Effects of Hypergravity on Formation of Microporous Films by Dissipative Processes

Microporous polymer films can be prepared by casting a solution of hydrophobic polymer and amphiphilic polymer on a solid substrate using condensed water droplet arrays as templates. Bacause of the temperature nonuniformity of the solution surface owing to thermal convections, water condenses heterogeneously. The heterogeneous condensation of water droplets induces the formation of irregular-size and -arrangement microporous film. To evaluate the effect of gravity on microporous film formation, we have successfully prepared the test chamber for hypergravity experiments. From the hypergravity experiment, the thermal convection during solvent evaporation was forced to be enhanced under hypergravity. As a result, the microporous structure was not observed under hypergravity. These results provided insight on water-assisted microporous film formation. Furthermore, the results strongly suggested that the microgravity enviroment is suitable for uniform and well-organized microporous film formation.