Self-Organization of Hairy-Rod Polymers

Abstract

Self-organized structure formation in the melt of hairy-rod polymers is analyzed theoretically. It is shown that the interplay between unfavorable repulsive rod-coil interactions and stretching of the side chains is responsible for the appearance of three different microphases: one lamellar and two hexagonal. The first-order phase transitions between these are considered in detail. If the side chains are long enough for the elastic stretching free energy to dominate the repulsive interactions, hexagonally ordered domains of hairy-rod cylindrical brushes are formed. The lamellar phase is shown to be stable for shorter side chains and occupies an important part of the phase diagram. In the intermediate side chain length regime another hexagonally ordered structure appears, characterized by cylindrical micelles with an elongated cross section, containing several hairy-rod polymers.

Transport and Electro‐Optical Properties in Polymeric Self‐Assembled Systems

“…The covalently bonded sidechains can also be regarded as "bound solvent molecules" and they also render surface activity towards another solvent phase. But additionally, the side-chains can lead to self-assembly as the flexible side-chains are repulsive [262,273]. For example, poly(p-phenylene) (PPP) is an insoluble and infusible conjugated polymer.…”

“…The polymers self-assemble to cylindrical or lamellar phases depending on the type and length of the alkyl chains [264,266]. The nature and length of the covalently bonded side-chains have a large effect on the phase behavior [273]. Alkyl-substituted polythiophenes ( Fig.…”

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

“…Here, the parameters d and b describe the size of the backbone, see Scheme 1. In the covalent hairy rods, minimization of the free energy as a function of the volume fraction of rods f for various microphase-separated morphologies predicts 15 the lamellar (Lam) and two types of cylindrical morphologies, denoted by Hex1 and Hex2, as depicted in Scheme 1. Spherical structures do not occur.…”

Effect of side-chain asymmetry on the intermolecular structure and order-disorder transition in alkyl-substituted polyfluorenes

“…Hairy-rod polymers consist of a stiff backbone and flexible side chains that organize into alternating backbone and side-chain layers and experience an order-disorder transition (ODT) on heating [1][2][3][4][5]. Phase behavior of alkyl-substituted conjugated polymers can be understood in similar terms, and this was illustrated early with polythiophenes [6,7].…”