Christopher Tollan

CIC nanoGUNE Consolider · Electron Microscopy (CIC06)

Liquid-phase transmission electron microscopy is a burgeoning experimental technique for monitoring nanoscale dynamics in a liquid environment, increasingly employing microfluidic reactors to control the composition of the sample solution. Current challenges comprise fast mass transport dynamics inside the central nanochannel of the liquid cell, ty...

Liquid Phase-Transmission Electron Microscopy research increasingly relies on liquid flow reactors to monitor nanoscale dynamics. Current challenges comprise fast mass transport dynamics inside the central nanochannel of the liquid cell, typically flow cells , and reliable fixation of the specimen in the limited imaging area. In this work, we prese...

Liquid-Phase Transmission Electron Microscopy (LP-TEM) offers the opportunity to study nanoscale dynamics of phenomena related to materials and life science in a native liquid environment and in real time. Until now, the opportunity to control/induce such dynamics by changing the chemical environment in the liquid flow cell (LFC) has rarely been ex...

Solution-phase self-assembly of anisotropic nanoparticles into complex 2D and 3D assemblies is one of the most promising strategies toward obtaining nanoparticle-based materials and devices with unique optical properties at the macroscale. However, controlling this process with single-particle precision is highly demanding, mostly due to insufficie...

The physical properties of polymers can be significantly altered by blending them with inorganic components. This can be done during the polymerization process, but also by post-processing of already shaped materials, for example through coating by atomic layer deposition (ALD) or hybridizing through vapor phase infiltration (VPI), both of which ar...

We explore electrodeposited ordered arrays of Fe, Ni and Co nanorods embedded in anodic alumina membranes as a source of intense magnetic stray field gradients localized at the nanoscale. We perform a multiscale characterization of the stray fields using a combination of experimental methods (Magneto-optical Kerr effect, Virtual Bright Field Differ...

Polaritons—hybrid light–matter excitations—enable nanoscale control of light. Particularly large polariton field confinement and long lifetimes can be found in graphene and materials consisting of two-dimensional layers bound by weak van der Waals forces1,2 (vdW materials). These polaritons can be tuned by electric fields3,4 or by material thicknes...

Spin-to-charge current interconversions are widely exploited for the generation and detection of pure spin currents and are key ingredients for future spintronic devices including spin-orbit torques and spin-orbit logic circuits. In the case of the spin Hall effect, different mechanisms contribute to the phenomenon and determining the leading contr...

Spin-to-charge current interconversions are widely exploited for the generation and detection of pure spin currents and are key ingredients for future spintronic devices including spin-orbit torques and spin-orbit logic circuits. In case of the spin Hall effect, different mechanisms contribute to the phenomenon and determining the leading contribut...

Efficient doping of organic semiconductors is an important prerequisite for the fabrication of high performance organic electronic devices. In this work, we describe a novel single precursor low-temperature (70 °C) vapor phase infiltration (VPI) process to dope poly(3-hexyl)thiophene (P3HT). The infiltration is performed with the metal containing a...

Graphene is an attractive material for its physicochemical properties, but for many applications only chemically synthesized forms such as graphene oxide (GO) and reduced graphene oxide (rGO) can be produced in sufficient amounts. If considered as electrode material, the intrinsic defects of GO or rGO may have negative influence on the conductivity...

Coalescence and interdiffusion during film formation of waterborne polymers stabilized by commercial high T g alkali-soluble resins (ASRs) were evaluated through environmental scanning electron microscopy and fluorescence resonance energy transfer. The observed effects were used to justify the mechanical properties. The presence of a hard barrier b...

The role of the growth conditions in the spin transport properties of silver (Ag) have been studied by using lateral spin valve structures. By changing the deposition conditions of Ag from polycrystalline to epitaxial growth, we have observed a considerable enhancement of the spin diffusion length, from $\lambda_{Ag}$ = 449 $\pm$ 30 to 823 $\pm$ 59...

Surfactant free 50 wt% solids content latexes were synthesized by means of miniemulsion copolymerization of vinyl acetate and Veova10 using modest amount (<= 10 wt% based on monomer) of silica as a Pickering stabilizer. The silica was surface modified with PEO chains to improve its adsorption on the miniemulsion droplets. Coagulum free latexes were...

A novel pathway is presented to transfer and embed functional patterned magnetic nanostructures into flexible and stretchable polymeric membranes. The geometrical and magnetic properties are maintained through the process, realized even directly inside a microfluidic channel. These results pave the way to the realization of smart biomedical systems...

A new methodology for quantitative characterization of the coalescence process of waterborne polymer dispersion (latex) particles by environmental scanning electron microscopy (ESEM) is proposed. The experimental setup has been developed to provide reproducible latex monolayer depositions, optimized contrast of the latex particles, and a reliable r...

The novel application of gold and silver nanorods as irreversible thermochromic dyes in polymeric ionic liquid (PIL) nanocomposites is proposed here. These materials have been synthesized by anion exchange of an imidazolium-based PIL in a solution that also contained gold nanorods. This resulted in the entrapment of the nanoobjects within a solid p...

An effective strategy is presented to produce hydrophobic and water-resistant poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) films by replacing the cations associated with the sulfonatepolyanion by large organic cations. Addition of specific ionic liquids (ILs) bearing large cations to the commercial PEDOT:PSS aqueous dispersio...

A method has been developed for synthesising a series of soluble C60 containing polymers which have the characteristic photophysical properties of monosubstituted-fullerene derivatives. The strategy employed required that first a suitably derivatised mono-fulleropyrrolidine was prepared and characterised which was then subsequently reacted with an...

The synthesis and characterisation of gold nanorods have been carried out by reduction of the gold salt HAuCl4. This has been done using a single reducing agent, acetylacetone, rather than the two reducing agents, sodium borohydride and ascorbic acid, normally required by standard wet chemistry methods of gold nanorod formation. Using this novel me...