Extremely tough block polymer-based thermoplastic elastomers with strongly associated but dynamically responsive noncovalent cross-links

Abstract

To develop elastomers with excellent mechanical properties and processability, block copolymer-based thermoplastic elastomers (TPEs) with dynamic noncovalent cross-links have been actively studied in recent years. Most previous studies on such block copolymer-based TPEs have focused on incorporation of hydrogen-bonded cross-links into the block with a glass transition temperature lower than room temperature; however, the difference between the mechanical properties of hydrogen-bonded TPEs and those of other noncovalent-bonded TPEs has been hardly discussed. This work uses the polystyrene-b-polyisoprene-b-polystyrene (SIS) triblock copolymer produced in industry to synthesize hydrogen-bonded (hSIS) and ionically functionalized thermoplastic elastomers (iSIS) and compares their mechanical properties. iSIS is much tougher than hSIS; remarkably, iSIS exhibits an excellent toughness of 480 MJ m−3, because the ionic multiplets in iSIS serve as much more strongly associated but reversible cross-links. Since the elastomers can be produced at industry scale, they have great market potential for becoming next-generation elastomeric materials.