Negar Ghasdian

Synthesis of Prussian Blue Coordination Polymer Nanocubes via Confinement of the Polymerization Field Using Miniemulsion Periphery Polymerization (MEPP)

Miniemulsion periphery polymerization (MEPP) has been used for the synthesis of Prussian blue (PB) nanocubes. Pentacyano ferrate functionalized surfactant in combination with a co-surfactant containing 4-(dimethylamino)-pyridine (DMAP) or OH end groups in lieu of ferrate functionality (EPE-DMAP or EPE-OH) were used to prepare a miniemulsion system comprising 20 wt.-% toluene and 0.5 wt.-% total surfactant. On addition of Fe(3+) to the miniemulsion, metal coordination polymerization occurred with nanocubes generated when the ratio of EPE-Fe:EPE-DMAP (or EPE-OH) was 60:40 (w/w). The resulting nanocubes are apparently amorphous. Particles with irregular shape have been observed on reacting EPE-Fe and Fe(3+) directly in water, thus suggesting that confinement of the polymerization field on the periphery of the miniemulsion droplets is a primary factor in the formation of cubic structures.

ABC triblock copolymer micelles: Spherical versus worm-like micelles depending on the preparation method

Well-defined ABC triblock copolymers based on two hydrophilic blocks, A and C, and a hydrophobic block B are synthesized and their self-assembly behavior is investigated. Interestingly, at the same solvent, concentration, pH, and temperature, different shape micelles are observed, spherical and worm-like micelles, depending on the preparation method. Specifically, spherical micelles are observed with bulk rehydration while both spherical and worm-like micelles are observed with film rehydration.

Novel “core-first” star-based quasi-model amphiphilic polymer networks

Novel quasi-model networks based on “core-first” star (co)polymers have been synthesised. The polymeric networks (gels) were based on the hydrophilic, thermo- and pH-responsive 2-(dimethylamino)ethyl methacrylate (DMAEMA) and the non-ionic, hydrophobic methyl methacrylate (MMA). Specifically two homopolymer networks and three amphiphilic polymer networks were synthesised based on two block and one statistical “core-first” star copolymers. The precursors to and the extractables of the networks were characterised using Gel Permeation Chromatography and proton Nuclear Magnetic Resonance to determine the molecular weight, polydispersity and composition. The degrees of swelling (DSs) of the networks were then determined in both aqueous and organic solvents. The DSs in organic solvents and non-acidic water were dependant only on the composition of the conetworks while the DSs in acidic water were also affected by the architecture of the conetworks. Finally the networks were evaluated in terms of their ability to absorb and deliver hydrophilic and hydrophobic compounds that were used as “model drugs” and interestingly it was observed that the architecture of the networks, and not just the composition of the networks, affected the release of the compounds.

Tailoring the optical properties of poly(3-hexylthiophene) by emulsion processing using polymeric macrosurfactants

Here we demonstrate that the use of macrosurfactants in the production of poly(3-hexylthiophene) (P3HT):water dispersion allows to drastically change the semiconductors molecular aggregation, leading to pronounced H- or J-like behaviour depending on the macrosurfactant used and the conditions selected to produce the dispersions. No correlation with the particle size and optical response is found, indicating that it is the pre-assembly in the initial emulsion and possibly additional features such as the thermoresponsiveness of one of the macrosurfactants that lead to the specific molecular arrangement of the P3HT. Considering the broad variety of macrosurfactants that can be synthesised based already on the building blocks (co-polymer units) used here, it is clear that this approach can widen the tool box towards structural control of organic semiconductors, and macromolecular materials especially.