Length-Dependent Melt Self-Assembly of A/B Core-Shell Molecular Bottlebrushes: Molecular Shape Influences Morphology

Microphase separated A/B block copolymers self-assemble into a plethora of one-, two-, and three-dimensional spatially periodic nanostructures, as a consequence of simultaneous minimization of energetically unfavorable A-B monomer contacts and entropically unfavorable chain stretching. While the composition-dependent phase behaviors of linear A/B block copolymers are well-known, the morphological and thermodynamic implications of end-linking narrow dispersity linear AB diblocks into nonlinear core-shell bottlebrush polymers (csBBs) are less well-studied. This talk will describe investigations of the melt phase behaviors of csBBs, focusing on how changes in the backbone length at fixed side chain compositions influence the stabilities and structures of their self-assembled lamellar, cylindrical, and spherical morphologies. These studies reveal the minimum backbone length for a "star-to-bottlebrush transition" and how nonlinear chain architecture and non-Gaussian graft side chain stretching change their preferred morphologies relative to linear homologues.