Acta Phys. -Chim. Sin. ›› 2011, Vol. 27 ›› Issue (08): 1919-1925.doi: 10.3866/PKU.WHXB20110815

• SOFT MATTER • Previous Articles     Next Articles

Rheological Properties and Gelation of pH-Responsive P(HEMA/MAA) Nano-Microgel Dispersions

SHEN Ying-Hua1, LIU Hui-Min1, LI Guo-Qing1, ZHAI Zhi-Guo1, SHU Xue-Feng2, TAI Xiu-Mei3   

  1. 1. College of Chemistry and Chemical Engineering, Taiyuan University of Technology, Taiyuan 030024, P. R. China;
    2. Institute of Applied Mechanics & Biomedical Engineering, Taiyuan University of Technology, Taiyuan 030024, P. R. China;
    3. China Research Institute of Daily Chemical Industry, Taiyuan 030024, P. R. China
  • Received:2011-03-07 Revised:2011-06-02 Published:2011-07-19
  • Contact: SHEN Ying-Hua E-mail:shenyinghua@tyut.edu.cn
  • Supported by:

    The project was supported by the Natural Science Foundation of Shanxi Province, China (2010011032-2) and Outstanding Innovative Program for Graduates of Shanxi Province, China (20103036).

Abstract:

Poly((2-hydroxyethyl methacrylate)-co-(methacrylic acid)) (P(HEMA/MAA)) microgels with potential application in the restoration of damaged tissue were prepared. The phase transition behavior of P(HEMA/MAA) microgel dispersions at different pH values and concentrations as well as rheological properties of diluent and concentrated dispersions were investigated by tube inversion measurements and rheometry, respectively. The mechanism of the pH-induced physical gel phase transition was discussed. The results indicate that P(HEMA/MAA) microgel dispersions at a given concentration can be transformed into a macroscopic gel for gelation at a physiological pH. The mechanical strength of the P(HEMA-co-MAA) macroscopic gel (nHEMA/nMAA=8/2, pH=7.0) is the best and the elastic modulus (G') value can reach 7.58×103 Pa. The swelling effects of the P(HEMA/MAA) microgel are different under different conditions, which results in a variety of apparent viscosities for the diluent dispersions. We deduce that the swelling behavior of the microgel particles can be divided into three stages from the outer parts of the particles to the inner parts. The gelation transitions of the concentrated dispersions are caused synergistically by space electrostatic interactions and hydrogen bonds of the neighboring microgel particles or between microgel particles and water molecules.

Key words: Gelation, P(HEMA/MAA) microgel, pH-responsive, Concentration of dispersion, Elastic modulus

MSC2000: 

  • O648