Acta Mechanica Solida Sinica

, Volume 25, Issue 5, pp 520–529 | Cite as

A Theoretical Model for Thermal-Sensitive Microgel with PNIPAM Core and Elastic Shell

Article

Abstract

Poly (N-isopropylacrylamide) (PNIPAM) microgels are widely used in drug delivery due to their fast response to temperature. In order to get a better biocompatibility, PNIPAM microgels are typically coated with a layer of biocompatible material, resulting in composite microgels with core-shell structure. In a composite microgel prepared recently, for example, a microsphere of PNIPAM gel is enclosed by a phospholipid membrane, and the composite microgel exhibits a substantial volume transition in response to temperature changes. Here we develop a theoretical model to describe the thermal-responsive behavior of this composite microgel. In particular, we treat the phospholipid membrane as an elastic layer behaving like rubber-like elastomers and adopt the form of the free-energy function for nematic gels (which refer to anther species of thermal-sensitive gels whose behavior has been intensively studied) as that for PNIPAM gels. We show that the thermal-responsive behavior of the composite microgel can be markedly influenced by the membrane. By investigating the state of stress on the interface, we further predict that when the coating membrane is stiff and thin, wrinkles are expected to occur on the outer surface of the composite microgel after the volume transition.

Key words

gel poly (N-isopropylacrylamide) volume transition core-shell structure 

Preview

Unable to display preview. Download preview PDF.

Unable to display preview. Download preview PDF.

References

  1. [1]
    Huang, J. and Wu, Y.X., Effects of pH, salt, surfactant and composition on phase transition of poly (NIPAm/MAA) nanoparticles. Journal of Polymer Science: Part A: Polymer Chemistry, 1999, 37(14), 2667–2676.CrossRefGoogle Scholar
  2. [2]
    Park, T.G., Temperature modulated protein release from pH/temperature-sensitive hydrogels. Biomaterials, 1999, 20(6): 517–521.CrossRefGoogle Scholar
  3. [3]
    Ichikawa, H. and Fukumori, Y., A novel positively thermosensitive controlled-release microcapsule with membrane of nano-sized poly (N-isopropylacrylamide) gel dispersed in ethylcellulose matrix. Journal of Controlled Release, 2000, 63(1–2): 107–119.CrossRefGoogle Scholar
  4. [4]
    Chu, L., Park, S., Yamaguchi, T. and Nakao, S., Preparation of thermo-responsive core-shell microcapsules with a porous membrane and poly (N-isopropylacrylamide) gates. Journal of Membrane Science, 2001, 192(1–2): 27–39.CrossRefGoogle Scholar
  5. [5]
    Hoare, T., Santamaria, J., Goya, G.F., Irusta, S., Lin, D., Lau, S., Padera, R., Langer, R. and Kohane, D.S., A magnetically triggered composite membrane for on-demand drug delivery. Nano Letters, 2009, 9(10): 3651–3657.CrossRefGoogle Scholar
  6. [6]
    Kono, K., Henmi, A., Yamashita, H., Hayashi, H. and Takagishi, T., Improvement of temperature-sensitivity of poly (N-isopropylacrylamide)—modified liposomes. Journal of Controlled Release, 1999, 59(1): 63–75.CrossRefGoogle Scholar
  7. [7]
    Lin, C.L., Chiu, W.Y. and Lee, C.F., Thermal/pH-sensitive core-shell copolymer latex and its potential for targeting drug carrier application. Polymer, 2005, 46: 10092–10101.CrossRefGoogle Scholar
  8. [8]
    Yu, Y., Xie, R., Zhang, M., Li, P., Yang, L., Ju, X. and Chu, L., Monodisperse microspheres with poly (N-isopropylacrylamide) core and poly (2-hydroxyethyl methacrylate) shell. Journal of Colloid and Interface Science, 2010, 346(2): 361–369.CrossRefGoogle Scholar
  9. [9]
    Faivre, M., Campillo, C., Pepin-Donat, B. and Viallat, A., Responsive giant vesicles filled with poly (N-isopropylacrylamide) sols or gels. Progress in Colloid and Polymer Science, 2006, 133: 41–44.CrossRefGoogle Scholar
  10. [10]
    Campillo, C.C., Pepin-Donat, B. and Viallat, A., Responsive viscoelastic giant lipid vesicles filled with a poly (N-isopropylacrylamide) artificial cytoskeleton. Soft Matter, 2007, 3(11): 1421–1427.CrossRefGoogle Scholar
  11. [11]
    Campillo, C.C., Schroder, A.P., Marques, C.M. and Pepin-Donat, B., Volume transition in composite poly (NIPAM)-giant unilamellar vesicles. Soft Matter, 2008, 4(12): 2486–2491.CrossRefGoogle Scholar
  12. [12]
    Campillo, C.C., Schroder, A.P., Marques, C.M. and Pepin-Donat, B., Composite gel-filled giant vesicles: Membrane homogeneity and mechanical properties. Materials Science and Engineering: C, 2009, 29(2): 393–397.CrossRefGoogle Scholar
  13. [13]
    Flory, P.J. and Rehner, J.J., Statistical mechanics of cross-linked polymer networks I: rubberlike elasticity. Journal of Chemical Physics, 1943, 11(11): 512–520.CrossRefGoogle Scholar
  14. [14]
    Hong, W., Zhao, X., Zhou, J. and Suo, Z., A theory of coupled diffusion and large deformation in polymeric gels. Journal of the Mechanics and Physics of Solids, 2008, 56(5): 1779–1793.CrossRefGoogle Scholar
  15. [15]
    Suo, Z., Theory of dielectric elastomers. Acta Mechanica Solida Sinica, 2010, 23(6): 549–578.CrossRefGoogle Scholar
  16. [16]
    Warner, M. and Wang, X.J., Phase equilibria of swollen nematic elastomers. Macromolecules, 1992, 25(1): 445–449.CrossRefGoogle Scholar
  17. [17]
    Fried, E. and Sellers, S., Free-energy density functions for nematic elastomers. Journal of the Mechanics and Physics of Solids, 2004, 52(7): 1671–1689.MathSciNetCrossRefGoogle Scholar
  18. [18]
    Sawa, Y., Urayama, K., Takigawa, T., Desimone, A. and Teresi, L., Thermally driven giant bending of liquid crystal elastomer films with hybrid alignment. Macromolecules, 2010, 43(9): 4362–4369.CrossRefGoogle Scholar
  19. [19]
    Desimone, A. and Teresi, L., Elastic energies for nematic elastomers. The European Physical Journal E: Soft Matter and Biological Physics, 2009, 29(2): 191–204.CrossRefGoogle Scholar
  20. [20]
    Hirokawa, Y. and Tanaka, T., Volume phase transition in a nonionic gel. Journal of Chemical Physics, 1984, 81(12): 6379–6380.CrossRefGoogle Scholar
  21. [21]
    Huang, Z.Y., Hong, W. and Suo, Z., Nonlinear analyses of wrinkles in a film bonded to a compliant substrate. Journal of the Mechanics and Physics of Solids, 2005, 53(9): 2101–2118.MathSciNetCrossRefGoogle Scholar
  22. [22]
    Mei, H., Huang, R., Chung, J.Y., Stafford, C.M. and Yu, H., Buckling modes of elastic thin films on elastic substrates. Applied Physics Letters, 2007, 90(5): 151902–151903.CrossRefGoogle Scholar

Copyright information

© The Chinese Society of Theoretical and Applied Mechanics and Technology 2012

Authors and Affiliations

  1. 1.School of Aerospace Engineering and Applied MechanicsTongji UniversityshanghaiChina

Personalised recommendations