Metathetic Degradation of Styrene-Butadiene Rubber via Ru-Alkylidene Complex Catalyzed Reaction

Metathetic degradation and functionalization of styrene-butadiene rubber (SBR) were performed with allyl hexanoate, allyl chloroacetate, 5-hexenyl acetate and trifluoroethyl methacrylate as chain transfer agents (CTAs) using Grubbs 2SUPnd/SUP generation catalyst. It has been demonstrated that the catalyst concentration, CTA concentration and reaction time were major factors influencing the molecular weights and polydispersity indices of targeted telechelic SBR oligomers. Well-defined oligomers with molecular weights ranging from 700 to 36600 g molSUP-1/SUP and polydispersity indices ranging from 1.17 to 4.79 were realized. The structures of the SBR oligomers were determined by FTIR and SUP1/SUPH NMR analyses, which indicated that the functional groups of the CTAs were successfully attached onto the end of the polymer chains. To further investigate the performance of SBR oligomers, differential scanning calorimetry (DSC) analysis was performed, which indicated that the glass transition temperature (TSUBg/SUB) of the metathesis products decreased with longer reaction time.