To understand the influences of nanoparticles on dewetting in ultra-thin films, both linear stability the- ory and numerical simulations are performed in the present study, with the consideration of oscillatory struct...To understand the influences of nanoparticles on dewetting in ultra-thin films, both linear stability the- ory and numerical simulations are performed in the present study, with the consideration of oscillatory structural （OS） forces. Long scale approximation is utilized to simplify the hydrodynamic and diffusion equations to a nonlinear system for film thickness and nanoparticle concentration. Results show that the presence of nanoparticles generally suppresses the dewetting process. Two physical mechanisms responsi- ble for this phenomenon are addressed in the present study. When the oscillatory structural forces are relatively smaller, the essential feature of film evolution is similar to the case of particle-free flow. The reduction of the linear growth rate and the postponement of film rupturing can be attributed to the increment of the viscosity due to the presence of nanoparti- cles. On the other hand, when the intensity of the OS forces becomes stronger, the stepwise thinning of film can be ob- served which prevents the film from rupture. Numerical sim- ulations indicate that this phenomenon is caused by the ex- istence of a stable zone due to the oscillatory nature of the structural forces. Another interesting finding is that the non- uniformity of the distribution of nanoparticle concentration might destabilize a spinodally stable film, and trigger the oc- currence of film dewetting.展开更多
基金supported by the National Natural Science Foundation of China (10872122)Doctoral Fund of Ministry of Education of China (20103108110004)+1 种基金Program for Changjiang Scholars and Innovative Research Team in University (IRT0844)Shanghai Program for Innovative Research Team in Universities
文摘To understand the influences of nanoparticles on dewetting in ultra-thin films, both linear stability the- ory and numerical simulations are performed in the present study, with the consideration of oscillatory structural （OS） forces. Long scale approximation is utilized to simplify the hydrodynamic and diffusion equations to a nonlinear system for film thickness and nanoparticle concentration. Results show that the presence of nanoparticles generally suppresses the dewetting process. Two physical mechanisms responsi- ble for this phenomenon are addressed in the present study. When the oscillatory structural forces are relatively smaller, the essential feature of film evolution is similar to the case of particle-free flow. The reduction of the linear growth rate and the postponement of film rupturing can be attributed to the increment of the viscosity due to the presence of nanoparti- cles. On the other hand, when the intensity of the OS forces becomes stronger, the stepwise thinning of film can be ob- served which prevents the film from rupture. Numerical sim- ulations indicate that this phenomenon is caused by the ex- istence of a stable zone due to the oscillatory nature of the structural forces. Another interesting finding is that the non- uniformity of the distribution of nanoparticle concentration might destabilize a spinodally stable film, and trigger the oc- currence of film dewetting.
