TY  - JOUR
A1  - Razzaq, Muhammad Yasar
A1  - Behl, Marc
A1  - Lendlein, Andreas
T1  - Thermally-induced actuation of magnetic nanocomposites based on Oligo(ω-pentadecalactone) and covalently integrated magnetic nanoparticles
JF  - MRS advances: a journal of the Materials Research Society (MRS)
N2  - The incorporation of inorganic particles in a polymer matrix has been established as a method to adjust the mechanical performance of composite materials. We report on the influence of covalent integration of magnetic nanoparticles (MNP) on the actuation behavior and mechanical performance of hybrid nanocomposite (H-NC) based shape-memory polymer actuators (SMPA). The H-NC were synthesized by reacting two types of oligo(ω-pentadecalactone) (OPDL) based precursors with terminal hydroxy groups, a three arm OPDL (3 AOPDL, Mn = 6000 g mol•1−1 ) and an OPDL (Mn =3300 g • mol−1 ) coated magnetite nanoparticle (Ø = 10 ± 2 nm), with a diisocyanate. These H-NC were compared to the homopolymer network regarding the actuation performance, contractual stress (σcontr) as well as thermal and mechanical properties. The melting range of the OPDL crystals (ΔTm,OPDL) was shifted in homo polymer networks from 36 ºC − 76 ºC to 41ºC − 81 °C for H-NC with 9 wt% of MNP content. The actuators were explored by variation of separating temperature (Tsep), which splits the OPDL crystalline domain into actuating and geometry determining segments. Tsep was varied in the melting range of the nanocomposites and the actuation capability and contractual stress (σcontr) of the nanocomposite actuators could be adjusted. The reversible strain (εrev) was decreased from 11 ± 0.3% for homo polymer network to 3.2±0.3% for H-NC9 with 9 wt% of MNP indicating a restraining effect of the MNP on chain mobility. The results show that the performance of H-NCs in terms of thermal and elastic properties can be tailored by MNP content, however for higher reversible actuation, lower MNP contents are preferable.
Y1  - 2018
U6  - https://doi.org/10.1557/adv.2018.613
SN  - 2059-8521
VL  - 3
IS  - 63
SP  - 3783
EP  - 3791
PB  - Cambridge University Press
CY  - New York
ER  - 
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  -