Monodisperse conjugated polymer particles by Suzuki-Miyaura dispersion polymerization

The self-assembly of colloidal building blocks into complex and hierarchical structures offers a versatile and powerful toolbox for the creation of new photonic and optoelectronic materials. However, well-defined and monodisperse colloids of semiconducting polymers, which would form excellent building blocks for such self-assembled materials, are not readily available. Here we report the first demonstration of a Suzuki–Miyaura dispersion polymerization; this method produces highly monodisperse submicrometer particles of a variety of semiconducting polymers. Moreover, we show that these monodisperse particles readily self-assemble into photonic crystals that exhibit a pronounced photonic stopgap

Novel vinyl ether functionalized fluorene polymers for active incorporation into common photoresist matrices

A novel vinyl ether functionalized fluorene monomer was prepared to produce a series of fluorene-based polymers with different emitter units to cover emission in the visible spectrum whilst retaining the same main absorption profile. The vinyl ether functionality allows for active incorporation of the light emitting polymers into standard vinyl ether and glycidyl ether photoresist materials. This enables photopatterning of light emitting structures for application in UV down-conversion, waveguiding and for lasing media

Well-defined temperature-sensitive surfactants for controlled emulsion coalescence

In a variety of applications, emulsion formulations are required, which exhibit excellent shelf stability yet can be broken or perform phase inversion at a desired time. Here we approach these contradictory constraints through the synthesis of well-defined thermoresponsive surfactants based on di(ethylene glycol)methacrylate and poly(ethylene glycol)methacrylate using Atom Transfer Radical Polymerization. The surfactants show a Lower Critical Solution Temperature (LCST) of approximately 34 °C, independent of molecular weight, which is ascertained by both Differential Scanning Calorimetry as well as Dynamic Light Scattering. Below the LCST, the surfactants stabilize the emulsions for at least four months. Above this temperature the hydrophilic block collapses and coalescence between the emulsion droplets occurs; this leads to demixing of the sample within several minutes. We reveal the mechanism for the temperature-triggered coalescence by measurements of the temperature-dependent interfacial tension and by studying the interfacial morphology of surfactant-covered emulsion droplets

Programmable co-assembly of oppositely charged microgels

Here we report the development of an aqueous, self-assembling system of oppositely charged colloids leading towards particle arrangements with controlled order. The colloidal system consists of two types of particles, each consisting of refractive index matched colloidal core–shell microgel particles, which are either negatively charged or amphoteric. By slowly decreasing the pH of our system below the isoelectric point of the amphoteric particles, changing their net charge from negative to positive, the co-assembly of the colloids is induced. By using different buffer concentrations, we gain temporal and kinetic control over the acidification process and thus the ability to program the co-assembly of the two particles species

Conjugated polymer shells on colloidal templates by seeded Suzuki-Miyaura dispersion polymerization

The self-assembly of colloidal conjugated polymers presents a versatile and powerful oute towards new functional optoelectronic materials and devices. However, this strategy relies on the existence of chemical protocols to prepare highly monodisperse colloids of conjugated polymers in high yields. Here, a recently developed Suzuki–Miyaura dispersion polymerization method is adopted to synthesize core–shell particles, in which a conjugated polymer shell is grown onto non-conjugated organic and inorganic colloidal templates. By chemically anchoring aryl halide groups at the particle surface, a conjugated polymer shell can be attached to a wide variety of organic and inorganic microparticles. In this way, both spherical and non-spherical hybrid conjugated polymer particles are prepared, and it is shown that the method can be applied to a variety of conjugated polymers. This new method offers independent control of the size, shape and photophysical properties of these novel conjugated polymer particles

Star-shaped oligofluorene nanostructured blend materials: controlled micro-patterning and physical characteristics

Star-shaped oligofluorene consists of highly-fluorescent macromolecules of considerable interest for organic electronics. Here, we demonstrate controlled micro-patterning of these organic nanostructured molecules by blending them with custom-synthesized photo-curable aliphatic polymer matrices to facilitate solventless inkjet printing. The printed microstructures are spherical with minimum dimensions of 12 μm diameter and 1 μm height when using a cartridge delivering ∼1 pL droplets. We evaluate the physical characteristics of the printed structures. Photoluminescence studies indicate that the blend materials possess similar fluorescence properties to neat materials in solid films or toluene solution. The fluorescence lifetime consists of two components, respectively 0.68±0.01 ns (τ 1) and 1.23±0.12 ns (τ 2). This work demonstrates that inkjet printing of such blends provides an attractive method of handling fluorescent nano-scaled molecules for photonic and optoelectronic applications