Phase separation has been well recognized as a usual mechanism for forming the porous microstructure of polymeric membranes. This study considers a binary liquid mixture of a polymer species and a solvent and investigates the system's behavior when it reaches the minimum interfacial energy between the phases with the formation of spinodal decomposition. The goal of this study is to employs the phase-field method to consider the wettability of the porous structure on the surface as well as its following contact angle with respect to the temperature gradient with distinct initial concentrations. Also, the effect of the temperature gradient, as well as concentration gradient on the volume fraction of the polymer-rich phases and porosity are investigated.