%0 journal article
%@ 0027-8424
%A Mohr, R.,Kratz, K.,Weigel, T.,Lucka-Gabor, M.,Moneke, M.,Lendlein, A.

%D 2006
%J Proceedings of the National Academy of Sciences of the United States of America: PNAS
%N 10
%P 3540-3545 
%R doi:10.1073/pnas.0600079103
%T Initiation of shape-memory effect by inductive heating of magnetic nanoparticles in thermoplastic polymers
%U https://doi.org/10.1073/pnas.0600079103
10 
%X In shape-memory polymers, changes in shape are mostly induced by heating, and exceeding a specific switching temperature, Tswitch.,If polymers cannot be warmed up by heat transfer using a hot liquid or gaseous medium, noncontact triggering will be required.,In this article, the magnetically induced shape-memory effect of,composites from magnetic nanoparticles and thermoplastic shapememory polymers is introduced. A polyetherurethane (TFX) and a biodegradable multiblock copolymer (PDC) with poly(p-dioxanone) as hard segment and poly(-caprolactone) as soft segment,were investigated as matrix component. Nanoparticles consisting,of an iron(III)oxide core in a silica matrix could be processed into both polymers. A homogeneous particle distribution in TFX could be shown. Compounds have suitable elastic and thermal properties for the shape-memory functionalization. Temporary shapes of TFX compounds were obtained by elongating at increased temperature,and subsequent cooling under constant stress. Cold-drawing of,PDC compounds at 25°C resulted in temporary fixation of the mechanical deformation by 50–60%. The shape-memory effect of,both composite systems could be induced by inductive heating in,an alternating magnetic field (f  258 kHz; H  30 kAm1). The,maximum temperatures achievable by inductive heating in a specific,magnetic field depend on sample geometry and nanoparticle,content. Shape recovery rates of composites resulting from magnetic,triggering are comparable to those obtained by increasing the environmental temperature.