Tham khảo tài liệu 'polymer thin films part 8', kỹ thuật - công nghệ, cơ khí - chế tạo máy phục vụ nhu cầu học tập, nghiên cứu và làm việc hiệu quả | 164 Polymer Thin Films Wet a polymer surface As long as surface wetting is concerned at least one liquid and one solid surface are involved. Wetting a solid surface by a liquid is a surface phenomenon in which the liquid spreads on the surface and tends to cover it. Surface wetting has been thought to be a thermodynamic process which ends at equilibrium state of the system. According to their chemical activities wetting of solid surfaces can be classified into two categories nonreactive wetting in which a liquid spreads on a substrate with no chemical reaction or absorption and reactive wetting which is influenced by chemical reactions between spreading liquid and substrate material. Depending upon its basis - how the process is initiated and driven wetting can be classified into two types spontaneous spreading which is defined as the spreading of a liquid on a solid by itself without any external interference and driven spreading which is initiated and driven by some kind of external actions. Within the frame of this chapter the discussions are focused on non-reactive spontaneous wetting. Static contact angle For thermal dynamic system if the space is filled up with one continuum the assembly of all co-contact points at which two thermal dynamic phases join together forms a surface the assembly of all co-contact points at which three phases join together can form a line the cocontact points for four phases joining together cannot contact each other in the real space. Therefore topologically the spatial boundary that separates two thermal dynamic phases is a two dimensional surface when one more phase joins in the boundary that separates the three phases degenerates to one dimensional line and the boundary that separates four phases becomes isolated dimensionless points. There will be no real boundary that can connect more than four thermal dynamic phases in a real space. When a small amount of a liquid is put in contact with a flat polymer surface the .
