Chiral Catalyst Leads To New Stereopolymer

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Taking advantage of a chiral cobalt catalyst, chemists this year copolymerized propylene oxide enantiomers and succinic anhydride to form poly(propylene succinate), the first member of a new class of thermoplastics (J. Am. Chem. Soc. 2014, DOI: 10.1021/ja509440g). Geoffrey W. Coates and coworkers at Cornell University developed the new polymer. It forms a semicrystalline stereocomplex, meaning it’s a material made from combining right- and left-handed polymer chains. Combining the two polymer chains allows them to crystallize together in ways they can’t do alone, giving polymer chemists better control over the thermal properties and biodegradability of polymers. Stereocomplexes are exceedingly rare, however, with only about a dozen examples known. Coates and graduate students Julie M. Longo and Angela M. DiCiccio first designed a chiral cobalt catalyst, and then using either the (R,R) or (S,S) version of the catalyst, they copolymerized (R)- or (S)-propylene oxide with succinic anhydride to produce (R)- or (S)-poly(propylene ...