Hierarchical supramolecular self-assembly of Bi-Valine-Containing Poly(phenylacetylene) and tunable chirality

Abstract

A challenging aim is the precisely controlled construction of hierarchical chiral self-assembly in synthetic polymers both from the fundamental and advanced technological development perspectives. Amphiphilic polymers can be assembled into well-organized aggregates with morphological varieties, and external stimuli remarkably affect their self-assembly behavior. We designed and synthesized an amphiphilic helical poly(phenylacetylene) homopolymer containing bi-valine pendants. The hierarchical chiral self-assembly behavior of the homopolymer was realized and investigated by adding a polar solvent into the poly (L-1) solution. Furthermore, the influences of the solvent components and temperature on the supramolecular chirality and morphologies of the ordered nanostructures were studied via circular dichroism (CD), transmission electron microscopy (TEM), and dynamic light scattering (DLS). Various morphologies such as spheres, beads-string micelles, vesicles, nanorods, flower-like, and blocky nanostructures were obtained. The polyphenylacetylene backbone was successfully endowed with chirality from L-Boc-valine pendants, and this property was further transferred and enhanced in high-ordered supramolecular self-assemblies. With the increase of polar solvent fraction, the enhanced driving force of solvophobic interaction and π-π stacking might significantly promote the aggregation of multi micelles.