Derivatization of propene/methyloctadiene copolymers: A flexible approach to side-chain-functionalized polypropenes

The copolymerization of propene with 7-methyl-1,6-octadiene (MOD) catalyzed by Cp*TiMe₃/B(C₆F₅)₃ (A) and rac-C₂H₄(Ind)₂ZrCl₂/methylaluminoxan e (B) in toluene under 1 bar propene gave copolymers with unsaturated side chains. Under these conditions, catalyst A produced copolymers with an atactic backbone structure of type 1, with 3.5-19.6 mol % MOD incorporation and weight-average molecular weight = 0.7-2.7 × 10⁵. Using catalyst B, copolymers 2 with 0.4-3.8 mol% MOD incorporation were prepared. The comonomer incorporation was a linear function of the feed ratio. The titanium catalyst A had a significantly higher affinity for MOD than the sterically more hindered zirconocene B. Postpolymerization modification of the side-chain C=C bond allowed the facile introduction of a wide variety of functional groups. Epoxidation and especially ozonolysis of the C=C bond, to give -CHO and -COOH functionalized copolymers, proved to be very facile routes to functionalized polypropenes. According to monitoring by NMR, most of these transformations proceed in an essentially quantitative conversion. As an example of potential applications of such polymers, polypropenes with covalently attached dyes were prepared that are suitable for blending.