Muller, Surface Forces (Consultants Bureau, New York, 1987). Galembeck, Colloids Surf., A 144 (1–3), 207 (1998).ī. A polystyrene (PS)/poly(butyl acrylate) (PBA) composite emulsion was produced by seeded emulsion polymerization of butyl acrylate (BA) with PS seed particles which were prepared by emulsifier-free polymerization of styrene with potassium persulfate (KPS) under a nitrogen atmosphere at 70C for 24 h with stirring at 60 rpm and swelled with the BA monomer in an ethanol/water medium. Ito, Langmuir 1 (1), 176 (1985).Ĭolloids and Colloid Assemblies, Ed. Ordering and Phase Transitions in Charged Colloids, Ed. In the theta state, the polymer behaves exactly as an ideal chain, which makes it easier to determine further parameters, such as the root mean square end-to-end distance.P. Determining the theta state of a polymer-solvent system is beneficial for further characterization of the sample. As the 2 nd virial coefficient is temperature-dependent, it is also called the theta state. If the 2 nd virial coefficient is exactly zero, then we refer to the solvent as a theta solvent. Contrarily, if the term is negative, polymer-polymer interaction is preferred, and therefore the coil contracts. If A 2 is positive, it means that the polymer-solvent interaction is favorable and therefore the polymer coil will expand. salt concentration) as well as the pH value and the temperature of the dispersion.įor polymer solutions, based on the sign of the 2 nd virial coefficient, we differentiate between good, bad and theta solvents. The core and shell are two different material. A 2 is dependent on the ionic strength (e.g. Core-shell nanostructure as the name suggests consists of a core encapsulated by a shell. By rationally tuning the cores as well as the shells of such materials, a range of coreshell. While a negative value suggests that aggregation is likely, a positive value reflects good particle-solvent interactions, and therefore stability. Coreshell nanoparticles (CSNs) are a class of nanostructured materials that have recently received increased attention owing to their interesting properties and broad range of applications in catalysis, biology, materials chemistry and sensors. In the case of protein or nanoparticle dispersions, the 2 nd virial coefficient can be used to predict aggregation in different solutes. However, the exact interpretation of the thermodynamic term differs for different sample groups. In general, if the second virial coefficient is positive, particle-solvent interactions are energetically favorable, while if the term is negative, particle-particle interactions are favored. This parameter is a thermodynamic term, which describes the particle-solvent and particle-particle interactions. īesides the molecular mass, the method of static light scattering also determines the second virial coefficient (A 2). If the radius of gyration is of interest, an X-ray source is required (see also small-angle X-ray scattering, SAXS). As the scattering intensity is uniform around the particles, the radius of gyration cannot be determined using laser-based instruments. An independent measure of the Li concentration in the core was obtained from HAADF STEM imaging of precipitate cores after the high-temperature step, but before the growth of the Li-rich shell in. This approach is inherent to the static light-scattering method, which is explained in detail below. In this case, the evaluation is performed through the Debye plot which marks Kc/ΔR over the concentration (s. The connection between scattering intensity and molecular mass is described in the Debye-Zimm equation, which is the theoretical basis for static light-scattering measurements: As the intensity of scattered light is proportional to the radius of the particle, this information can be used to draw a conclusion about the size of the particles in the dispersion. When light comes in contact with any particle, it is forced to deviate from a straight trajectory.
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