Polyorganosiloxane nanoparticles as optical tracers

Latex diffusion at high volume fractions studied by fluorescence microscopy

“…6a. This value is in excellent agreement with other reports [11,12,28,[42][43][44]. When using φ m = 0.62 in the analysis, [η] = 2.7 was used [26].…”

Crosslinked Spherical Nanoparticles with Core-Shell Topology

“…For the silica system, the difference in reactivity and the low compatibility of dye monomers and TES leads to local clustering of labels during particle formation, which causes a change in the fluorescence emission spectrum with respect to the isolated dye molecules. [26] Organosilicon microgels labeled with the photoreactive dye orthonitrostilbene (ONS) have been successfully employed as tracers for diffusion measurements by FRS, [3,27] the particle mobility. We found that for tracers lacking the shell, i.e., pure ONS-labeled particles, in comparison to tracers with a non-functional shell of only 1 nm thickness, the mobility is decreased by more than a factor of 100.…”

“…Both tracer systems have successfully been used to investigate dynamical processes in colloidal dispersions, i.e., self-diffusion, convection, and even thermal diffusion, as has been described in detail elsewhere. [27,29,30] Here, it should be noted that for our gold-doped organosilicon microgels the non-functional shell is used to suppress any negative influence of the gold clusters on the tracer mobility (see above) as well as to control, via its mesh size, the gold cluster morphology by providing a kinetic barrier to diffusion of the gold ions into the reactive core. [28] …”

Tracer diffusion of polyorganosiloxane nanoparticles in solution: Effects of tracer topology and particle concentration

“…13,14 Technical details of the FRS setup used in our diffusion studies have been described previously. 16,17 Typical exposure time for creation of the holographic grating was 25-100 ms at laser power 100 mW.…”

“…It will be shown that the photoreactive label may have a strong influence on the observed particle mobility, and that these unwanted effects totally can be suppressed using a protective shell of 1 nm thickness or larger. Employing tracers with suitable protective shell for FRS experiments, and gold-labeled core-shell particles for dynamic light scattering ͑DLS͒ as published previously, 17 the single particle mobility of polyorganosiloxane microgels over a large concentration regime from dilute to 55 wt. % has been investigated.…”