Targeted β-Phase Formation in Poly(fluorene)–Ureasil Grafted Organic–Inorganic Hybrids

Abstract

The development of synthetic strategies to control the molecular organization (and inherently linked optoelectronic properties) of poly(fluorene)s is critical for the development of efficient light-emitting devices. Here, we report a facile route using sol-gel chemistry to promote the formation of the β-phase through the covalent-grafting of poly[(9,9dioctylfluorene)-co-(9,9-bis(8-hydroxyoctyl)fluorene)] (PFO-OH) to poly(oxyalkylene)/siloxane hybrids known as ureasils, due to the urea linkages binding the organic and inorganic components. Although grafting occurs within the siliceous domains, the degree of branching of the organic backbone determines the packing of the PFO-OH chains within the ureasil framework. Moreover, photoluminescence studies indicate that physical 2 confinement also plays a key role in promoting the evolution of the β-phase of PFO-OH as the sol-gel transition proceeds. Spectroscopic and structural analyses reveal that di-branched ureasils promote linear packing of the PFO-OH chains, whilst tri-branched ureasils exhibit a more open, distorted structure, that restricts the packing efficacy and reduces the number of covalent anchorages. These results indicate that the organic-inorganic hybrid structure induces distinct levels of β-phase formation and that covalent-grafting is a versatile approach to design novel poly(fluorene) hybrid materials with tailored optical properties. T-403, d-UPTES, t-UPTES, DU-PF-x and TU-PF-x, PXRD, 13 C and 29 Si MAS-NMR, supporting PL measurements (emission and excitation spectra, Gaussian deconvolution, PL quantum yields). The following files are available free of charge. Meazzinietal_2017_ESI.pdf AUTHOR INFORMATION

Luminescent Solar Concentrators Based on Energy Transfer from an Aggregation-Induced Emitter Conjugated Polymer

“…The dU(600) structure consists of siliceous nanodomains (∼10 Å) covalently bonded to the Jeffamine chains via propylurea linkages. 50 To optimize the concentration of the donor p-O-TPE, as well as the concentration ratio between p-O-TPE and the acceptor PDI-Sil, we prepared three series of samples based on either p-O-TPE, PDI-Sil, or their mixtures incorporated into dU(600). In all samples, p-O-TPE is homogeneously mixed throughout the ureasil as a composite, whereas PDI-Sil is covalently grafted to the siliceous domains through the hydrolysis and co-condensation between the triethoxysilyl groups of PDI-Sil and d-UPTES during the sol–gel process.…”

The Importance of Microstructure in Determining Polaron Generation Yield in Poly(9,9-dioctylfluorene)

“…[28][29][30][31][32][33][34] In recent years, a growing number of PFO derivatives and related polyfluorenes have also shown a similar β-phase conformation. [35][36][37][38][39][40][41][42][43][44] Polymer chain segments adopting a β-phase conformation exhibit a planarised interunit torsion angle of ≈ 180°, in comparison to the majority in-plane isotropic 'glassy-phase' segments which adopt a much wider range of more twisted torsion angles of ≈ 120-140°. 30,45 While for β-phase the alternation of side chains leads to formation of a 21 helix, the direction of side chain extension does not necessarily alternate for the glassy-phase.…”

Siloxanes—Versatile Materials for Surface Functionalisation and Graft Copolymers

“…These ureasils were designed in order to alter the molecular organisation of the conjugated polyfluorene chains and, consequently, their various optoelectronic properties. Although the photoluminescence properties of the polyfluorene copolymer were indeed found to change over the course of the abovementioned reactions, it should be noted that the photoluminescence intensity also decreased significantly and that the effect of this modification on the conductivity of the materials was not investigated [ 42 ].…”