Université de Fribourg

Orientational behavior of ellipsoidal silica-coated hematite nanoparticles integrated within an elastomeric matrix and its mechanical reinforcement

Sánchez-Ferrer, Antoni ; Mezzenga, Raffaele ; Dietsch, Hervé

In: Macromolecular Chemistry and Physics, 2011, vol. 212, no. 6, p. 627–634

The mechanical and orientational properties of IOENs consisting of integrated ellipsoidal SCH spindle-type nanoparticles within an elastomeric matrix are reported. The influence of the SCH surface chemistry, leading either to dispersed nanoparticles or crosslinked nanoparticles within the surrounding elastomeric matrix, is studied by mechanical uniaxial deformation (stress-strain) and SAXS...

Université de Fribourg

Inorganic–organic elastomer nanocomposites from integrated ellipsoidal silica-coated hematite nanoparticles as crosslinking agents

Sánchez-Ferrer, Antoni ; Reufer, Mathias ; Mezzenga, Raffaele ; Schurtenberger, Peter ; Dietsch, Hervé

In: Nanotechnology, 2010, vol. 21, no. 18, p. 185603

We report on the synthesis of nanocomposites with integrated ellipsoidal silica-coated hematite (SCH) spindle type nanoparticles which can act as crosslinking agents within an elastomeric matrix. Influence of the surface chemistry of the hematite, leading either to dispersed particles or crosslinked particles to the elastomer matrix, was studied via swelling, scattering and microscopy...

Université de Fribourg

Secondary structure-induced micro- and macrophase separation in rod-coil polypeptide diblock, triblock, and star-block copolymers

Sánchez-Ferrer, Antoni ; Mezzenga, Raffaele

In: Macromolecules, 2010, vol. 43, no. 2, p. 1093–1100

Ten novel rod−coil block copolymers based on poly(γ-benzyl-l-glutamate) (PBLG), rod block, and poly(propylene oxide) (PPO), coil block, have been synthesized, and the influence on their secondary structure and solid-state organization have been studied in terms of their architecture (diblock, triblock, or star-block), molecular weight of the polymer coil block (from 2 to 5 kDa), and volume...

Université de Fribourg

Thermal and mechanical properties of new main-chain liquid-crystalline elastomers

Sánchez-Ferrer, Antoni ; Finkelmann, Heino

In: Molecular Crystals and Liquid Crystals, 2009, vol. 508, p. 348-356

New Main-Chain Liquid-Crystalline Elastomers (MCLCEs) were synthesised based on reacting vinyloxy-terminated mesogens under hydrosilylation conditions with a flexible crosslinker. These main-chain systems showed smectic and nematic mesophases and their anisotropic properties were mechanically and thermally analysed as function of the crosslinking density. Due to the suitable chemistry used in...

Université de Fribourg

Photo-crosslinked side-chain liquid-crystalline elastomers for microsystems

Sánchez-Ferrer, Antoni ; Fischl, Tamás ; Stubenrauch, Mike ; Wurmus, Helmut ; Hoffmann, Martin ; Finkelmann, Heino

In: Macromolecular Chemistry and Physics, 2009, vol. 210, no. 20, p. 1671-1677

Photo-crosslinkable side-chain liquid-crystalline polymers (LCPs) containing photoreactive benzophenone cores are synthesized in order to obtain their corresponding side-chain liquid-crystalline elastomers (LCEs). This strategic synthesis allows thin elastomeric films and their integration into microsystems for actuators and micromachines to be obtained. As an example of this principle, a gripper...

Université de Fribourg

Mechanical deformations in smectic-C main-chain liquid-crystalline elastomers

Sánchez-Ferrer, Antoni ; Finkelmann, Heino

In: Molecular Crystals and Liquid Crystals, 2009, p. 357-366

A novel crosslinked smectic-C Main-Chain Liquid-Crystalline Elastomer (MCLCE) has been synthesized by polycondensation of vinyloxy-terminated mesogens, tetramethyldisiloxane and pentamethylpentaoxapentasilecane. The introduction of the functional vinyloxy group allows the synthesis of well-defined networks having low soluble content and good mechanical properties. Networks having a macroscopic...

Université de Fribourg

Liquid crystal elastomer–nanoparticle systems for actuation

Chambers, Martin ; Finkelmann, Heino ; Remškar, Maja ; Sánchez-Ferrer, Antoni ; Zalar, Boštjan ; Žumer, Slobodan

In: Journal of Materials Chemistry, 2009, vol. 19, p. 1524 - 1531

Liquid crystal elastomers (LCE) are currently of great interest due to conjoining of mesogenic ordering and rubber elasticity, exhibited in their large spontaneous thermally stimulated changes in shape. It has been shown that nanoparticles (nanotubes, photo-isomerisable dyes, magnetic nanoparticles) can be incorporated into these LCE networks to create a more sensitive network to external stimuli...