title: Transparent large-strain thermoplastic polyurethane magnetoactive nanocomposites.
abstract: Organically modified superparamagnetic MnFe(2)O(4)/thermoplastic polyurethane elastomer (TPU) nanocomposites (0.1-8 wt %) were prepared by solvent mixing followed by solution casting. Linear aliphatic alkyl chain modification of spherical MnFe(2)O(4) provided compatibility with the TPU containing a butanediol extended polyester polyol-MDI. All MnFe(2)O(4)/TPU nanocomposite films were superparamagnetic and their saturation magnetization, σ(s), increased with increasing MnFe(2)O(4) content. All nanocomposite films exhibited large deformations (>10 mm) under a magneto-static field. This is the first report of large actuation of magnetic nanoparticle nanocomposites at low-loading levels of 0.1 wt % (0.025 vol %). The maximum actuation deformation of the MnFe(2)O(4)/TPU nanocomposite films increased exponentially with increasing nanoparticle concentration. An empirical correlation between the maximum displacement, saturation magnetization, and magnetic nanoparticle loading is proposed. The cyclic deformation actuation of a 6 wt % surface modified MnFe(2)O(4)/TPU, in a low magnetic field 151 < B(y) < 303 Oe, exhibited excellent reproducibility and controllability. MnFe(2)O(4)/TPU nanocomposite films (0.1-2 wt %) were transparent and semitransparent over the wavelengths from 350 to 700 nm.
authors.affiliation: Ohio Aerospace Institute , Cleveland, Ohio, USA. mitra.yoonessi@nasa.gov
authors.forename: Mitra
authors.initials: M
authors.lastname: Yoonessi
authors.forename: John A
authors.initials: JA
authors.lastname: Peck
authors.forename: Justin L
authors.initials: JL
authors.lastname: Bail
authors.forename: Richard B
authors.initials: RB
authors.lastname: Rogers
authors.forename: Bradley A
authors.initials: BA
authors.lastname: Lerch
authors.forename: Michael A
authors.initials: MA
authors.lastname: Meador