Synthesis and Ring-Opening Metathesis Polymerization of Norbornene-Terminated Syndiotactic Polypropylene

Using nonliving bis(phenoxyimine)titanium catalysts activated by methylaluminoxane (MAO) in the presence of propylene, allyl-terminated syndiotactic polypropylene macromonomers with varying tacticity ([rrrr] = 0.80 and 0.94) and molecular weight (Mn = 3600 and 5600 g/mol) were produced. The end-functionalized polymers were converted to hydroxyl- and subsequently norbornene-terminated macromonomers. Two series of syndiotactic polypropylene comb-polymers were synthesized through metathesis polymerization of the norbornene-functionalized polypropylene. The molecular weight (Mn = 46 000–172 000 g/mol) and polydispersity (Mw/Mn = 1.21–1.89) of the comb polymers was determined by gel permeation chromatography (GPC). Using differential scanning calorimetry (DSC), melting temperature (Tm) and crystallization temperature (Tc) were determined and both were observed to decrease with increasing conversion to poly(macromonomer). To the best of our knowledge, this is the first synthesis of comb-polymers from end-functionalized syndiotactic polypropylene.