Phase Segregation in Thin Films of Conjugated Polyrotaxane– Poly(ethylene oxide) Blends: A Scanning Force Microscopy Study

Abstract

Scanning force microscopy (SFM) is used to study the surface morphology of spin‐coated thin films of the ion‐transport polymer poly(ethylene oxide) (PEO) blended with either cyclodextrin (CD)‐threaded conjugated polyrotaxanes based on poly(4,4′‐diphenylene‐vinylene) (PDV), β‐CD–PDV, or their uninsulated PDV analogues. Both the polyrotaxanes and their blends with PEO are of interest as active materials in light‐emitting devices. The SFM analysis of the blended films supported on mica and on indium tin oxide (ITO) reveals in both cases a morphology that reflects the substrate topography on the (sub‐)micrometer scale and is characterized by an absence of the surface structure that is usually associated with phase segregation. This observation confirms a good miscibility of the two hydrophilic components, when deposited by using spin‐coating, as suggested by the luminescence data on devices and thin films. Clear evidence of phase segregation is instead found when blending PEO with a new organic‐soluble conjugated polymer such as a silylated poly(fluorene)‐alt‐poly(para‐phenylene) based polyrotaxane (THS–β‐CD–PF–PPP). The results obtained are relevant to the understanding of the factors influencing the interfacial and the intermolecular interactions with a view to optimizing the performance of light‐emitting diodes, and light‐emitting electrochemical cells based on supramolecularly engineered organic polymers.

Self‐Assembled Conjugated Thiophene‐Based Rotaxane Architectures: Structural, Computational, and Spectroscopic Insights into Molecular Aggregation

“…The self‐assembly of water‐soluble conjugated polyrotaxanes has been recently investigated by some of us with atomic force microscopy (AFM). This made it possible to visualize isolated CD‐threaded conjugated polymers both neat1b and complexed with poly(ethylene oxide) at the single‐molecule level1c and in phase‐segregated 100 nm‐thick blend films 9. Isolated polydisperse rotaxane structures consisting of CDs threaded on poly(ethylene glycol) were also studied on a molecular scale by scanning tunneling microscopy (STM): hydrogen‐bonding interactions among CDs were found to rule the position of the CDs in a molecular necklace 10…”

Highly-organized stacked multilayers via layer-by-layer assembly of lipid-like surfactants and polyelectrolytes. Stratified supramolecular structures for (bio)electrochemical nanoarchitectonics

“…It is also observed that the film morphology is not strongly influenced by the chemical nature of the capping layer, as confirmed in the recorded AFM height images. The contrast in the AFM phase images (see supporting information file for details, Fig.1S) does not provide evidence for the presence of patches, islands or phase-segregated domains, 57 pointing to a favorable interaction between PAH and DP units that leads to the uniform spreading of each layer during the assembly step.…”

Enhanced electroluminescence of organic light-emitting diodes by using halloysite nanotubes

“…Such flake mesostructures, formed by absorbed small grains, have been attributed to highly entangled polymer chains [16,17]. Entangled chains have a higher propensity for interchain contact causing exciton-exciton annihilation.…”