AbstractIn 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.