Discrete Diblock Copolymers with Precise Stereoconfiguration

This work develops an iterative growth approach to synthesize discrete oligo lactic acids with exactly defined stereoconfiguration by connecting enantiomeric monomers (i.e., L-and D-lactic acid) following a predesigned sequence. A library of diblock copolymers with uniform chain length was modularly prepared by conjugating the stereoisomeric blocks with a chemically incompatible chain. The precise chemical structure eliminates all molecular uncertainties associated with statistical distribution and decouples the intertwined variables. A rich collection of ordered structures, including unconventional Frank-Kasper A15 and sigma phases, was captured. The stereoconfiguration exerts pronounced impacts on chain conformation, leading to appreciable variations of lattice dimension and phase stability. This study quantitatively assessed the critical contribution of stereoconfiguration on packing behaviors, calling for particular attention to this essential molecular parameter as an effective handle for rational structural engineering.