Crystalline Stereocomplexed Polycarbonates: Hydrogen‐Bond‐Driven Interlocked Orderly Assembly of the Opposite Enantiomers

Abstract Four novel crystalline stereocomplexed polymers are formed by mixing isotactic ( R )‐ and ( S )‐polycarbonates in 1:1 mass ratio. They show the enhanced thermal stability and new crystalline behavior, significantly distinct from the component enantiomer. Two stereocomplexed CO 2 ‐based polycarbonates from meso ‐3,4‐epoxytetrahydrofuran and 4,4‐dimethyl‐3,5,8‐trioxabicyclo[5.1.0]octane have high melting temperatures of up to 300 °C, about 30 °C higher than the individual enantiomers. Isotactic ( R )‐ or ( S )‐poly(cyclopentene carbonate) and poly( cis ‐2,3‐butene carbonate) are typical amorphous polymeric materials, however, upon mixing both enantiomers together, a strong interlocked interaction between polymer chains of opposite configuration occurs, affording the crystalline stereocomplexes with melting temperatures of about 200 °C and 180 °C, respectively. A DFT study suggests that the driving force forming the stereocomplex is the hydrogen‐bonding between carbonate units of the opposite enantiomers.