Shape transition of magnetic field sensitive polymer gels

D. Szabó, G. Szeghy, M. Zrínyi

Research output: Contribution to journalArticle

177 Citations (Scopus)


Magnetic field sensitive gels, called ferrogels, are chemically cross-linked polymer networks swollen by a ferrofluid. The monodomain magnetic particles, with a typical size of about 10 nm, couple the shape of the polymer gel to the nonuniform external magnetic field. Shape distortion occurs instantaneously and disappears abruptly when an external magnetic field is applied or removed, respectively. This work provides a thermodynamic analysis of shape transition based on the free energy of the swollen network that includes the elasticity of network chains as well as magnetic interactions of finely dispersed solid particles with the external field. It is shown that noncontinuous shape transition is due to a shift of equilibrium state from one local minimum to another one, similar to a first-order phase transition. The discussions presented here may be useful for the design of magnetically active soft polymeric actuators.

Original languageEnglish
Pages (from-to)6541-6548
Number of pages8
Issue number19
Publication statusPublished - Sep 22 1998

ASJC Scopus subject areas

  • Organic Chemistry
  • Polymers and Plastics
  • Inorganic Chemistry
  • Materials Chemistry

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