Synthesis And Characterization Of Hydrogen Bond Self-healing Supramolecular Elastomer With Solvent-resistant Capacity

Self-healing is a desirable ability to extend material lifespan when suffers constant stress and strain that would cause unexpected damage.Self-healing materials usually show spontaneous self-mending ability by interactive non-covalent group that was modified on the macromolecular backbones or the ending of oligomers. Hydrogen bond is the most suitable for the synthetization of self-healing materials due to the low bonding energy and convenient modification. However, self-healing materials based on hydrogen-bond interactions are easier to suffer from low mechanical properties and poor solvent-resistance (especially in polar solvents) due to the lack of molecular chain entanglement. In order to overcome this problem, hybrid networks containing covalent and hydrogen bonds were developed. Researches used epoxide (diepoxide and tetraepoxide) as manageable crosslinker to enhance mechanical properties and insolubility by controlling stoichiometries and side reactions, which in turn decreased self-healing behavior. Hence, a self-healing supramolecular elastomer with both solvent-resistance and tunable mechanical properties is desirable.In this paper, sebacic acid, diethylenetriamine, alkali lignin and urea were used as raw materials to design a new reaction system, and produced sebacic-acid/alkali-lignin self-healing elastomers(LSE). FT-IR and XPS results demonstrated that alkali lignin, which contained carboxyl groups, can condense with diethylenetriamine to form covalent bond.NMR results showed that the addition of alkali lignin can help to form more hydrogen bond groups. DSC results demonstrated that LSE materials were a two-phase structure, and the glass transition temperature decreased with the increase of alkali lignin. XRD results showed that crystallization phase of LSE materials gradually vanished with the increase of alkali lignin. Tensile curve showed that LSE materials had good tensile strength and elongation at break, and the mechanical properties can be turned by changing the dosage of alkali lignin.Self-healing tests showed that LSE-3 had the best self-healing ability, and self-healing efficiency of LSE-3 reached 100% after 48 hours. Solubility tests showed that the introduction of alkali lignin endowed LSE materials with solvent-resisitant ability, especially enhenced the insolubility in DMSO. Cytotoxicity tests showed that the materials is non-cytotoxicity,and have potential applications as medical materials.