Self-assembled, aligned, and cleaved supramolecules of poly(2,5-pyridinediyl)

Abstract

We report on directed self-assembly in supramolecules containing rod-like polymers. The comb-shaped supramolecules consist of poly(2,5-pyridinediyl), camphorsulfonic acid, and hydrogen bonded amphiphilic side chains. Locally they form highly ordered lamellar structures in which the polymers are stacked. The liquid crystalline state allows facile overall alignment yielding absorption dichroism and polarized photoluminescence. After alignment, cleavage of the amphiphiles results in solid films which retain this optical anisotropy with the high photoluminescence quantum yield. CONCLUSIONSConjugated rod-like polymer, PPY, forms comb shaped supramolecules which assemble in highly ordered smectic local structures and can be aligned to form directed assembly. High absorption dichroism and polarized PL are observed. Hydrogen bonded amphiphiles can be cleaved after alignment, which retains optical anisotropy and improve PLQY.

Structure and Phase Equilibria of Polyelectrolytic Hairy-Rod Supramolecules in the Melt State

“…The observed behavior is even more appreciable than in thiophenes (e.g., polyoctylthiophenes), which are considered prime examples of such directed self-assembly by π-stacking . This particularly manifests itself in the organization at surfaces and interfaces. ,,, Here, the effect is likely enhanced by the aromatic headgroup in the amphihile. Thus, the current system might be likened to “ hairy boards ” 35 rather than rods.…”

“…Hairy-rod polymers consist of a rigid or semirigid backbone where a dense set of side chains is bonded in a comb-shaped manner. − The concept allows self-organization and improved solubility even for polymers of rigid rodlike backbone. Unlike hairy-rod polymers with rodlike polymer backbone and covalently bonded flexible side chains, supramolecular hairy-rod polymers have the side groups connected to the backbone by physical bonds, − see Scheme . Theoretical treatments of the self-organized structure formation of hairy-rod polymers and supramolecular hairy-rod polymers have recently been presented.…”

“…In contrast to the covalently bonded ones, the coils and rods of the supramolecular hairy rods characteristically tend to macroscopically phase separate, because of small mixing entropy and aggregation tendency of the rods, thus requiring a particularly strong attractive interaction between the rods and coils. The side chains can also be removed after alignment, thus yielding aligned pristine material. , The direct comparison of the melt-state phase behavior of supramolecular hairy rods between the experiment and theory seems to be scarce. We have carried out experiments to investigate the structure and phase behavior of supramolecular hairy rods.…”

“…Understanding the phase behavior of hairy rods 15 is important to design liquid crystallinity 17,18 which allows facile alignment of the otherwise crystalline infusible and intractable polymers. With conjugated polymers, 19,20 the alignment results in anisotropy of their optical 12,13 and electronic 21 properties. The alignment of conjugated hairy rods in thin films can also result in completely new structural features 22 compared to the bulk.…”

“…The side chains can also be removed after alignment, thus yielding aligned pristine material. 12,13 The direct comparison of the melt-state phase behavior of supramolecular hairy rods between the experiment and theory seems to be scarce. We have carried out experiments to investigate the structure and phase behavior of supramolecular hairy rods.…”