Thermoresponsive shape-memory polymers

Leng, J. S., Lan, X., Liu, Y. J., Du, S. Y, Huang, W. M., etal. (2008d), Electrical conductivity of thermoresponsive shape-memory polymer with embedded micron sized NI powder chains,H/p/. Phys. Lett., 92,0I4I0I-3. 

Li, S. C., and Tao, L. 2010. Melt rheological and thermoresponsive shape memory properties of HDPE/PA6/POE-g-MAHblends. Polymer—Plastics Technology and Engineering 49 218-222. 

Lendlein et al. demonstrated the possibilities to design thermoresponsive macroscopic self-folding objects using shape-memory polymers based on different poly(e-caprolactone) [12]. At low temperature, the materials are in their temporary shape. The films recover their permanent shape and irreversibly fold by heating, which could be accompanied by a change of transparency. 

Schematic representation of the thermoresponsive behavior of a shape-memory polymer. 7 represents the 7 of the hard phase and 71 represents the 71 of the switching phase. 

Chung S.E., Park C.H., Yu W.R. and KangT.J. (2011),Thermoresponsive shape memory characteristics of polyurethane electrospun web. Journal of Applied Polymer Science, 120(1) pp. 492-500. 

Kaursoin, J., Agrawal, A. K. (2007), Melt spun thermoresponsive shape memory fibers based on polyurethanes Effect of drawing and heat-setting on fiber morphology and properties, J. Appl. Polym. Set, 1(13,2172-82. 

Temperature variations may result in reversible changes in properties such as structural arrangement, size, solubihty, and shape. Many materials designed for biomedical or biotechnology appHcations are confined to a narrow temperature spectrum in order to be effective in a physiological environment. The following thermoresponsive materials are discussed in the next section poly(N-iso-propylacrylamide (PNIPAAm), polymer brushes, and shape-memory polymers. 

Garle A et al (2012) Thermoresponsive semicrystalline poly(c-caprolactone) networks exploiting cross-linking with cinnamoyl moieties to design polymers with tunable shape memory. ACS Appl Mater Interfaces 4(2) 645-657... 

Thermoresponsive self-folding films can be designed using continuous thermal expansion, melting, shape-memory transition or polymers which demonstrate LCST (Low Critical Solution Temperature) behavior in solutions. Kalaitzidou et al. used continuous volume expansion with temperature and demonstrated thermoresponsive rolling-unrolling of polydimethylsiloxane-gold bilayers tubes at 60-70 °C [24a, 24b] which is due to different temperature expansion coefficients. 

The third group includes thermoresponsive polymers. The strategy to apply magnetic induction to these materials allows the development of both implantable and shape-memory devices (Thevenot et al. 2013). 

Abstract This chapter describes polymers that undergo a temperature-induced phase transition in aqueous solution providing an important basis for smart materials. Different types of temperature-responsive polymers, including shape-memory materials, hquid crystalline materials and responsive polymer solutions are briefly introduced. Subsequently this chapter will focus on thermoresponsive polymer solutions. At first, the basic principles of the upper and lower critical temperature polymer phase transitions will be discussed, followed by an overview and discussion of important aspects of various key types of such temperature-responsive polymers. Finally, selected potential apphcations of thermoresponsive polymer solutions will be described. 

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