Aggregation of a polyphilic Janus polythiophene in solution

Solutions of poly(4'-perfluorooctyl-3-octyl-2,2'-bithiophene) display strong thermochromism and solvatochromism that are consistent with formation of solid-state-like aggregates. The polyphilicity of the structure (having alkyl, fluoroalkyl, and arene segments) provides a Janus structure in which the two edges of a ribbonlike polymer chain have distinctly different surface energies. In addition, the placement of electron-donating and electron-withdrawing substituents provides an alternation of charge density along the polymer backbone. The chromic effects are not observed for analogous polymers that only have one type of side chain or for an analogue with alternating alkyl and semifluoroalkyl side chains that is polyphilic but does not have the alternation of charge density along the polymer chain.