Self-Assembly of a Conjugated Polymer: From Molecular Rods to a Nanoribbon Architecture with Molecular Dimensions

Abstract

Abstract:The growth from solution of novel end-functionalised poly(para-phenyleneethynylene)s (PPEs) on flat solid crystalline substrates was investigated. The macromolecular structure of PPE at the interface between the basal plane of graphite and an organic solution was visualised with molecular resolution by scanning tunnelling microscopy. It revealed a two-dimensional nematic-like molecular order of the polydisperse polymer, while a corresponding shorter and monodisperse oligomer exhibited an epitaxial 2 D crystal structure. In contrast, on the insulating substrate mica, PPE can self-assemble into micrometer-long nanoribbons. Their crosssection was determined quantitatively by scanning force microscopy in tapping mode; this revealed a typical thickness of two molecular layers and a width distribution that is well described by the distribution of molecular weights, according to the Schulz ± Zimm distribution. This indicates that the polymers are fully extended in the ribbons and oriented with the conjugated backbone parallel to the substrate and perpendicular to the long axis of the ribbons. Unlike previous studies carried out interfacing single molecules to metallic probes, we propose here functionalised ribbons as polymolecular architectures, which could be used to interconnect gold nanoelectrodes in a molecular-scale electronic device.

Optical properties of amphiphilic copolymer-based self-assemblies

“…After copolymerizing the polymers with hydrophilic coil blocks, in addition to conventional spherical micelles and vesicles, unique self-assembled structures such as helices [53,54], ribbons [55], rings [56], and tubules [57,58] are frequently observed owing to ordered alignment of rigid rods [9]. In the aggregates, the packing style of conjugated rods can remarkably affect the final optical properties.…”

Fluctuation Effects in Semiflexible Diblock Copolymers

“…For several decades, numerous experimental and theoretical works have established our foundational understanding of polymeric self-assembly. ,− In the theoretical study of the phase behavior of copolymers, polymer field theory has been the primary theoretical framework, and the majority of the work implementing polymer field theory uses the Gaussian chain model and mean-field theory. The Gaussian chain model assumes polymer configurations exhibit random walk statistics .…”

Generation of Low-Dimensional Architectures through the Self-Assembly of Pyromellitic Diimide Derivatives

“… 10 − 18 Such systems have been investigated for their unique optical properties as dyes 19 − 22 and for their tendency to self-assemble into macroscopic supramolecular electroactive aggregates. 23 By modifying the experimental conditions and functionalization of the aromatic core, one can produce various types of aggregates such as nanowires, 24 nanoribbons, 25 and nanotubes. 26 , 27 These structures can be extremely useful and can be of interest for different technological applications in the field of organic photonics and electronics, 28 , 29 photovoltaics, 30 , 31 and sensing.…”