论文部分内容阅读
This thesis explores the pore formation mechanisms of the breath figure method via spray coating.The breath figure method is indisputably one of the cutting edge practices for producing well characterized porous materials nowadays because of its versatility,robustness,and especially as it involves simple steps and unambiguous tools.The major setback however is the complexities involved in the pore formation mechanism.Regardless,in-depth studies of the process mechanism usually reveal additional prospects,which in turn boost the relevance of the process till date.Spray coating on the other hand is a viable scalable deposition technique commonly useful for coating large area surfaces and for devices fabrications.Herein,an erudite study of the influencing parameters on the pore formation mechanism of breath figure method via spray coating technique is presented.Several screening experiments were conducted to probe a wide range of parameter values as it influences the optimization process for fabricating highly ordered and regular porous films and structures.Parameters such as temperature,relative humidity,gas flow rate,nozzle to substrate distance,and different solvent choices including water-in-oil emulsions are holistically tuned.The surface morphology of the synthesized thin film was investigated using scanning electron microscopy and optical microscopy.Chloroform-PS solution was utilized as the casting film.The spray solvents explored are Chloroform,Tetrahydrofuran（THF）and Chloroform-Methanol mixture.Three volume ratios of water-in-oil emulsion was prepared viz;0.6% vol,1.8% vol and 3.6%vol.It was found that the substrate geometry and the ratio of water to oil in the emulsion largely influenced the pore formation pattern.Overall,in this work,a “standard parameter”was established after exploring series of experimental conditioning.This so called “standard parameter” could serve as insights for future studies specifically as it involves combining breath figure mechanism with spray coating techniques.In our exploration,it is revealed that the spray coating technique makes the fabrication of breath figured films easier to practice as it depends less on and less on external conditions,showing potentials for multifunctional surface patterning applications.Although no standard process or mechanism for the breath figure method is yet known specifically as it involves spray coating technique,however the established procedure in this thesis is able to set a fundamental knowledge for future works.