Effect of surface temperature on adhesion of nanoparticle-coated microparticles

Abstract Toner microparticles are coated with silica nanoparticles for modulating their adhesiveness to optimize two competing requirements in the electrophotographic process: low adhesion for facilitating particle transport and high adhesion with deposited substrates prior to high temperature fusing. In addition to the adhesion effect of nanoparticle coating, nanoparticle-coated toner microparticles are subjected to various thermal fields during utilization. Understanding the effect of temperature on particle adhesion properties has the potential to improve energy efficiency, process predictability and print resolution. In current work, the effect of surface temperature on the adhesion bond between single nanoparticle-coated toner microparticles and a silicon substrate is investigated in a non-contact/non-invasive manner by monitoring the rocking dynamics of acoustically excited single microparticles on a silicon wafer surface. In the reported spectral experiments, at a range of substrate temperature levels from 15 to 30 °C, the work-of-adhesion values of the surface-particle bond are evaluated from the acquired rocking resonance frequencies of the single toner microparticles. Rayleigh Surface Acoustic Waves (SAW) are employed to generate highly controllable surface motion to excite the vibrational modes of deposited microparticles, through which the out-of-plane transient responses of their apexes are acquired using a laser vibrometer. In addition to surface temperature, the effect of coating nanoparticle spatial distribution on the adhesion properties of the microparticle is observed and explained by proposing possible contact configurations, depending upon how silica nanoparticles are accumulated in and around the particle-surface contact zone. Finally, it is observed and reported that the relative humidity (RH) can play a significant role in microparticles rocking motion dynamics and adhesion.