Room‐temperature self‐healing and reprocessing of Diselenide‐containing waterborne polyurethanes under visible light

Abstract

Realizing environmentally friendly polymers that could heal themselves at room temperature is an important challenge for sustainable societies. Herein, environment-friendly self-healing waterborne polyurethanes (WPUs) containing diselenide groups were synthesized. The healing efficiency could reach up to more than 90% after exposed to visible light for 48 hours and the fractured location was allowed to be healed repeatedly. Meanwhile, a fast room-temperature self-healing could also be achieved in 4 hours with a healing efficiency of~84%. The healing process was a combination of rapid closure of crack surfaces at the beginning due to the rebuilding of hydrogen bonds and gradual restoration of mechanical property derived from diselenide metathesis across the fractured interface. At the same time, room-temperature reprocessing could be also achieved with the aid of external pressure under visible light. Moreover, the prepared diselenide-containing WPUs exhibited excellent emulsion stability. The present work would be hopefully developed into a methodology of design and fabrication of environmentally friendly photo-sensitive polymers with self-healing and reprocessing abilities. covalent bonds, such as Diels-Alder bonds, 16 disulfide, 17,18 imine, 19 Schiff base, 20 diarylbibenzofuranone, 21 trithiocarbonate, 22 and boroxine, 23 and non-covalent bonds, such as hydrogen bond, 24 host-guest interactions, 12 and metal-ligand coordination bonds. 2 Generally, certain external stimulus are required in the intrinsic healing process, such as heat, 16 light, 25 ultrasound, 26 pH change, 27 redox, 28 and water, 29 and a certain time is needed to complete the healing process. However, most of these healing processes occur under harsh conditions, including high temperature, 15 oxygen-free, 22 ultrasound, 26 redox, 28 and pH change, 27,30 which restrict the wide application of these self-healing materials.Compared with the commonly used external stimuli for intrinsic self-healing, light is undoubtedly an attractive one because it is clean, cheap, and readily available, and the healing could be achieved in targeted position and remotely. [31][32][33][34][35] Light sources employed in the healing process including ultraviolet (UV) light, 25 visible light, 31,32 and infrared light. 33 UV light is the Additional Supporting Information may be found in the online version of this article.

Synthesis and characterization of p (N-isopropylacrylamide) hydrogels with tunable swelling behavior using different crosslinkers

“…[11][12][13][14]. The behavior of smart hydrogel can be associated with environmental factors that promote the design and application in many useful bio and environmental system [15][16][17]. Even drug development systems also benefit from hydrogels [18], and many materials from organic and inorganic composites can employed in sensing of external stimuli [19].…”

Synthesis and self‐healing investigation of waterborne polyurethane based on reversible covalent bond

“…The comparisons of the self-healing time and tensile stress between WPU-PA-1.5 film and the reported self-healing polymer materials were exhibited in Figure 7f. 15,18,19,[42][43][44][45][46][47][48] It can be seen from the figure that although tensile stress of our sample is not the highest, the self-healing time was shorter than polymer materials with higher tensile stress. Generally, our sample displays the balance of higher tensile stress and shorter self-healing time, which provided a reference for self-healing materials.…”

Oxime–Urethane Structure‐Based Dynamically Crosslinked Polyurethane with Robust Reprocessing Properties

“…Recently, introducing dynamic covalent bonds and dynamic noncovalent bonds into CCPUs molecular chain can be used to realize reprocessing function, such as oxime-urethane structure, [11] hydrogen bonds, [12] dynamic ionic bonds, [13,14] disulfide, [15,16] diselenide, [17,18] imine, [19] boronic ester bonds, [20] and Diels-Alder (DA). [21,22] Among them, oxime-urethane structure consisting of a carbamate group (-NH-COO-) and an imine bond (C═N), is usually prepared through the reaction between oxime groups and isocyanate groups.…”