Polybutadiene rubbers with urethane linkages prepared by a dynamic covalent approach for tire applications

Abstract

In the context of pneumatic tires, high durability and fuel efficiency reside in a trade-off relationship. This problem may be solved by the introduction of hydrogen bonds into cured rubber, as elastic materials with hydrogen bonds exhibit a different strain dependence of their energy dissipation compared to elastic materials with conventional chemical bonds. Herein, we have applied cross-metathesis reactions between polybutadienes and olefin-containing polyurethanes to the synthesis of novel polybutadienes with urethane linkages as a source of hydrogen bonds in the polymer main chain (PBUs). A series of PBUs with different contents of urethane linkages was synthesized by changing the feed ratios of the polybutadiene and olefin-containing polyurethanes in cross-metathesis reactions, and the resulting PBUs were characterized in order to examine the effect of the hydrogen bonds on the macroscopic mechanical properties. Cured rubber materials prepared from PBUs exhibit higher tearing energy and energy dissipation at high strains compared to conventional control rubber samples, and the tearing energy related to energy dissipation at high strains improves with increasing urethane content. Therefore, the present approach represents a powerful strategy for conciliating durability and fuel efficiency in cured rubbers.