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

Mechanisms of the Shape Memory Effect in Polymeric Materials

“…Following these concepts, the triple-SME has been realized in a number of polymer systems [54,[110][111][112][113][114][115][116][117]. Although in theory, we can achieve an infinite number of intermediate shapes [109,118], the significance of the SME in each intermediate shape is reduced with the increase of the number of the intermediate shapes.…”

Reduced time as a unified parameter determining fixity and free recovery of shape memory polymers

“…In general, the polymer's shape memory (SM) effect is described and evaluated in a thermo-temporal SM cycle, where the SMP is firstly deformed at a high temperature (usually above the glass transition or melting point) and subsequently frozen upon cooling to fix the programmed temporary shape. When an environmental stimulus is applied, the SMP could either provide recovery stresses or return to their permanent shapes, depending on whether or not the external loads still exist, namely the constrained or free recovery condition [14][15][16][17][18][19][20][21][22][23][24][25][26][27][28][29][30] . Since SMPs can sense the environmental changes and then take reactions in a predetermined sequence with deformation, they are considered as a promising alternative for the future's spontaneous shape changing and tunable components in various applications such as microelectromechanical systems, surface patterning, biomedical devices, aerospace deployable structures and morphing structures [31][32][33][34][35][36][37][38][39] .…”

Shape-memory properties of magnetically active triple-shape nanocomposites based on a grafted polymer network with two crystallizable switching segments

“…To minimize changes in the surface to volume ratio (S/V) during shape recovery and thus ensuring precise control of the temperatures achieved for the nanocomposites during application of an alternating magnetic field, bending experiments were chosen for both thermal and indirect magnetical stimulation according to the method reported in ref. [10]. As it was demonstrated that a triple-shape effect could be achieved for multiphase AB polymer networks programmed by a one-step or two-step SMCP [44], here we want to investigate the influence of different SMCPs on the shapememory properties of polymer network nanocomposites with grafted polymer network architecture.…”

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Shape-memory polymers (SMP) and composites thereof belong to the class of actively moving polymers, which have the capability of storing one (dualshape) [1][2][3][4][5][6], two (triple-shape) [7][8][9][10][11][12][13] or multiple (multiple-shape) [14] stable temporary shapes and recover their original or other temporary shapes when exposed to an external stimulus. The field of SMP research has developed rapidly over the last years [6,[15][16][17][18][19][20][21][22][23][24][25] and it has become apparent that these functional polymers are motivating novel applications.

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“…Non contact initiation of SME was realized by irradiation with infrared light [29][30][31], applying radio-frequency (RF) [32], or an alternating magnetic field [4,10,[33][34][35][36]. The magnetically triggered SME can be characterized by a specific switching magnetic field strength H sw , which needs to be exceeded to induce the shape change [10]. The inductive heating capability of SMP composites is a result of energy absorption by the embedded magnetic particles from the alternating magnetic field, which is transformed into heat.…”