Polyurethane-based shape-memory polymers

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. 

Barikani, M., Zia, K.M., Bhatti, I.A., Zuber, M., Bhatti, H.N. Molecular engineering and properties of chitin based shape memory polyurethane elastomers. Catbohydr. Polym. 74(3), 621-626 (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. 

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]. 

Meng Q, et al. Polycaprolactone-based shape memory segmented polyurethane fiber. J Appl Polym Sci 2007 106 2515-23. 

Meng Q.H., Hu J., Zhu Y, Lu J. and Liu Y. (2007), Polycaprolactone-based shape memory segmented polyurethane fiber. Journal of Applied Polymer Science, 106 pp. 2515-2523. 

Abstract This chapter provides a general introduction to stimuli-responsive shape memory polymers (SMPs). Many SMPs based on different switching mechanisms have been developed and advances in research into SMPs are highlighted. At the end of the chapter, a typical SMP, shape memory polyurethane (SMPU), is introduced because of its tremendous advantages compared with other SMPs in terms of apphcations. 

Other industrial applications include the fabrication of two-part epoxy resins (similar to those commonly found in household maintenance stores) [95-97], These were synthesized using triglycerides and diamines. These resins are often used as adhesives these have also been studied using soybean oil, which provided beneficial properties in terms of fast curing, thermal stability and ease of removal (peel strength) [98], A blend of divinylbenzene/styrene/tung oil mix gave a polyurethane-based material which behaved like a smart polymer with shape memory behaviour [66]. 

H. Deka and N. Karak, Shape-memory property and characterization of epoxy resin modified Mesua ferrea L. seed oii based hyperbranched polyurethane , J Appl Polym Sci, 2010,116,106-15. 

Conductive polymer nanocomposites may also be used in different electrical applications such as the electrodes of batteries or display devices. Linseed oil-based poly(urethane amide)/nanostuctured poly(l-naphthylamine) nanocomposites can be used as antistatic and anticorrosive protective coating materials. Castor oil modified polyurethane/ nanohydroxyapatite nanocomposites have the potential for use in biomedical implants and tissue engineering. Mesua ferrea and sunflower seed oil-based HBPU/silver nanocomposites have been found suitable for use as antibacterial catheters, although more thorough work remains to be done in this field. ° Sunflower oil modified HBPU/silver nanocomposites also have considerable potential as heterogeneous catalysts for the reduction of nitro-compounds to amino compounds. Castor oil-based polyurethane/ epoxy/clay nanocomposites can be used as lubricants to reduce friction and wear. HBPU of castor oil and MWCNT nanocomposites possesses good shape memory properties and therefore could be used in smart materials. ... 

X. (2007) The influence of hard-segments on two-phase structure and shape memory properties of PCL-based segmented polyurethanes. J. Polym. Sci., Part B Polym Phys., 45 (5), 557-570. 

Orthodontics is an area in which polymers are desirable for both their esthetic appeal and shape-memory effect. In 2007, Eliades published an opinion paper on projected future materials for orthodontics and discussed research into polymer-based archwires [67]. In the following year, Jung and Cho demonstrated the use of shape-memory polyurethanes for arch wires [68]. An in vitro dental model was used to test the correction of misaligned teeth and can be seen in Fig. 10. The melt spun polymer, synthesized from 4,4 -methylene bis(phenylisocyanate) and PCL-diol, was stretched to the length required to realign the teeth and attached to stainless... 

Kalita H, Karak N (2013) Bio-based hyperbranched polyurethane/Fe304 nanocomposites as shape memory materials. Polymer Adv Technol 24(9) 819-823... 

Traditionally, chemical catalysts have been used to perform several reactions. By replacing the chemical catalysts with enzymes, final products can proceed in a controlled manner. Enzymatic reactions can be used to upgrade cheap and saturated fats or to add value to commercial fats and oils. Vegetable oil-based polyurethane, polyester, polyether and polyolefin are the four most important classes of polymers, many of which have excellent biocompatibilities and unique properties including shape memory. Many researchers have investigated lipase-catalyzed reactions as an alternative to green processes and as a way to improve the physical properties of final products (Miao et al., 2013). 

W.S. Wang, P. Ping, X.S. Chen, X.B. ling, Polylactide-based polyurethane and its shape-memory behavior, Eur. Polym. J. 42 (June 2006) 1240-1249. 

W. Wang, P. Ping, X. Chen, X. Jing, Shape memory effect of poly(L-lactide)- based polyurethanes with different hard segments, Polym. Int. 56 (2007) 840-846. 

Cao, Q. and P.S. Liu (2006), Structure and mechanical properties of shape memory polyurethane based on hyperbranched polyesters. Polymer Bulletin, 57(6) pp. 889-899. 

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