RESUMO
Using fluorescence confocal microscopy we study the adsorption of single latex microparticles at a water-water interface between demixing aqueous solutions of polymers, generally known as a water-in-water emulsion. Similar microparticles at the interface between molecular liquids have exhibited an extremely slow relaxation preventing the observation of expected equilibrium states. This phenomenon has been attributed to "long-lived" metastable states caused by significant energy barriers ΔFâ¼Î³A_{d}â«k_{B}T induced by high interfacial tension (γâ¼10^{-2} N/m) and nanoscale surface defects with characteristic areas A_{d}≃10-30 nm^{2}. For the studied water-water interface with ultralow surface tension (γâ¼10^{-4} N/m) we are able to characterize the entire adsorption process and observe equilibrium states prescribed by a single equilibrium contact angle independent of the particle size. Notably, we observe crossovers from fast initial dynamics to slower kinetic regimes analytically predicted for large surface defects (A_{d}≃500 nm^{2}). Moreover, particle trajectories reveal a position-independent damping coefficient that is unexpected given the large viscosity contrast between phases. These observations are attributed to the remarkably diffuse nature of the water-water interface and the adsorption and entanglement of polymer chains in the semidilute solutions. This work offers some first insights on the adsorption dynamics or kinetics of microparticles at water-water interfaces in biocolloidal systems.
RESUMO
The Short-Wave Infrared Range (SWIR) from 900 to 1700 nm offers many unique opportunities for discovery in scientific imaging. However, the indium gallium arsenide (InGaAs) cameras capable of detecting this wavelength range typically suffer from excessive noise and image artifacts, making scientific imaging challenging. The NIRvana family of InGaAs cameras from Teledyne Princeton Instruments offer "SWIR for Science," through cutting-edge sensor cooling, thermal management, sensor shielding, and image corrections.