Carbon Nanoparticle-Loaded Shape Memory Polyurethanes: Design and Functionalization
Shape memory polyurethanes (PUs) have the ability to response to external stimuli such as electricity, heat, light, moisture, pH, etc. Among PUs, segmented PU possesses high recoverable strain, tunable physical properties, wide range of glass transition t
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Carbon Nanoparticle-Loaded Shape Memory Polyurethanes: Design and Functionalization Ayesha Kausar
Abstract Shape memory polyurethanes (PUs) have the ability to response to external stimuli such as electricity, heat, light, moisture, pH, etc. Among PUs, segmented PU possesses high recoverable strain, tunable physical properties, wide range of glass transition temperature and an easily controllable softening phenomenon. Shape memory nanocomposites have been synthesized from PU containing carbon nanoparticles (C NPs) such as fullerene, graphene, multi-walled carbon nanotube, nanodiamond, etc. The surface modification of C NPs can improve the mechanical, shape memory, strength and thermal properties of the nanocomposite. Shape memory PU and nanocomposite have recently been aroused by research interest due their versatile applications. This chapter basically highlights the design of shape memory PU and their C NP-loaded nanocomposites, the principle of shape memory behavior of these polymers and their applications with future directions. Keywords Fullerene · Nanocomposite · Polymer · Stimulus
4.1 Introduction Shape memory polymers are able to recover their initial shape (mechanical properties) after being subjected to external stimuli such as electricity, heat, light, pH (Yan et al. 2012; Yu et al. 2013; Kanu et al. 2019), humidity (Meng and Hu 2010) and pressure (Thakur and Karak 2014). Thermoplastic poly(urethane) (TPU) and segmented poly(urethane) (PU) block copolymers have gained significant importance in this field. These materials have soft and hard segments, which have been shown to be related to shape memory properties (Khosravi et al. 2020). The soft segments (also referred to as reversible phase) are responsible for the plastic characteristics of the mechanical behavior of the material, while the hard segments (also called fixed
A. Kausar (*) National Center for Physics, Quaid-i-Azam University Campus, Islamabad, Pakistan © Springer Nature Switzerland AG 2021 T. J. Gutiérrez (ed.), Reactive and Functional Polymers Volume Three, https://doi.org/10.1007/978-3-030-50457-1_4
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phase) are associated with the elastic regime. In this context, the hard segments act as regions of molecular switches, which are responsible for the recovery of the original shape of the material. Thermo-sensitive shape memory polymers show shape change by thermal stimulation above the glass transition temperature (Tg) or melting temperature (Tm). Thermo-sensitive PU has been used successfully for biomedical devices, coatings and sporting goods (Sun et al. 2011). The shape recovery effect can also be activated by electrovoltage (Liu et al. 2016) With this in mind, electroactive shape memory PUs have been used to manufacture actuators, electronics, sensors and textiles. In addition, PU-based nanocomposites loaded with conducting nanofillers such as carbon black, carbon nanotubes (CNTs), fullerene, nanodiamonds, etc., have demonstrated improved performance compared to the pristine PUs (Meng and Li 2013; Li et al. 201
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