Application Of Non-Traditional Breath Figure Method In Three-Dimensional Pore-Forming And Fabrication Of Stimuli-Responsive Surfaces

Breath figure(BF)method is a cost-efficient and flexible surface patterning technique.Two kinds of non-traditional BF methods,namely solvent-treatment BF method(st-BF)and inverse emulsion-based BF(In-BF)method are established for 3D pore-formation and fabrication of stimuli-responsive patterned surfaces,respectively.Facile pore formation on the surface of pre-shaped polymeric objects with different 3D structures [polystyrene(PS)sheets,polystyrene microspheres,polylactic acid(PLA)fibers] were achieved by using st-BF method.Different from the traditional BF method in which the polymer solution is cast into a film,for st-BF,solute is no longer needed in the cast solution.Specifically,the surface of pre-shaped 3D polymeric objects was directly treated with the solvent in different ways,and transferred to a chamber with humid environment.Polymers in the upper surface was then solvated into solved or swelled state.With the evaporation of the solvent,the water droplets condense onto the surface for nucleation,growth,alignment,and after drying,a patterned structure with porous array is emerged in-situ on the surfaces.Three different procedures for adopted to apply the solvent onto differently shaped polymers.The PS sheets with macroscale structure were treated by using solvent dip-coating method,and the effects of different dipping speed and dipping time on the porous structure were explored;Pore formation on the surface of PS spheres with microscale structure by using solvent drop-coating method,and the conditions for the pore-forming were explored by adjusting the solvents,adding amount of the solvent and humidity environment;Pore formation on the surface of sheets,microspheres and fiber were achieved by solvents vapor treatment,and the influence of the pore-forming conditions including different solvents vapor and the temperature difference between substrate and vapor were explored..In addition to the successful achievement of pore-forming on the surface of polymeric products,we further explored the characteristics of the two methodological functions of functional composition modification and regional patterned surface by the st-BF method.We combined the Pickering emulsification effect with the process of the st-BF method to introduce solid particles as the second component outside the pore-forming material and confirmed that the solid particles can obtain a selectively modified assembly morphology on the surface of pre-shaped 3D polymeric objects(PS sheets,PS microspheres).We further explored the assembly behavior of particles with different hydrophilic/hydrophobic properties on the surface,as well as the assembly effect in the process of pore formation on different curvature surfaces.In addition,we have successfully achieved the preparation of the regional patterned structure on the surface of the PS sheets by using the st-BF method as the solvent erasable effect of the solvent treatment process.P(NIPAM-AA-FCA)microgel with dual stimuli-responsive was introduced into the BF process to prepare patterned porous films using inverse emulsion system.The effects of emulsifier and water-oil ratio on the morphology of the porous structure prepared were investigated.Through the exploration of the pore-forming formula including the mass fraction of the microgel and the addition amount in the inverse emulsion,a stable emulsion system of high-efficiency loading of the microgel in the pores was obtained.Based on the dual stimuli-responsive properties of the functionalized microgel,FITC were loaded into microgel by diffusing that can be traced by fluorescence microscopy and molecular fluorescence.Through the dual stimulation of temperature and redox,re respectively,the corresponding the stimuli-responsive controlled release of FITC was successfully achieved,and the construction of the film-type patterned drug carrier was completed,which has potential applications in the field of biomedicine.