Smart transparent polyamide elastomer for protective coating

The increasing demand for transparent and flexible materials to protect foldable smartphones and curved displays has revealed the limitations of traditional transparent polymer materials such as polycarbonate (PC) and polymethyl methacrylate (PMMA). These materials are prone to cracking after bending or folding and becoming opaque after scratch, thereby compromising the using feeling of flexible screens. As a result, they struggle to simultaneously possess both transparent and flexible characteristics for a long using time. To meet the diverse requirements of various applications, transparent polyamide elastomer was successfully synthesized by one-step polycondensation of isophthalic acid (IPA) adipic acid (ADA), 4,4'-diaminodcoiicyclohexylmethane (PACM), hexamethylenediamine (HMD) and polyether amine (ED900). The polyamide hard segments confer excellent strength , toughness, wear resistance, chemical stability, low-temperature impact resistance and self-lubrication to the material. Simultaneously, the polyether soft segments enhance the material's ductility and flexibility. The elastomers exhibited outstanding thermal stability, transparency of ∼91% and mechanical properties with tensile strength of 26–29 MPa and elongation at break of 300% - 600%. Among them, two elastomers with broad glass transition temperature possessed multiple shape memory behavior, and showed no crease after cyclic folding up to 10,000 times demonstrating excellent bending fatigue resistance to long-time and repeated deformation. Therefore, the novel transparent polyamide elastomer with the advantages of good transparency, flexibility, wear and fatigue resistance can be sprayed or daubed in solution on the surface as a smart and peelable protective coating, holding vast potential for widespread applications in the fields of electronic devices, flexible display and optical devices. • Transparent polyamide elastomer is prepared by one-step copolymerization. • The elastomer has high transparency, wear resistance and fatigue resistance. • The elastomer solution can be sprayed or daubed on the surface as smart coating.