Toner monolayer

Comparing PDMS/HMDS- and HMDS-modified silica particles, a lower phase shift of up to 70° has been observed for the PDMS/HMDS silicas, and for the HMDS silicas a higher phase shift of up to 90° has been found. Differences in phase shift values indicate the impact of surface modification on the local hardness of the silica particles. PDMS modification leads to a softer, polymer-like grafting, whereas pure HMDS modification oidy increases the hydrophobicity by a hard monolayer formation of trimethylsiloxy groups. HMDS-treated silicas seemed to show a weaker interaction with the toner resin surfaces. In contrast, PDMS/HMDS-treated silicas show stronger adhesion to the toner resin surfeces, so they can easily be imaged at high resolution. 

When the toner is loaded with pyrogenic silica particles, these appear as isolated protrusions at the surface (Fig. IB-D). Depending on the modification, the diameters of the protrusions range between 50 and 200 nm. When HMDS is used as the silylation reagent, a silane monolayer is fbrmed. In this case the diameter of the particles is ca. 100 nm. Such particles are adsmbed mainly as isolated aggregates to the toner surface (Fig. IB). PDMS-modified particles seem to coat almost the entire toner particle (Fig. 1C). Their topographical diameter is doubled conq)aied to that of the HMDS-coated particles. This can be explained by the formation of a polymer-like PDMS layer. HMDS/PDMS-coated silicas appear only as isolated protrusions with a diameter up to 250 nm (Fig. ID). 

A theoretical model to relate the Wiener spectrum to the toner deposit parameters is difficult to construct because the mathematical difficulties of dealing with projections of transforms of probability distributions quickly "hide" any simple relationships. Models have been constructed however for a crowded monolayer photographic emulsion (11), and for multilayers of emulsion (12). Although the analysis was done for one-dimensional geometry, extension to two dimensions was outlined. A different approach will be used here, which relies on the linearity property of the Fourier transform, and assumes that the location of the toner particles is independent of neighbors. 

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