Achiral Additives Modulated Helicity and Supramolecular Fibrillation Assembly of Helical Dendronized Poly(phenylacetylene)s through Enhanced Radial Amphiphilicity ^†

Comprehensive Summary Non‐covalent interactions with additives have been demonstrated to be intriguing in conferring racemic polymers with preferential one‐handed helical conformation. However, these additives are normally chiral, and specific interactions are demanded. We report herein the modulation of helicity from thermoresponsive helical dendronized poly(phenylacetylene)s (PPAs) in aqueous media by using achiral aromatic additives at different temperatures. These dendronized PPAs carry dendritic oligo(ethylene glycol)s (OEGs), which exhibit characteristic thermoresponsive behavior with their cloud points ( T cp s) governed by the peripherals of the dendritic OEGs. Notably, these polymers can undergo helical conformation inversion across their thermal phase transitions. However, such inversion can be modulated by the presence of achiral aromatic additives, including benzoic acid, phenol, and aniline. These aromatic achiral compounds increase hydrophobicity of the polymers to decrease their T cp s, and act as molecular glues to greatly enhance intermolecular aggregation of the helical PPAs at elevated temperatures. In contrast to the thermally aggregated micelles typically observed from thermoresponsive polymers above their T cp s, the presence of aromatic additives intriguingly promotes the formation of long helical fibers alongside double helices from aqueous polymer solutions above the T cp s. Molecular dynamics simulations are employed to elucidate the competitive interactions among the dendronized PPA chains, the additives, and water.