Study On The Farbication And Properties Of Bionic Porous Honeycomb Films

Bionic design principle of learning from nature provides excellent methods and means to create new structural and functional materials. In recent years, ordered honeycomb porous films have received extensive attention owing to its important scientific value and application prospect in many fields such as optoelectronic devices, efficient catalysis, life science,micro-nano filtering, etc. Yet the research about the fabrication of porous membrane with transparent structure and the diversified application of porous membrane is still inadequate. Based on the above background, we fabricated a series of organic or organic/inorganic composite porous membrane under different conditions on the basis of "Breath-figure" method in this dissertation. We have not only realized the preparation of porous membrane with transparent structure on AAO substrate, and also applied the honeycomb porous membrane to the study of bionic ion channels and superwetting materials.The whole contents are listed as follows:1. Preparation of the honeycomb porous polyimide(PI) film and the influence of experimental conditions on its morphology. In this thesis,we fabricated a series of porous membrane with different morphology by PI chloroform solution with five kinds of concentration under five kinds of airflow rates through "Breath-figure" method.SEM analysis showed that the pore size of the porous film decreases with the increasing of polymer concentration and air flow rate and has a whole distribution of 0.21 μm to1.41 μm. Well-shaped porous membrane with regular pores can be obtained under the condition of using polymer solution with concentration of 1% to 1.5% and under air flow rate of 1 L/min to 2 L/min,while porous film with random pore size distribution and even none holes can be formated when the concentration and air flow rate is too large; We fabricated film on the anodic aluminum oxide(AAO) substrate with different invasive and roughness under optimum conditions of 1% polymer concentration and air flow rate of 2 L/min. We found that the pore size of the film increased with the enhancement of hydrophobicity and roughness of the basement and meanwhile we successfully fabricated porous membrane with transparent structure was on the hydrophilic AAO substrate with 200-300 nm aperture. This open pore structure porous film possess directional water-penetration characteristic.2. Preparation of the composite PI/AAO honeycomb porous film and research about its ion transport properties. In this part,we fabricated composite PI/AAO porous film on the base of AAO with five kinds of aperture through "Breath-figure" method and we realized its innovative application in the study of bionic ion channels. Results show that channels prepared on AAO substrate with three kinds of aperture of 27 nm, 60 nm and 95 nm possess ion transport rectification characteristics responding to acid and alkali. The rectifying value increases with the decreasing of AAO pore sizes and increasement of electrolyte concentration and reach the highest in alkaline conditon. While the composite film fabricated on AAO with large aperture and the single AAO channels have no rectification.Analysis combined with SEM showed that the rectification arise from the synthetic action of asymmetric structure,surface charge and wettability of the composite film channels,and the difference of wettability led to the unity of the rectification direction under acid and alkali environment.3. Preparation of the honeycomb porous iron oxide coating and research about its superwetting properties. We fabricated three kinds of poly(styrene- b- ethylene oxide)/ferric chloride composite film with different proportion via "Breath-figure" method combined with spin-coating and obtain honeycomb porous coating material after calcining. XPS and XRD analysis show that the coating is composed by ?-Fe2O3. Wettability characterization indicated that only sample 2 display superwetting and low adhesion to oil(water) and bubbles in water(oil) media. SEM analysis showed that sample1 have micro porous structure while sample 2 and sample 3 have micro/nano composite structure, but the morphology of sample 3 is relatively disordered. Based on the above results, we considered that the microtopography difference of the three kinds of samples lead to different wettability models of droplets and bubbles on their surfaces under multiphase media,thus show different wettability characteristics.