TY  - JOUR
A1  - Nöchel, Ulrich
A1  - Reddy, Chaganti Srinivasa
A1  - Wang, Ke
A1  - Cui, Jing
A1  - Zizak, Ivo
A1  - Behl, Marc
A1  - Kratz, Karl
A1  - Lendlein, Andreas
T1  - Nanostructural changes in crystallizable controlling units determine the temperature-memory of polymers
T2  - Journal of materials chemistry : A, Materials for energy and sustainability
N2  - Temperature-memory polymers remember the temperature, where they were deformed recently, enabled by broad thermal transitions. In this study, we explored a series of crosslinked poly[ethylene-co-(vinyl acetate)] networks (cPEVAs) comprising crystallizable polyethylene (PE) controlling units exhibiting a pronounced temperature-memory effect (TME) between 16 and 99 degrees C related to a broad melting transition (similar to 100 degrees C). The nanostructural changes in such cPEVAs during programming and activation of the TME were analyzed via in situ X-ray scattering and specific annealing experiments. Different contributions to the mechanism of memorizing high or low deformation temperatures (T-deform) were observed in cPEVA, which can be associated to the average PE crystal sizes. At high deformation temperatures (>50 degrees C), newly formed PE crystals, which are established during cooling when fixing the temporary shape, dominated the TME mechanism. In contrast, at low T-deform (<50 degrees C), corresponding to a cold drawing scenario, the deformation led preferably to a disruption of existing large crystals into smaller ones, which then fix the temporary shape upon cooling. The observed mechanism of memorizing a deformation temperature might enable the prediction of the TME behavior and the knowledge based design of other TMPs with crystallizable controlling units.
Y1  - 2015
UR  - https://publishup.uni-potsdam.de/frontdoor/index/index/docId/39362
SN  - 2050-7488
SN  - 2050-7496
VL  - 3
IS  - 16
SP  - 8284
EP  - 8293
PB  - Royal Society of Chemistry
CY  - Cambridge
ER  -