Fabrication of long chain branched polypropylene using click chemistry

This article presents a new method to produce LCBPP with well-defined structures via Huisgen's 1,3-dipolar cycloaddition of azide and alkyne (click reaction). Azide-terminated isotactic polypropylene (iPP) (iPP-St-N-3) was synthesized via the hydrochlorination and subsequent substitution of the starting styryl-terminated i-PP (i-PP-t-St), which is the product of a metallocene-mediated isospecific propylene polymerization governed by a controlled chain transfer reaction. Alkyne-grafted iPP (iPP-g-a parts per thousand) can be produced with high efficiency through one-pot esterification and the subsequent amidation of hydroxyl-functionalized iPP. Detailed analysis of the product by H-1 NMR, FTIR, DSC, and GPC reveals a clean and clear formation of LCBPP.