Synthesis, Photophysics, and Langmuir Films of Polyfluorene/Permodified Cyclodextrin Polyrotaxanes

Abstract

In the present study, we investigated the effect of permodified 2,3,6-tri-O-trimethylsilyl β- and γ-cyclodextrin (TMS·β-CD, TMS·γ-CD) encapsulation on the optical, electrochemical, morphological, and supramolecular arrangements of a poly­[2,7′-(9,9-dioctylfluorene-alt-2′,7-fluorene)] PF copolymer. For this purpose, the photophysical properties and Langmuir monolayer formation of PF·TMS·β-CD and PF·TMS·γ-CD polyrotaxanes were investigated and compared with those of the reference PF. Surface pressure–area isotherms and Brewster angle microscopy studies indicated the capability of both polyrotaxanes to organize into larger and homogeneous 2D supramolecular assemblies at the air–water interface. The obtained results suggest that the presence of the surrounding TMS·β-CD and TMS·γ-CD macrocycles on the PF backbones leads to changes in the conformation and hydrophobicity of the film surfaces. Our investigation offers a method to assess the impact of TMS-CD encapsulation on the control of 2D monolayer formation, with particular attention on the generation of stable PF monolayers for organic electronic devices.

Novel Insight into the Photophysical Properties and 2D Supramolecular Organization of Poly(3,4-ethylenedioxythiophene)/Permodified Cyclodextrins Polyrotaxanes at the Air–Water Interface

“…The fluorescence lifetime (τ) of PEDOT∙TMe-βCD and PEDOT∙TMe-γCD ( Table 3 ) in both H 2 O and ACN exhibited bi-exponential decay traces, which were assigned to the contribution of intrachain emission and excitonic contribution [ 38 ]. We also note that the PEDOT∙TMe-βCD and PEDOT∙TMe-γCD exhibited both Φ PH and Φ FL in ACN, whereas in H 2 O these efficiencies are too low, evidencing mainly nonradiative pathways [ 16 , 39 ].…”

“…To generate polyrotaxane (PR) architectures, bulky stoppers covalently attached at both ends of the CPs’ backbones are required. As a result of significant interest in manipulating the distance between CPs backbones and preventing crosstalk, a relatively large number of PP and PR architectures containing different host molecules have been reported [ 16 , 17 , 18 , 19 , 20 , 21 , 22 ]. These supramolecular materials exhibit a crucial importance for further development of organic electronics and represent a key bottom-up strategy to build and process relatively soft functional materials.…”

“…It has been shown that this approach can be used for a diminished tendency toward aggregation and to obtain a wide variety of supramolecular architectures by combination of different conjugated guest and macrocyclic host molecules [ 15 , 23 , 24 ]. Alongside other macrocyclic hosts, several types of permodified cyclodextrins (CDs) derivatives were used for the synthesis of PP and PR architectures [ 16 , 17 , 21 , 22 ]. Due to their hydrophobic cavities and surfaces, these host molecules have the ability to thread appropriately sized monomers and oligomers/polymers by cooperation of various noncovalent interactions, such as hydrophobic, electrostatic, or van der Waals.…”