Poly(p-phenylenevinylene)s (PPVs) with single reactive end groups have been prepared with high molecular weights, narrow polydispersities (ĐM) and excellent end functionality (f). PPVs functionalised with α-bromoester end groups are effective macroinitiators in the atom transfer radical polymerisation (ATRP) of methyl methacrylate (MMA).

A range of stable emulsions of spherical and rod-like conjugated polymer nanoparticles (CPN) were synthesized via Suzuki−Miyaura cross-coupling reactions of 9,9-dioctylfluorene-2,7-diboronic acid bis(1,3-propanediol) ester with a number of different dibromoarene monomers in xylene, stabilized in water by the nonionic surfactant, Triton X-102. High molar mass poly(9,9-dioctylfluorene) (PF8), poly(9,9-dioctylfluorene-alt-benzothiadiazole) (PF8BT), poly(9,9-dioctylfluorene-alt-4-sec-butylphenyldiphenylamine) (PF8TAA) and poly(9,9-dioctylfluorene-alt-bithiophene) (PF8T2) emulsions were obtained, at high overall conjugated polymer concentrations (up to 11,000 ppm), in the presence of the palladium complex, (IPr*)PdCl2(TEA) and base, tetraethylammonium hydroxide, in nitrogen atmosphere at 30 °C after 24–48 h. TEM analysis of the PF8 and PF8T2 emulsions revealed regular rod-like structures, up to 200 nm in length with aspect ratios of 4–5. PF8BT and PF8TAA formed spherical particles with diameters of between 20–40 nm in TEM analysis. UV–vis absorption spectra of the PF8 emulsions indicated high levels of ordered β-phase configuration (9–10%) in their respective nanoparticles. Absolute photoluminescence quantum yields (Φ) of 21–25% were recorded for these emulsions.

Suzuki cross-coupling polymerisation of aryldibromides and aryldiboronate esters in a sodium dodecyl sulfate (SDS)-stabilised miniemulsion provides a versatile and direct route to fluorescent conjugated polymer nanoparticles (CPNs). These nanoparticles have a conjugated backbone based on poly(9,9-dioctylfluorene) (PFO), however, significant structural diversity is introduced by incorporation of electron withdrawing, heterocyclic comonomers (5-50 mol. %) in order to tune the emission wavelengths from blue to far-red/near-infrared. The robust nature of the polymerisation methodology allows for rapid assessment of the relationship between polymer composition, chain morphology and optical properties of the resultant CPNs. Moreover, the CPNs (after a simple and rapid purification step) can be used directly in fluorescence-based intracellular labelling experiments (in HCT116 cells), in which they display low cytotoxicity at biologically-useful concentrations.

Polyfluorenes with pendant alkoxysilyl groups have been used to prepare inorganic-organic composite nanoparticles (diameter ¼ 80-220 nm) in which the conjugated polymer is dispersed within a silica matrix. Preparation of these nanoparticles is achieved by simultaneous nanoprecipitation of the conjugated polymer and hydrolysis/crosslinking of the alkoxysilyl groups under basic conditions. The composition of the nanocomposites is controlled by addition of an alkoxysilane monomer, tetramethylorthosilicate. The hybrid nanoparticles form highly stable dispersions in water and buffer (pH 9.2). The size of the nanoparticles can be tuned by varying the amount of the alkoxysilane monomer added during the nanoprecipitation process. Increasing the relative amount of alkoxysilane monomer also increases the proportion of polyfluorene chains that adopt the higher energy b-phase conformation within the resultant nanoparticles. Nanoparticles with the highest silica content were found to have increased photoluminescence quantum yields. This work provides a controllable method for optimisation of the photophysical properties of light-emitting conjugated polymer nanoparticles via a simple aqueous processing technique.

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