Journal of Polymer Research

, Volume 6, Issue 1, pp 41–49 | Cite as

pH/thermoreversible hydrogels III: Synthesis and swelling behaviors of (N-isopropylacrylamide-co-acrylic acid) copolymeric hydrogels

  • Wen-Fu Lee
  • Chih-Hsuan Shieh


A series of pH-thermoreversible hydrogels exhibiting volume phase transition were synthesized by three degrees of neutralization (DN) of acrylic acid (AA) and N-isopropylacrylamide (NIPAAm). The influence of environmental conditions, such as temperature and pH, on the swelling behavior of these copolymeric gels is investigated in this article. Results show that the negatively charged hydrogels exhibit different equilibrium swelling ratios at different pH values depending on the ionic composition. The pH-sensitivities of these gels also strongly depend on the DN of AA in the copolymeric gels. The results show that the higher the DN, the higher the gel pH-sensitivity. These hydrogels based on a temperature-sensitive hydrogel demonstrate a larger change of equilibrium swelling in aqueous media between a highly solvated, swollen gel state and a collapsed dehydrated network in response to a variation of temperature. On the other hand, a significant phenomenon that was found in the gel swelling kinetics was an overshooting under high temperature conditions. The presented hydrogels were used for release of model drugs that occur at the changes of surrounding conditions, such as temperature and pH, in this study. It was also found that the higher the DN of AA, the higher the gel transition temperature and the larger the release in a high temperature environment and, at the same time, the larger the swelling ratios.


Hydrogel pH-thermoreversibility N-isopropylacrylamide-co-acrylic acid copolymeric gel Swelling ratio 


Unable to display preview. Download preview PDF.

Unable to display preview. Download preview PDF.


  1. 1.
    J. Grignon and A. M. Scallan, J. Appl. Polym. Sci., 25, 2829 (1980).CrossRefGoogle Scholar
  2. 2.
    B. Vazquez, M Gurruchaga, I. Goni, E. Narvarte and J. S. Roman, Polymer, 17, 3327 (1995).Google Scholar
  3. 3.
    K. Kataoka, H. Koyo and T. Tsuruta, Macromolecules, 28, 3336 (1995).CrossRefGoogle Scholar
  4. 4.
    Y. H. Bae, T. Okano and S. W. Kim, J. Polym. Sci., Polym. Phys., 28, 923 (1990).CrossRefGoogle Scholar
  5. 5.
    H. Yu and D. W. Grainger, Macromolecules, 27, 4554 (1994).Google Scholar
  6. 6.
    J. Ricka and T. Tanaka, Macromolecules, 17, 2916 (1984).CrossRefGoogle Scholar
  7. 7.
    S. R. Eisenberg and A. J. Grodzinski, J. Membr. Sci., 19, 173 (1984).CrossRefGoogle Scholar
  8. 8.
    B. Ramaraj and G. Radhakrishnan, J. Appl. Polym. Sci., 52, 837 (1994).CrossRefGoogle Scholar
  9. 9.
    K. Otaka, H. Inomata, M. Konno and S. Saito, Macromolecules, 23, 283 (1992).Google Scholar
  10. 10.
    Y. Hirokawa and T. Tanaka, J. Chem. Phys., 81, 6379 (1984).CrossRefGoogle Scholar
  11. 11.
    W. F. Lee and G. C. Hung, J. Appl. Polym. Sci., 64, 1477 (1997).Google Scholar
  12. 12.
    R. Dinarvand and A. D’Emanuele, J. Control. Rel., 36, 221 (1995).Google Scholar
  13. 13.
    Q. Yan and A. S. Hoffman, Polymer, 36, 887 (1995).Google Scholar
  14. 14.
    Y. H. Bae, T. Okano and S. W. Kim, J. Control. Rel., 9, 271 (1989).Google Scholar
  15. 15.
    T. G. Park and A. S. Hoffman, J. Biomed. Res., 24, 21 (1990).Google Scholar
  16. 16.
    T. G. Park and A. S. Hoffman, Biotech. Bioeng., 35, 152 (1990).Google Scholar
  17. 17.
    Y. Chu, P. P. Varanasi, M. J. Mcglade and S. Varanasi, J. Appl. Polym. Sci., 58, 2161 (1995).CrossRefGoogle Scholar
  18. 18.
    A. R. Khare and N. A. Peppas, Biomaterials, 16, 559 (1995).CrossRefGoogle Scholar
  19. 19.
    J. B. Dressman, G. M. Derbin, G. Ismailos, C. Jarvis, A. Ozturk, B. O. Palsson and T. A. Wheatley, J. Control. Rel., 36, 251 (1995).Google Scholar
  20. 20.
    H. Yu and D. W. Grainger, J. Appl. Polym. Sci., 49, 1553 (1993).Google Scholar
  21. 21.
    W. F. Lee and C. H. Shieh, submitted to J. Appl. Polym. Sci..Google Scholar
  22. 22.
    W. F. Lee and R. J. Wu, J. Appl. Polym. Sci., 62, 1099 (1996).Google Scholar
  23. 23.
    B. G. Kabra, S. H. Gehrke and S. T. Hwang, J. Appl. Polym. Sci., 42, 2409 (1991).CrossRefGoogle Scholar
  24. 24.
    P. J. Flory, Principles of Polymer Chemistry, Cornell Univ Press, Ithaca, New York, 1953.Google Scholar
  25. 25.
    L. Y. Shieh and N. A. Peppas, J. Appl. Polym. Sci., 42, 1579 (1991).CrossRefGoogle Scholar
  26. 26.
    W. F. Lee and C. F. Chen, J. Polymer Research, 5(2), 105 (1998).Google Scholar
  27. 27.
    N. M. Franson and N. A. Peppas, J. Appl. Polym. Sci., 28, 1299 (1983).CrossRefGoogle Scholar
  28. 28.
    R. W. Korsmeyer, E. W. Merrwall and N. A. Peppas, J. Polym. Sci., Polym. Phys. Ed., 24, 409 (1986).Google Scholar
  29. 29.
    M. Yoshida, M. Asano and M. Kumakura, Eur. Polym. J., 25, 1197 (1989).Google Scholar
  30. 30.
    S. H. Yuk, S. H. Cho and H. B. Lee, J. Control. Rel., 37, 69 (1995).Google Scholar
  31. 31.
    T. G. Park and A.S. Hoffman, J. Appl. Polym. Sci., 52, 85(1994).Google Scholar
  32. 32.
    A. S. Hoffman, A. Afrassiabi and L. C. Dong, J. Control. Rel., 4, 213 (1986).Google Scholar
  33. 33.
    L. C. Dong and A. S. Hoffman, J. Control. Rel., 4, 223 (1986).Google Scholar

Copyright information

© Springer Science+Business Media, Inc. 1999

Authors and Affiliations

  1. 1.Department of Chemical EngineeringTatung Institute of TechnologyTaipeiTaiwan, Republic of China

Personalised recommendations