp.3550-3562. ⟨10.1021/acs.macromol.1c02440⟩. ⟨hal-03856138⟩