Issue 17, 2010

Non-contact actuation of triple-shape effect in multiphase polymer network nanocomposites in alternating magnetic field

Abstract

Triple-shape polymers (TSP) can memorize two independent shapes, which are recovered when the temperature is subsequently increased. Certain applications do not allow triggering of the triple-shape effect (TSE) by environmental heating (e.g. potential damaging of surrounding tissue) and therefore require a non-contact activation. Here we explored whether polymer nanocomposites can be designed, which enable non-contact activation of TSE in an alternating magnetic field.

A series of nanocomposites were synthesized by incorporation of silica coated iron(III)oxide nanoparticles into a polymer network matrix containing poly(ε-caprolactone) (PCL) and poly(cyclohexyl methacrylate) (PCHMA) segments. Triple-shape functionalization of the materials was realized by application of different thermomechanical procedures (single or two dual-step), in which samples were deformed by bending to minimize changes in S/V ratio during shape recovery.

For quantification of triple-shape properties inductive heating experiments were conducted in an alternating magnetic field at frequency of f = 258 kHz. By increasing the magnetic field strength H the triple-shape effect was triggered, while the maximum achievable temperature Tmax and the shape change was monitored using an infrared video camera.

Excellent triple-shape properties were achieved for nanocomposites containing 40 wt-% of PCL exhibiting a two-step recovery of shapes B and C, when stimulated by step-wise increasing the magnetic field strength. In this way the TSE could be characterized by two distinct switching magnetic strengths Hsw,1(A → B) and Hsw,2(B → C) corresponding to the switching temperatures determined in cyclic, thermomechanical tensile tests for thermally-induced TSP.

Graphical abstract: Non-contact actuation of triple-shape effect in multiphase polymer network nanocomposites in alternating magnetic field

Supplementary files

Article information

Article type
Paper
Submitted
04 Nov 2009
Accepted
11 Jan 2010
First published
22 Feb 2010

J. Mater. Chem., 2010,20, 3404-3415

Non-contact actuation of triple-shape effect in multiphase polymer network nanocomposites in alternating magnetic field

U. N. Kumar, K. Kratz, W. Wagermaier, M. Behl and A. Lendlein, J. Mater. Chem., 2010, 20, 3404 DOI: 10.1039/B923000A

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