Research On The Direct Pore-forming Breath Figure Technique

What we reported here is a facial self-assembly method based on Breath Figure(BF)Method,called modified Breath Figure(mBF)Method.Different from the traditional way,in mBF,solute is departed from casting solution.Firstly,the flat polymer surface is fabricated by casting polymer solution under a dry environment or by the tablet machine straightforward.Secondly,immersing the polymer into the solvent to swell and transferring it to a high humidity environment,with the effect of capillary force and Marangonoi convection,the water droplets condense onto the surface of the solvent,which leaves the porous structure onto the surface of the polymer ultimately.For researching the methodology of mBF,we fabricated the porous structure,successfully,onto the surface of polymers,like PS,ABS,PLA,PCL and PMMA,with the modification of the solvent including chloroform,dichloromethane,tetrahydrofuran and the corresponding DDA solutions.It is found that the pore size of the structure increases with decreasing the saturated vapor pressure of the solvent and adding DDA helps to stabilize the interface between water and solvent,as well as increasing the pore size.All these above indicates the universality of mBF.In the next work,we try to make breakthrough in the limitation of merely fabricating pores onto the 2D substrate of traditional BF.By purchasing or fabricating ourselves,the 3D structures such as polymer tubes,bars,quadrangulars and spheres were obtained.By immersing the 3D structured polymers into the pure or mixed solvents and transferring them to a high humidity environment,the porous structures were obtained.It is the first time that porous structure is fabricated onto the surface of 3D substrate based on BF,which improves the application value of mBF tremendously.Last but not least,a scalable self-assembly route for fabricating a hierarchically structured material is reported here,possessing the property of superhydrophobicity,based on mBF.The composite-structured elastmers with dynamicllay controllable micro-and nano-scale roughness were fabricated by stamping closed-packed monolayer of monodispersed silica particles,with different sizes,onto the surface of PDMS protrusion arrays,prepared by copying various molding mBF films.The result of water contact angles(WCAs)measurement revealed that the variations in size features of either micro-scale or nano-scale make little difference in the WCAs of micro-patterned or composite-structured elastomers.We have found out that the ratio of prominence pitch to protrusion diameter of structured PDMS samples keeps to be constant when the micro-or nanoscale roughness varied a lot.The computation based on Cassie's law indicates that such geometrical feature contributes to the constant WCAs upon the varied roughness both in micro-and nano-scale.