Synthesis And Characterization Of Self-Healing Supramolecular Elastomer Based On Hydrogen-Bonding Interactions

As emerging developed smart materials, self-healing materials have attracted increasing recent attention. In recent years, one of the main methods to develop self-healing materials is introducing non-covalent bonding groups in the macromolecular chains or small molecule oligomers to obtain supramolecular polymers. Among them, hydrogen-bonding self-healing supramolecular polymers have become the research priorities due to strong orientation, saturation, selectivity and dynamic reversibility of hydrogen bonds. Through the selection of raw materials and the design of the molecular structure, we can obtain the self-healing materials which can achieve self-healing at room temperature without any external help such as healing agents, solvents or other stimulation.In this paper, sebacic acid and citric acid were condensed with diethylenetriamine firstly to synthesize oligomer, and then the obtained product was reacted with urea. Finaly, the hydrogen-bonding self-healing elastomer was obtained after treatment. When the molar ratio of sebacic acid/citric acid is 8:2, a series of products were obtained by varying the urea dosage. Using FT-IR,1H-NMR and 13C-NMR to characterize the preparation process and the final products, the system was full of amide bond, alkyl urea and imidazolinone functional groups, and the mechanism of synthesis reaction was confirmed. GPC results showed that with the increase of urea dosage, the molecular weight was decreased. DSC and XRD results showed that the materials are a two-phase structure, there is low glass transition temperature (Tg) at lower temperature, low urea usage will generate a crystalline phase, and the model of hydrogen bonds crosslinked network was established. In addition, a series of hydrogen-bonding self-healing supramolecular elastomers were synthesized through varying different sebacic acid/citric acid molar ratio. FT-IR was used to following the process of preparation. DSC and XRD analysis confirmed that the materials were a two-phase structure and showed similar Tg at lower temperature. GPC results showed that with the decrease of sebacic acid/citric acid molar ratio, the molecular weight of the materials was decreased.Tensile, creep and stress relaxation analysis showed that the materials have good tensile strength and elongation at break, and exhibit similar creep and stress relaxation behavior with crosslinked elastomer. Self-healing experiments showed that the materials have a dramatic self-healing ability. With the increase of urea dosage or with the decrease molar ratio of sebacic acid/citric acid, the self-healing ability was gradually increased. Healing behavior was observed by SEM, and healing efficiency can up to 100%. Cytotoxicity experiments showed that the materials have potential applications in biomedical materials.Through the above studies, small molecular biological acids could be used to synthesize novel self-healing supramolecular elastomers which have low Tg and show good self-healing ability at room temperature. It provides a new way to develop self-healing materials and extends the application field of self-healing materials.