Nanoscale Fibrils and Grids: Aggregated Structures from Rigid-Rod Conjugated Polymers

Abstract

Langmuir−Blodgett (LB) molecular processing of conjugated polymers [poly(phenylene ethynylenes)] into highly aligned films has revealed conditions for the formation of liquid crystalline monolayer films that structurally evolve into fibril aggregates. The structural requirements for poly(phenylene ethynylene)s to display liquid crystalline phases capable or alignment by LB methods were determined. The reconstruction of monolayers into fibril structures was found to require a low glass-transition temperature (Tg), weak surface anchoring, and a monolayer with a high energy that can be stabilized by reorganization. This assembly of polymers into aggregated structures produces rigid structural units analogous to naturally occurring fibrous proteins such as collagen and elastin. These oriented, shape-persistent nanoscale structures create new possibilities for the construction of complex supramolecular structures, and this capability has been demonstrated by the formation of a nanoscale grid.