Methods
- X-ray scattering
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- Small- and wide-angle X-ray scattering for polymers and particles in solution;
- X-ray reflectometry
- And grazing incidence techniques for thin, semi-crystalline films.
- Particle analysis
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- Dynamic light scattering and zeta potential measurements of particles in solution.
- Laser light diffraction and image analysis for µm-sized particles.
- Determination of solution viscosity of polymers.
- Electrochemical characterization
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- Potentiostat / Galvanostat / Impedance Analysis,
- Electrochemical impedance spectroscopy;
- Cyclic voltammetry, DC and low frequency AC probing;
- Potentiometric titration
Expertise
- Size determination of polymers and particles in solution
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Understanding the size of polymers and particles in solution is crucial for a variety of applications, ranging from drug delivery to material science. The size influences the properties of materials, including their reactivity, solubility, and stability. Various techniques can be employed to characterize particle sizes, such as DLS, TEM, SEC or AFM. Within the cluster “scattering and interface analysis” techniques based on dynamic light scattering (DLS) are utilized. In DLS the fluctuation in intensity of the scattered light is analyzed to determine the diffusion coefficient of polymer particles. It is particularly effective for particles in the nanometer range and provides information about size distribution and polydispersity.
- Zeta-potential and electrokinetics
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Zeta potential provides insight into the electrostatic environment surrounding dispersed particles. It is defined as the electrical potential at the slipping plane, which is the boundary layer between a particle and the surrounding liquid. A polymer particle in liquid acquires a surface charge by adsorption of ions or other charged species, which creates an electric double layer, consisting of a stationary layer of ions bound to the particle surface and a mobile layer of ions in the surrounding solution. In electrokinetical methods the movement of charged particles in an electric field are analyzed. Hereby, electroosmosis and -phoresis can help determine the size and distribution of particles in a suspension, but can also provide insight into ion movement in polymer matrices.
- Determination of redox potentials and electrochemical stability
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Electrochemical techniques, such as cyclic voltammetry or potentiometry, can be used to determine redox potentials and electrochemical stability of polymer materials. Hereby, potentiometry measures the voltage of a half-cell relative to a reference electrode, while cyclic voltammetry involves sweeping the potential of a working electrode and measuring the resulting current. Analyzing the peaks in both methods relative to a standard reference electrode (e.g. Ag/AgCl) can help determine redox potentials. To assess the electrochemical stability of a compound scan rate variation, multiple cycles and/or the expansion of the potential range in cyclic voltammetry are applied.
- Determination of functional groups in water and organic solvents
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Acid-base titrations or redox titrations are utilized for the determination of functional groups in water or organic solvents. For known target functional groups a titration experiment can be performed. The change in pH or potential is monitored until the endpoint of titration by adding the titrant to the sample solution under stirring. From the volume of the titrant used the concentration of functional groups can be determined.
- Analysis of crystallinity in particles and films
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Crystalline or semi-crystalline materials have a well-defined, ordered structure, which influences their mechanical strength, thermal stability, optical properties, and electrical conductivity. X-ray diffraction (XRD), also called wide angle scattering (WAXS) provides information about the crystal structure, phase composition, and degree of crystallinity by measuring the diffraction patterns of X-rays interacting with polymer material in bulk form, in solution or in films. Especially for very thin films grazing incidence wide-angle scattering (GIWAXS) is applied to enhance the illuminated sample area for X-ray diffraction analysis.
- Evaluation of thin film density and thickness
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One of the techniques to evaluate thin film our multilayer thickness is X-ray reflectometry (XRR). XRR involves directing X-rays at a thin film and measuring the intensity of reflected X-rays as a function of the angle of incidence. By full modeling of the XRR curve detailed information about film thickness, density, and roughness can be obtained.
Contact Scattering Cluster
