Reprocessable and self-healable boronic-ester based poly(styrene-b-isoprene-b-styrene) vitrimeric elastomer with improved thermo-mechanical property and adhesive performance

It is fascinating to develop vitrimeric elastomers with excellent processability and improved physical properties through incorporating reversible covalent bonds into traditional thermoplastic elastomers. In this work, a poly(styrene-b-isoprene-b-styrene) (SIS) thermoplastic elastomer was selected as the base elastomer and converted into vitrimer through peroxide-induced crosslinking reaction with di-vinyl-terminated boronic ester crosslinker. Kissinger model predicts that the activation energy of vitrimer crosslinking process is slightly higher than that of chemical crosslinking process. The peroxide content was adjusted to tune the composition of permanent chemical crosslinks and dynamic chemical crosslinks. In this way, SIS vitrimer elastomer with tailored multiple network structure was successfully prepared. The stress relaxation behavior of all SIS-BE samples shows Arrhenius-type temperature-dependency and the bond-exchange activation energy (Ea) of SIS-D0.5-B5 sample was estimated as 44.14 kJ/mol. SIS vitrimer elastomer shows improved creep-resistance, comparative mechanical strength and elastic recovery in relative to crosslinked SIS elastomer while maintaining good reprocessbility and self-healing efficiency. Additionally, SIS vitrimeric elastomer shows an increased lap-shear strength from 0.53 MPa to 1.02 MPa with the increase of DCP content. Therefore, we have demonstrated the potential for industrial-scale production of SIS vitrimer elastomer and its applications as reprocessable and healable adhesives.