Covalent modification of poly(vinyl chloride) via organometallic Barbier reaction

Abstract

The development of efficient synthetic methodologies for chemical functionalization and modification of existing polymers to improve or diversify the physicochemical and mechanical properties is an ongoing quest in macromolecular science. This is especially true for the generation of polymeric materials out of commercial/commodity polymers via structural tailoring since these polymers are produced in vast quantities and are structurally diverse. In this study, we report on benign chemical modification of an important commercial polymer, poly(vinyl chloride) (PVC) via Barbier reaction. The methodology is based on the employment of magnesium metal to generate nucleophilic alkyl-magnesium chloride groups on polymer backbone and addition of these nucleophilic centers to electrophilic carbonyl groups. The synthetic procedure can be implemented in a one-pot fashion by utilizing commonly available aldehyde or epoxide bearing compounds along with elemental magnesium. The Barbier addition of PVC backbone generated alkyl-magnesium chloride groups on the model aldehyde substrates with different structures were achieved with > 84 % functionalization degrees. It was shown that the functionalization degrees can easily be regulated by the simple alteration of employed magnesium ratio to backbone present alkyl chloride groups. Functionalization studies were investigated via 1H NMR, FT-IR and SEC analyses as well as contact angle measurements. Considering the wide industrial/ research utilization of poly(vinyl chloride) together with commercial availability, abundant reactive alkyl chloride bonds in backbone chains of this polymer offer easy to implement structural tailoring via proposed organometallic Barbier reaction.