Phospharubber makes its debut

Natural rubber (polyisoprene) and a variety of synthetic analogs such as poly(styrene-butadiene) have been commercially important polymeric materials for going on 200 years. Derek P. Gates and coworkers at the University of British Columbia have now introduced the first phosphorus-containing variants: poly(1-phosphaisoprene) and poly(phospha-1,3-butadiene). Gates’s group has previously focused on using phosphaalkenes as monomers for creating phosphorus-containing polymers for flame retardant, catalyst, and sensor applications. These materials contain functional phosphine units in the polymer backbone. Seeking to expand on the work, Gates and his team prepared phosphadiene monomers that would lead to polymers containing P=C or C=C repeat units, enabling additional functionalization opportunities such as copolymerization and cross-linking (Angew. Chem. Int. Ed. 2017, DOI: 10.1002/anie.201703590). Polymerization of the phosphadienes occurs mostly through their C=C bonds, with the majority of the phosphorus atoms forming side chains that maintain the P=C double bonds. The P=C/C=C hybrid monomers thus open the door to incorporate phosphorus into commercial butyl rubber or styrene-butadiene rubber that traditionally uses isoprene or butadiene comonomers, Gates says, offering unique properties compared with the carbon-only analogs. In one potential application, the researchers found they can bind gold ions to phosphorus in poly(1-phosphaisoprene), making it a promising catalyst support material.