Shape memory polyurethane polymer

Ahmad, M., Luo, J., Miraftab, M., 2012. Feasibility study of polyurethane shape-memory polymer actuators for pressure bandage application. Science and Technology of Advanced Materials 13, 015006 (7 pp.). 

Tobushi, H., Hashimoto, T., Ito, N., Hayashi, S., Yamada, E., 01/1998. Shape fixity and shape recovery in a film of shape memory polymer of polyurethane series. Journal of Intelligent Material Systems and Structures 9 (2), 127—136. http //dx.doi.org/10.1177/... 

As compared to metallic compounds used as shape memory materials, shape memory polymers have low density, high shape recoverability, easy processability, and low cost. Since the discovery by Mitsubishi in 1988, polyurethane SMPs have attracted a great deal of attention due to their unique properties, such as a wide range of shape recovery temperatures (— 30°C to 70°C) and excellent biocompatibility, besides the usual advantages of plastics. A series of shape memory polyurethanes (SPMUs), prepared from polycaprolactone diols (PCL), 1,4-butanediol (BDO) (chain extender), and 4,4 -diphenylmethane diisocyanate (MDI) or toluene diisocyanate (TDI) have recently been introduced [200—202]. 

Presently, the study of shape memory polyurethane (SMPU) has been widely conducted. For common elastic fibers, the elasticity should be defined as the instant recoverability of the length on release of the deforming stress. The recovery in shape memory fibers is the ability of deformed fibers to recover under external stimulus such as heat or chemicals. In this case, the external stimulus is a must. Figure 3.1 shows the net-points and switches which response to the stimulus (Hu et al., 2012). The elongation of shape memory polymer fiber are a little less than spandex, but mechanical... 

These materials have an obvious application to fusiform aneurysms, which are difficult to treat using coils or liquid embolics due to migration into the parent vessel. Shape memory polymers can potentially remove this limitation since the device is pre-formed to the aneurysm topography. Metcalf et al (2003) investigated a porous polyurethane shape memory polymer as an embolic device for fusiform aneurysms in an animal model. In this study, thick neointimal formation was found over aneurysm necks after a 12-week period. The porous nature of this material may have encouraged cell infiltration and neointimal growth to seal off the aneurysm from the rest of the vasculature (Metcalfe et al,... 

Huang, W. M. 2010. Thermo-moisture responsive polyurethane shape memory polymer for biomedical devices. The Open Medical Device Journal 2 11-19. 

J.S. Leng, W.M. Huang, X. Lan, Y.J. Liu, S.Y. Du, Significantly reducing electrical resistivity by forming conductive Ni chains in a polyurethane shape-memory polymer/ carbon-black composite. Appl. Phys. Lett. 92, 204101 (2008)... 

One of the important developments in, and applications of, textiles is the manufacture of intelligent waterproof breathable fabrics based on shape memory polymers using shape memory polyurethanes. The fabric restricts the loss of body warmth by stopping... 

Abstract This chapter describes vegetable oil-based polymer nanocomposites. It deals with the importance, comparison with conventional composites, classification, materials and methods, characterisation, properties and applications of vegetable oil-based polymer nanocomposites. The chapter also includes a short review of polymer nanocomposites of polyester, polyurethanes and epoxies based on different vegetable oils and nanomaterials. The chapter shows that the formation of suitable vegetable oil-based polymer nanocomposite can be considered to be a means of enhancing many of the desirable properties of such polymers or of obtaining materials with an intrinsically new set of properties which will extend their utility in a variety of advanced applications. Vegetable oil-based shape memory hyperbranched polyurethane nanocomposites can be sited as an exampie of such advanced products. 

Madbouly, S.A. and Lendlein, A. (2012) Degradable polyurethane/soy protein shape-memory polymer blends prepared via environmentally-friendly aqueous dispersions. Macromol. Mater. Eng., 297 (12), 1213-1224. 

Numerous polymers have been proposed as shape-memory polymers (SMPs), and many of them are based on polyurethanes. This is because of the intrinsic versatility of segmented copolyurethane systems. By suitable choice of diisocyanate and macrodiol, a wide variation in properties may be obtained, allowing the possibility of tuning the shape-memory response to suit different applications. Usually they are phase-segregated materials. For example, a dispersed rigid phase (usually based on the diisocyanate) provides physical crosslinks, while the macrodiol provides a soft amorphous phase with low glass transition that provides the trigger temperature for shape recovery [63]. 

These results illustrate the potential of this family of polyurethanes to act as shape-memory polymers, and to be tailored chemically to suit particular practical applications. 

Temperature-dependent permeability to moisture could even be provided by polyurethane-based shape memory polymer (SMP). Better comfort is also provided by moving humidity and sweat away from the surface of the skin, either with hydrophilic linings or by the use of channelled cross-section fibres with reinforced wicking properties. 

Tan et al. smdied the shape memory polymer properties of a series of MMT polyurethane-epoxy composites [87]. The team concluded that tensile strength reached a maximum value at 3 wt% loading while the maximum value of elongation at break was at 2 wt% MMT loading. 

YangBetal (2005) Qualitative separation of the effects of carbon nano-powder and moisture on the glass transition temperature of polyurethane shape memory polymer. Scr Mater... 

---