Exploration of the nature of a unique natural polymer-based thermosensitive hydrogel.
The chitosan (CS)/β-glycerol phosphate (GP) system is a heat induced gelling system with a promising potential application, such as an injectable biomedical material. Unlike most thermosensitive gelling systems, the CS/GP system is only partially reversible. That is once the hydrogel is fully matured, it only softens but cannot go back to its initial liquid state when cooled down. Here, we perform both the small and large amplitude oscillatory shear (SAOS and LAOS) tests on the fully matured CS/GP hydrogel samples at a variety of temperatures within the cooling process. The purpose of such tests is to investigate the structural change of the hydrogel network and thus to understand the possible gelation mechanism of this unique thermosensitive hydrogel. From the LAOS results and the further analysis with the Chebyshev expansion method, it shows that the CS/GP hydrogel is composed of a colloidal network dominated by hydrophobic interactions at high temperature, and gradually turns into a flexible network dominated by hydrogen bonding when the temperature goes down. Therefore, we may conclude that LOAS is a powerful tool to study the nonlinear behaviour of a polymer system that is closely related to its structure, and as a practical example, we achieve a clearer vision on the gelation mechanism of the unique CS/GP thermosensitive hydrogel on the basis of considerable previous studies and assumptions in this laboratory and other research groups.
State Key Laboratory of Molecular Engineering of Polymers, Collaborative Innovation Center of Polymers and Polymer Composite Materials, Department of Macromolecular Science, Laboratory of Advanced Materials, Fudan University, Shanghai, 200433, People's Republic of China. chenx@fudan.edu.cn.
Shanling
S
Lu
Research Centre for Analysis and Measurement, Fudan University, Shanghai 200433, People's Republic of China.
Yuhong
Y
Yang
State Key Laboratory of Molecular Engineering of Polymers, Collaborative Innovation Center of Polymers and Polymer Composite Materials, Department of Macromolecular Science, Laboratory of Advanced Materials, Fudan University, Shanghai, 200433, People's Republic of China. chenx@fudan.edu.cn.
Jinrong
J
Yao
State Key Laboratory of Molecular Engineering of Polymers, Collaborative Innovation Center of Polymers and Polymer Composite Materials, Department of Macromolecular Science, Laboratory of Advanced Materials, Fudan University, Shanghai, 200433, People's Republic of China. chenx@fudan.edu.cn.
Zhengzhong
Z
Shao
State Key Laboratory of Molecular Engineering of Polymers, Collaborative Innovation Center of Polymers and Polymer Composite Materials, Department of Macromolecular Science, Laboratory of Advanced Materials, Fudan University, Shanghai, 200433, People's Republic of China. chenx@fudan.edu.cn.
Xin
X
Chen
D048271:Chitosan / Q000737:chemistry*; D005994:Glycerophosphates / Q000737:chemistry*; D020136:Hydrogel, Polyethylene Glycol Dimethacrylate / Q000737:chemistry*; D012212:Rheology; D013696:Temperature
D005994:Glycerophosphates; D020136:Hydrogel, Polyethylene Glycol Dimethacrylate; D048271:Chitosan; C031463:beta-glycerophosphoric acid