Preparation Of Fluoropolymer Coating With Microstructure On Substrate By The Breath Figure Method

Using the hydrophobic substance to prepare the microstructure coating on the surface of the substrate can significantly improve its surface hydrophobicity.A coating with microstructure has been widely used in the fields of template,filtration,biology,optoelectronics and biomimetic materials.Among these microstructure coating methods,the breath figure method has outstanding advantages due to simple operation,high production efficiency and low processing cost.This dissertation focuses on the construction of fluoropolymer coatings with roughened morphology by the breathing figure method,especially the construction of micro structured superhydrophobic coatings on the surface of fibers.The main contents are as follows:(1)Atomic transfer radical polymerization(ATRP)method was used to synthesize fluorinated polyacrylate(PAc)-polystyrene(PS)block copolymers.By changing the reaction time,block copolymers PTFOA-b-PS(2h)and PTFOA-b-PS(4h)with different PS segment lengths were obtained.The structure of the product was identified by FT-IR and 1H-NMR.The molecular weight and molecular weight distribution of the prepared copolymers were tested and analyzed by GPC,which confirmed the controllability of ATRP on the molecular weight of the polymers.(2)The coating was constructed by the static breath figure method using fluorine-containing block copolymers as raw materials and saturated vapor of different solvents as atmospheres.The effects of fluorinated block copolymer structure,solvent,concentration of polymer solution and substrate on the morphology and hydrophobicity of microstructured coatings were investigated.The micropore structure formed on the surface of the silicon wafer by the PTFOA-b-PS(4h)solution in carbon disulfide(CS2)under the water atmosphere had a concentrated pore size distribution and a uniform micropore structure on the surface.However,the hydrophobicity of the resulting microporous coating was not ideal.The XPS and EDS results showed that there were fewer fluorine-containing segments on the outer layer of the microporous coating.In contrast,by changing the atmosphere,for example under methanol/water(CH3OH/H2O)atmosphere,the microsphere coating was successfully constructed on a planar substrate by the static breath figure method.The effects of the ratio of methanol in the mixed atmosphere,solution concentration,PS segment content in the fluorinated block copolymer,substrate and solvent were investigated.Among them,the coating formed by 20 mg/mL solution of PTFOA-b-PS(2h)in Tetrahydrofuran(THF)under CH3OH/H2O atmospheres with methanol content of 60%and 80%produced the complex structures on the surface of microspheres.The water contact angles were 148.8 ± 1.8° and 150.3 ± 1.8°,respectively,the latter was superhydrophobic.XPS and EDS results showed that the fluorine element was enriched in the outerfield of the microsphere coating.The combination of the low surface energy of the fluorine element and the roughened complex structure of the microspheres can effectively improve the hydrophobicity of the coating.(3)The static breath figure method was applied to preprare microspheres or microporous coatings on the surface of fabrics/fibers by using reactive silanized fluoropolymers.Under methanol atmosphere,10 mg/mL solution of PTFOA-b-PS(2h)in THF was used to obtained prominent microsphere coating on the surface of the fiber,corresponding to the contact angle to water of 151.1 ±0.1°,which was superhydrophobic.Similarly,microporous structure coatings were formed on the fiber surfaces after being treated with PTFOA-b-PS(4h)under the moisture atmosphere.The 20 mg/mL PTFOA-b-PS(4h)solution in CS2 could form a relatively complete microporous coating on the surface of the fabric.Densely distributed micropore with large size appeared in the coating to give the contact angle to water of 147.2±1.6°,and the excellent hydrophobicity.By contrast,the fabric finished with Silanized-PTFOA-b-PS(2h)was coated by uniformly distributed and complete micropore on the surface of fibers.The study found that PTFOA-b-PS(2h)can develop the polymer microspheres on the surface of the fibers.It is worthy noting that when Silanized-PTFOA-b-PS(2h)was used,the microspheres showed the "micro-nano complex structure" and the as prepared fabric were more superhydrophobic.The contact angle to water of these two coating fabrics is 151.5±0.1° and 152.2 ± 2.3°,respectively.The element distribution on the surface of the treated fiber was studied,and the comprehensive properties such as thermal stability,washability,air permeability,and hardness of the finished fabric were tested.