Masson Jean-Loup, Green Peter F
Texas Materials Institute and Department of Chemical Engineering, The University of Texas at Austin, Austin, Texas 78712, USA.
Phys Rev E Stat Nonlin Soft Matter Phys. 2002 Mar;65(3 Pt 1):031806. doi: 10.1103/PhysRevE.65.031806. Epub 2002 Mar 7.
We determined the low-shear effective viscosity of entangled polystyrene thin film melts, in the thickness range of 27<h<100 nm, on SiO(x)/Si substrates. This was accomplished using a method based on the notion that thin liquid films can become unstable and rupture due to defects or to destabilizing, long-range van der Waals interactions (dewetting). The holes that are created in the film subsequently grow at a rate determined by a balance between the capillary driving forces and the viscous resistive forces. Based on the velocity of growth of holes on the substrate, we show that the viscosity decreases appreciably with decreasing thickness for 25<h<50 nm. These results are consistent with studies which suggest that the glass transition of entangled polystyrene thin film melts on SiO(x)/Si substrates exhibit an apparent decrease with decreasing film thickness over the same range of h.
我们测定了在SiO(x)/Si衬底上厚度范围为27<h<100nm的缠结聚苯乙烯薄膜熔体的低剪切有效粘度。这是通过一种基于以下概念的方法实现的：由于缺陷或不稳定的长程范德华相互作用（去湿），薄液膜可能变得不稳定并破裂。薄膜中形成的孔洞随后以由毛细驱动力和粘性阻力之间的平衡所决定的速率生长。基于衬底上孔洞的生长速度，我们表明，对于25<h<50nm，粘度随着厚度的减小而显著降低。这些结果与一些研究一致，这些研究表明，在相同的h范围内，SiO(x)/Si衬底上缠结聚苯乙烯薄膜熔体的玻璃化转变随着薄膜厚度的减小而明显降低。
