Isospecific polymerization of (E)-4,8-dimethyl-1,3,7-nonatriene (DMNT) and its binary copolymerization with ethylene and styrene using Ti[OSSO]/MAO catalysts

The inertness of saturated C–C bonds renders polyolefins exceptionally stable, yet making chemical modification prohibitively difficult. The presence of double bonds in the backbone grants these polymers diverse reactivities and, therefore, offers universal platforms for building an array of new-generation functional polyolefins. This study explores the polymerization of the bio-based monomer (E)-4,8-dimethyl-1,3,7-nonatriene (DMNT) using titanium complexes with [OSSO]-type ligands, showing notable regio- and stereoselectivity. The catalyst 2, bearing cumyl substituents, exhibits exceptional performance, producing highly isotactic poly(DMNT) with a predominance of 1,2-insertion. Furthermore, the binary copolymerization of DMNT with ethylene and styrene was exploited to produce corresponding copolymers with varying levels of unsaturation. Successful incorporation of the comonomer was also evidenced by NMR characteristic signals. Even in these cases, DMNT was preferentially inserted in the 1,2-insertion at a remarkably high ratio (up to 98.0 mol%). At a constant DMNT concentration, increasing the ethylene pressure from 0.2 bar to 1.0 bar promoted DMNT conversion from 28.8 mol% to 85.8 mol%, accompanied by a two-fold increase in polymer yield. This result underscores the crucial role of ethylene-terminated chains in enhancing cross-propagation efficiency. DMNT incorporation and molecular weights were more precisely controlled for styrene copolymers. This control nature allowed for the unprecedented synthesis of styrene-DMNT block-like copolymers via carefully sequential monomer addition. Subsequent modification of the internal olefin group led to the formation of corresponding epoxidized copolymers. A variety of characterization techniques confirmed the desired chemical structures, improved surface wettability, and latent reactivity of the resultant epoxy-functionalized copolymers.