Actuators polymer chain alignment

Figure 4.9 A scheme showing the change in interactions between a CNTand a polymer chain by the self-heating of a CNT inside a conducting composite nanofiber. (Reprinted with permission from Sensors and Actuators B., Enhanced conductivity of aligned PANi/PEO/MWNT nanofibers by electrospinning by M. K. Shin, Y. J. Kim, 5. I. Kim et a ., 134, 122-126.

It needs to be stressed that the performance of conducting-polymer actuators is heavily dependent upon their conditions of preparation, in that the quality of the films, including factors such as chain alignment and polymer density, can be readily altered as electropolymerization conditions are varied. Several synthetic conditions relevant to conducting-polymer nanostructure are included below. 

Figure 15.6 Polypyrrole chain microstructure before and after processing using stretching or rolling leading to chain alignment in the machine direction (MD). (Reprinted with permission from Polymer, Anisotropic actuation of mechanically textured polypyrrole films by R. Z. Pytel, E. L. Thomas, Y. Chen, and I. W. Hunter, Polymer, 49, 5, 1338-1349. Copyright (2008)...

The photoinduced nanoscale changes at the molecular level induced by light (photoisomerization of the photochromic molecule) are amplified by the cooperative effect of the liquid crystal molecules with the conformation of the polymer chain. The macroscopic movement of these materials, which is characteristic for crosslinked liquid crystalline polymers, strongly correlates with the mesogen alignment. Since such polymer materials can be molded into a variety of shapes and sizes, it is possible to drive components remotely and without direct contact. No wires, electrodes, motors, or gears are necessary. Possible applications are micro actuators and microfiuidic devices. 

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