Single-phase block copolymers by cross-metathesis of 1,4-cis-polybutadiene and 1,4-cis-polyisoprene

摘要

AbstractMacromolecular Cross-Metathesis (MCM) reactions on commercial Polybutadiene (PBD) and Polyisoprene (PIP) homopolymers, in the presence of first generation Grubbs and Hoveyda-Grubbs catalysts, are reported.13C-NMR resonances of butadiene(B)/isoprene(I) heterosequences show block-copolymer formation, with blocks longer than a hundred monomer units, even for long reaction times. DSC scans of MCM products show that, with MCM time, PBD crystallinity progressively disappears while the well separated Tgof the two homopolymers merge to an intermediate single Tg. This indicates that PBD and PIP blocks are completely miscible when their lengths are reduced to a few hundred units.13C NMR spectra also show that, for the considered MCM process, double bond isomerizations are definitely more frequent than heterosequence formations.Graphical abstractDisplay OmittedHighlights<