Transparent and mechanically strong hydrogen-bonded polymer complex elastomers with improved self-healability under ambient conditions

Abstract A major challenge in designing self-healing polymeric materials is to combine robust mechanical properties and high healing efficiency. Herein, we report a kind of transparent, hydrogen-bonded polymer complex elastomers with both good mechanical strength and rapid self-healing capability under ambient conditions. Such elastomers were simply fabricated by in situ photoinitiated random copolymerization of acrylic acid (AA) and N-acryloyl-6-aminocaproic acid (A6ACA), in the presence of a linear polyethylene oxide (PEO). By evaporating water molecules from the samples via free drying, the dynamical hydrogen bonding between PEO and poly(A6ACA-co-AA) were substantially formed, which endowed the polymer chains to form physically crosslinked three-dimensional polymer network, as well as the topological chain entanglements. The resulting optically transparent elastomers exhibited both good mechanical strengths (at break) as high as 1.73 MPa, and excellent stretchability that could be stretched up to 24 times their initial length, respectively. Comparing with the elastomers based on PEO and PAA homopolymer without the A6ACA comonomer, the introduction of A6ACA as a comonomer afforded complex elastomers with comparable mechanical strength and, more importantly, significantly improved self-healing efficiency even under ambient conditions, probably due to the significantly decreased glass transition temperature that facilitated chain mobility and reformation of hydrogen bonds. It is therefore believed that the copolymerization strategy offers a practical method to tune the compositions and to tailor the properties of hydrogen-bonded polymer complexes for engineering elastomers with balanced mechanical and self-healing performance under ambient environment for various applications.