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Université de Fribourg

Functional columnar liquid crystalline phases from ionic complexes of dendronized polymers and sulfate alkyl tails

Canilho, Nadia ; Kasëmi, Edis ; Schlüter, Dieter A. ; Ruokolainen, Janne ; Mezzenga, Raffaele

In: Macromolecular Symposia, 2008, vol. 270, no. 1, p. 58 - 64

We describe how cationic dendronized polymers of generations 1, and 2 and anionic monoalkyl tails can be combined by supramolecular ionic complexation into comb-like liquid crystalline polymers. The final structures in bulk of these supramolecular complexes were studied by differential scanning calorimetry (DSC), cross-polarized optical microscopy (CPOM), small angle x-rays scattering (SAXS) and...

Université de Fribourg

Self-assembly of rod-coil block copolymers for photovoltaic applications

Sary, Nicolas ; Rubatat, Laurent ; Brochon, Cyril ; Hadziioannou, Georges ; Mezzenga, Raffaele

In: Macromolecular Symposia, 2008, vol. 268, no. 1, p. 28-32

Two different approaches to obtain electron donor-acceptor interfaces via self-assembly of block copolymer systems are discussed, where the donor domains are formed by a π-conjugated rod-like polymer and the acceptor domains result from a coiled polymer modified by C₆₀ fullerenes. In the first strategy, C₆₀ is chemically grafted onto the coil polymer, typically a statistical...

Université de Fribourg

Self-assembly of rod-coil block copolymers from weakly to moderately segregated regimes

Sary, Nicolas ; Brochon, Cyril ; Hadziioannou, G. ; Mezzenga, Raffaele

In: The European Physical Journal E, 2007, vol. 24, no. 4, p. 379-384

We report on the self-assembly behaviour of two homologue series of rod-coil block copolymers in which, the rod, a π -conjugated polymer, is maintained fixed in size and chemical structure, while the coil is allowed to vary both in molecular weight and chemical nature. This allows maintaining constant the liquid crystalline interactions, expressed by Maier-Saupe interactions, ω , while...

Université de Fribourg

Self-consistent field theory for lipid-based liquid crystals: Hydrogen bonding effect

Lee, Won Bo ; Mezzenga, Raffaele ; Fredrickson, Glenn H.

In: The Journal of Chemical Physics, 2008, vol. 128, no. 7, p. 074504

A model to describe the self-assembly properties of aqueous blends of nonionic lipids is developed in the framework of self-consistent field theory (SCFT). Thermally reversible hydrogen bonding between lipid heads and water turns out to be a key factor in describing the lyotropic and thermotropic phase behavior of such systems. Our model includes reversible hydrogen bonding imposed in the context...

Université de Fribourg

Supramolecular routes towards liquid crystalline side-chain polymers

Hammond, Matthew R. ; Mezzenga, Raffaele

In: Soft Matter, 2008, vol. 4, p. 952-961

Supramolecular attachment of mesogenic or non-mesogenic side chains to polymer backbones can result in the formation of liquid crystalline morphologies. The various parameters that can be tuned in order to achieve these morphologies, such as the type of non-covalent bonding chemistry (hydrogen bonding, ionic bonding, metal coordination, π–π interactions), the polymeric template architecture,...

Université de Fribourg

Self-organization on multiple length scales in "hairy rod"-coil block copolymer supramolecular complexes

Hammond, Matthew R. ; Klok, Harm-Anton ; Mezzenga, Raffaele

In: Macromolecular Rapid Communications, 2008, vol. 29, no. 4, p. 299-303

A peptide-synthetic hybrid block copolymer, poly(ethylene oxide)-block-poly(L-glutamic acid), is shown to form supramolecular complexes with primary alkylamines of varying alkyl chain lengths (8 to 18 methylene units) in organic solvents via acid-base proton transfer and subsequent ionic bonding. The peptidic block being in the α-helical conformation, these materials behave as...

Université de Fribourg

Thermotropic ionic liquid crystals via self-assembly of cationic hyperbranched polypeptides and anionic surfactants

Canilho, Nadia ; Scholl, Markus ; Klok, Harm-Anton ; Mezzenga, Raffaele

In: Macromolecules, 2008, vol. 40, no. 23, p. 8374 -8383

This work describes the dilute solution and solid-state structure of polyelectrolyte complexes generated from hyperbranched polylysine (HBPL) and various anionic, sodium alkyl sulfate surfactants. In dilute solution, the radius of gyration (Rg) of the HBPL and HBPL-surfactant complexes was determined in the Guinier regime in good solvent conditions by means of small-angle X-ray...

Université de Fribourg

Self-assembly of poly(diethylhexyloxy-p-phenylenevinylene)-b-poly(4-vinylpyridine) rod-coil block copolymer systems

Sary, Nicolas ; Rubatat, Laurent ; Brochon, Cyril ; Hadziioannou, Georges ; Ruokolainen, Janne ; Mezzenga, Raffaele

In: Macromolecules, 2007, vol. 40, no. 19, p. 6990 -6997

We describe the synthesis, the morphology, and self-assembly behavior of semiconducting poly(4-vinylpyridine-b-diethylhexyloxy-p-phenylenevinylene) (P4VP-b-PPV) rod-coil block copolymer systems. Three different block copolymers with 55%, 80%, and 88% coil volume fraction were synthesized by convergent anionic polymerization in THF using lithium α-methylstyrene as initiator....

Université de Fribourg

Structural and rheological investigation of Fd3m inverse micellar cubic phases

Pouzot, Matthieu ; Mezzenga, Raffaele ; Leser, Martin E. ; Sagalowicz, Laurent ; Guillot, Samuel ; Glatter, Otto

In: Langmuir, 2007, vol. 23, no. 19, p. 9618-9628

In the present study we demonstrate that a bulk inverse micellar cubic phase of Fd3m structure can be obtained by adding a hydrophobic component, such as the food-grade limonene, to the binary system monolinolein/water in a well-defined composition. The Fd3m structure studied in this work had a very slow kinetics of formation, as a consequence of partitioning of water...

Université de Fribourg

Real space imaging and molecular packing of dendronized polymer-lipid supramolecular complexes

Canilho, Nadia ; Kasëmi, Edis ; Schlüter, Dieter A. ; Ruokolainen, Janne ; Mezzenga, Raffaele

In: Macromolecules, 2007, vol. 40, no. 21, p. 7609 -7616

The present work describes the molecular structure and the topology in real space of self-assembled comblike liquid crystalline polymers based on supramolecular ionic complexation of dendronized polymers and lipids. The molecular organization was studied as a function of the generation of the dendronized polymers and the length of the lipid tails, both parameters being known to strongly influence...