Discrete Diblock Copolymers with Precise Stereoconfiguration

Abstract

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 σ 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.

Tuning the Complex Spherical Phase of Sugar-Based Block Co-Oligomer via Single-Monomer-Mediated Composition Variation

“…These BCOs not only constitute a single-component system but also possess monodisperse molecular weights. The recent studies by Dong et al on a series of monodisperse discrete BCPs with precisely controlled sequence, architecture, and stereoconfiguration have also unveiled the emergence of FK phases and DDQC in these materials. − These findings, combined with the results presented here, affirm that molecular weight polydispersity is not a prerequisite for accessing FK phases, although such inhomogeneity may enhance their stability. Figure displays the morphological diagrams of the BCOs determined from the SAXS results collected in the heating and cooling cycle.…”