8 research outputs found
Vibrational Spectroscopy and Spectral Imaging Techniques – Special Applications in the Polymer Science
Crystallographic structure and morphology of bithiophene-fluorene polymer nanocrystals
Nanocrystals of the polymer poly(9,9-dioctylfluorenyl-co-bithiophene) (F8T2) with a molecular weight of 3.2 kg/mol are grown in a para-xylene solution. The typical morphology of the crystals is needle like with typical widths of 50 nm and lengths of about 200 nm. The crystal structure and morphology are stable up to a temperature of 353 K. The structure solution is obtained by x-ray powder diffraction (XRD) pattern with data modelling by a stochastic global optimization procedure which allows simultaneous indexing and molecular packing determination. Final Rietveld refinement was applied on the most promising crystal structure with a = 1.376 nm, b = 3.105 nm, c = 2.690 nm and ß = 109.5° within the space group C2/c choosing the polymer backbone parallel to the b-axis. The structural motifs of the molecular packing could be identified: aromatic units within a single polymer chain are slightly bent relative to the chain axis, octyl side chains are aligned along the polymer backbone and aromatic units of neighbouring molecules display a strong tendency to stack parallel to each other. XRD results of F8T2 with a molecular weight of 19 kg/mol reveal the same peak positions compared to the 3.2 kg/mol material, showing that both materials crystallise similarly and can be described by the same crystallographic unit cell. The smaller peak intensities together with the broader peak widths, however, show that the ability of crystal formation for the 19 kg/mol material is reduced
Adsorption Studies of Organophosphonic Acids on Differently Activated Gold Surfaces
In this study, the formation of self-assembled
monolayers consisting
of three organophosphonic acids (vinyl-, octyl-, and tetradecylphosphonic
acid) from isopropanol solutions onto differently activated gold surfaces
is studied in situ and in real time using multiparameter surface plasmon
resonance (MP-SPR). Data retrieved from MP-SPR measurements revealed
similar adsorption kinetics for all investigated organophosphonic
acids (PA). The layer thickness of the immobilized PA is in the range
of 0.6–1.8 nm corresponding to monolayer-like coverage and
correlates with the length of the hydrocarbon chain of the PA molecules.
After sintering the surfaces, the PA are irreversibly attached onto
the surfaces as proven by X-ray photoelectron spectroscopy and attenuated
total reflection infrared and grazing incidence infrared spectroscopy.
Potential adsorption modes and interaction mechanisms are proposed
Reducing shadowing losses with femtosecond-laser-written deflective optical elements in the bulk of EVA encapsulation
Tunable Semicrystalline Thin Film Cellulose Substrate for High-Resolution, <i>In-Situ</i> AFM Characterization of Enzymatic Cellulose Degradation
In the field of enzymatic cellulose
degradation, fundamental interactions between different enzymes and
polymorphic cellulose materials are of essential importance but still
not understood in full detail. One technology with the potential of
direct visualization of such bioprocesses is atomic force microscopy
(AFM) due to its capability of real-time <i>in situ</i> investigations
with spatial resolutions down to the molecular scale. To exploit the
full capabilities of this technology and unravel fundamental enzyme–cellulose
bioprocesses, appropriate cellulose substrates are decisive. In this
study, we introduce a semicrystalline-thin-film-cellulose (SCFTC)
substrate which fulfills the strong demands on such ideal cellulose
substrates by means of (1) tunable polymorphism via variable contents
of homogeneously sized cellulose nanocrystals embedded in an amorphous
cellulose matrix; (2) nanoflat surface topology for high-resolution
and high-speed AFM; and (3) fast, simple, and reproducible fabrication.
The study starts with a detailed description of SCTFC preparation
protocols including an in-depth material characterization. In the
second part, we demonstrate the suitability of SCTFC substrates for
enzymatic degradation studies by combined, individual, and sequential
exposure to TrCel6A/TrCel7A cellulases (<i>Trichoderma reesei</i>) to visualize synergistic effects down to the nanoscale
Tunable Semicrystalline Thin Film Cellulose Substrate for High-Resolution, <i>In-Situ</i> AFM Characterization of Enzymatic Cellulose Degradation
In the field of enzymatic cellulose
degradation, fundamental interactions between different enzymes and
polymorphic cellulose materials are of essential importance but still
not understood in full detail. One technology with the potential of
direct visualization of such bioprocesses is atomic force microscopy
(AFM) due to its capability of real-time <i>in situ</i> investigations
with spatial resolutions down to the molecular scale. To exploit the
full capabilities of this technology and unravel fundamental enzyme–cellulose
bioprocesses, appropriate cellulose substrates are decisive. In this
study, we introduce a semicrystalline-thin-film-cellulose (SCFTC)
substrate which fulfills the strong demands on such ideal cellulose
substrates by means of (1) tunable polymorphism via variable contents
of homogeneously sized cellulose nanocrystals embedded in an amorphous
cellulose matrix; (2) nanoflat surface topology for high-resolution
and high-speed AFM; and (3) fast, simple, and reproducible fabrication.
The study starts with a detailed description of SCTFC preparation
protocols including an in-depth material characterization. In the
second part, we demonstrate the suitability of SCTFC substrates for
enzymatic degradation studies by combined, individual, and sequential
exposure to TrCel6A/TrCel7A cellulases (<i>Trichoderma reesei</i>) to visualize synergistic effects down to the nanoscale