Reparation Of High-Strength And Self-Healing Polyurethane Elastomer And Its Application As A Flexible Sensing Substrate

Polyurethane elastomer,as a stretchable substrate,has excellent impact resistance and wear resistance in practical applications,and has a wide application prospect in the field of flexible wearable electronic devices and electronic skin.However,cracks will inevitably occur in the process of using the material,limiting its service life.Although the introduction of dynamic bonds into polyurethane elastomers can give the material self-healing properties,it is difficult to achieve both self-healing and mechanical properties of polyurethane elastomers due to the weak bond strength of dynamic covalent bonds.In this paper,the structure of polyurethane elastomer was designed on the basis of dynamic disulfide bond.DU was introduced into polyurethane network to prepare self-healing at room temperature and recyclable polyurethane elastomer with ultra-high mechanical properties,and TA modified MXene was deposited on its surface to explore its practical application as a multi-functional flexible wearable sensor.Furthermore,the application of disulfide polyurethane elastomer in the field of electronic skin was explored by combining the elastomer with the hydrogel with strong adhesion to form a double-layer composite material.First of all,a room-temperature self-healing and recyclable polyurethane（PU）elastomer with ultrahigh mechanical performances is constructed by synergistically incorporating dynamic disulfide bonds and multiple hydrogen bonds（H-bonds）into PU chain.The introduction of diazolidinyl urea（DU）motifs formed strong H-bonds and branching crosslinking points,improving the robustness of crosslinked structure,and the fast metathesis of aromatic disulfide bonds mainly contributes to the dynamicity of crosslinked network.The resulting PU elastomers exhibit high tensile strength（14.08 MPa）,toughness(64.6 MJ m^-3),superior elastic restorability,outstanding self-healing capability（～81%at room temperature）and multiple recyclability.Furthermore,a wearable sensor based on this elastomer is constructed to monitor different human motions,demonstrating the potential application in wearable electronics.Secondly,A hydrogel with antibacterial properties,excellent biocompatibility and super adhesion with polyurethane elastomers（PU-SS）is constructed by hydrogen bond interactions and hydration,tannic acid,chito-oligosaccharides and Li Cl are combined into a three-dimensional network of polyacrylic hydrogels.Catechol groups of tannic acid（TA）enhance the adhesion properties（16.2 KPa）and antibacterial properties of hydrogels,hydrogen bonding between chito-oligosaccharides（CSO）and polyacrylic acid gives hydrogels high mechanical properties and excellent biocompatibility,and Li Cl gives hydrogels high electrical conductivity（3.06 S/m）and makes the hydrogel/elastomer composites with excellent sensing properties.The composite material with polyurethane as epidermal hydrogel as derma makes it applicable in the field of electronic skin,an electronic skin based on this composite material is constructed to transmit electrical signals while also detecting a person’s health.