TY  - JOUR
A1  - Wang, Li
A1  - Razzaq, Muhammad Yasar
A1  - Rudolph, Tobias
A1  - Heuchel, Matthias
A1  - Nöchel, Ulrich
A1  - Mansfeld, Ulrich
A1  - Jiang, Yi
A1  - Gould, Oliver E. C.
A1  - Behl, Marc
A1  - Kratz, Karl
A1  - Lendlein, Andreas
T1  - Reprogrammable, magnetically controlled polymeric nanocomposite actuators
JF  - Material horizons
N2  - Soft robots and devices with the advanced capability to perform adaptive motions similar to that of human beings often have stimuli-sensitive polymeric materials as the key actuating component. The external signals triggering the smart polymers’ actuations can be transmitted either via a direct physical connection between actuator and controlling unit (tethered) or remotely without a connecting wire. However, the vast majority of such polymeric actuator materials are limited to one specific type of motion as their geometrical information is chemically fixed. Here, we present magnetically driven nanocomposite actuators, which can be reversibly reprogrammed to different actuation geometries by a solely physical procedure. Our approach is based on nanocomposite materials comprising spatially segregated crystallizable actuation and geometry determining units. Upon exposure to a specific magnetic field strength the actuators’ geometric memory is erased by the melting of the geometry determining units allowing the implementation of a new actuator shape. The actuation performance of the nanocomposites can be tuned and the technical significance was demonstrated in a multi-cyclic experiment with several hundreds of repetitive free-standing shape shifts without losing performance.
Y1  - 2018
U6  - https://doi.org/10.1039/c8mh00266e
SN  - 2051-6347
SN  - 2051-6355
VL  - 5
IS  - 5
SP  - 861
EP  - 867
PB  - Royal Society of Chemistry
CY  - Cambridge
ER  - 
TY  - JOUR
A1  - Razzaq, Muhammad Yasar
A1  - Behl, Marc
A1  - Heuchel, Matthias
A1  - Lendlein, Andreas
T1  - Matching magnetic heating and thermal actuation for sequential coupling in hybrid composites by design
JF  - Macromolecular rapid communications
N2  - Sequentially coupling two material functions requires matching the output from the first with the input of the second function. Here, magnetic heating controls thermal actuation of a hybrid composite in a challenging system environment causing an elevated level of heat loss. The concept is a hierarchical design consisting of an inner actuator of nanocomposite material, which can be remotely heated by exposure to an alternating magnetic field (AMF) and outer layers of a porous composite system with a closed pore morphology. These porous layers act as heat insulators and as barriers to the surrounding water. By exposure to the AMF, a local bulk temperature of 71 degrees C enables the magnetic actuation of the device, while the temperature of the surrounding water is kept below 50 degrees C. Interestingly, the heat loss during magnetic heating leads to an increase of the water phase (small volume) temperature. The temperature increase is able to sequentially trigger an adjacent thermal actuator attached to the actuator composite. In this way it could be demonstrated how the AMF is able to initiate two kinds of independent actuations, which might be interesting for robotics operating in aqueous environments.
KW  - artificial muscles
KW  - magnetosensitivity
KW  - nanocomposites
KW  - soft actuators
Y1  - 2019
U6  - https://doi.org/10.1002/marc.201900440
SN  - 1022-1336
SN  - 1521-3927
VL  - 41
IS  - 1
PB  - Wiley-VCH
CY  - Weinheim
ER  -