Fabrication And Wettability Researchof PDFMA Based Polymer Materials

Superhydrophobic fluorinated materials with excellent chemical and physical properties have attracted much attention because of their great application value in the fields of biotechnique, daily life, and national defense. Researches on superhydrophobic fluorinated materials indicate that the outstanding surface properties depend on the surface enrichment and structure of fluorinated moieties. Therefore, it is challenging in fabricating superhydrophobic fluorinated materials with the surface hydrophobic modification effects of fluoromonomers developed to the most extent by designing the structure of fluoropolymers.A series of poly(methyl methacrylate)(PMMA-Br) homopolymers and poly(methyl methacrylate)-b-poly(dodecafluoroheptyl methacrylate)(PMMA-b-PDFMA) diblock copolymers with different chain lengths were synthesized via atom transfer polymerization (ATRP), and superhydrophobic homopolymer or copolymer films were achieved by electrospraying. Due to the high chain mobility, electrosprayed PMMA50.6-Br film with continuous branches-like morphology was obtained at the flow rate of5uL/min with a large water contact angle of156o and a low hysterisis angle of3o, and the film formed at the flow rate of2mL/h is relatively flat with a low water contact angle of84o. PMMA-b-PDFMA having long PMMA blocks and short PDFMA blocks shows similar hydrophobicity to the corresponding PMMA-Br because of the formation of polymer micelles consisting of a core of PDFMA and a shell of PMMA during the film formation. The surface hydrophobicity could be greatly enhanced by increasing the weight fraction of fluorine in the diblock copolymer, and superhydrophobic film having a water contact angle of160o can be achieved by electrospraying PMMA147.9-b-PDFMA17.5with the fluorine content of18.3%at any selected flow rate. X-ray photoelectron spectroscopy (XPS) detections indicate that, THF favors the surface segregation of hydrophobic groups by comparing with DMF, and films prepared with THF as solvent are more hydrophobic.By the combination of ATRP and solution radical polymerization, amphiphilic graft copolymer of poly (methyl methacrylate)-r-poly(hydroxypropyl acrylate)-g-poly (dodecafluoroheptyl methacrylate)(PMMA-r-PHPA-g-PDFMA) was synthesized, and superhydrophobic fibrous films were obtained by electrospinning technique. Effects of polymer concentrations, flow rates, and solvents on the fibrous surface morphologies and properties were investigated in detail. Results indicate that the polymer concentration has great effects on the fibrous morphology and no obvious effects on the fibrous hydrophobicity, and the mean fibrous diameter shows a dependence on polymer concentration. The mean fibrous diameter increases by increasing the THF proportion in the solvent, and the superhydrophobic film with a water contact angle of165o and a hysterisis angle of2o can be achieved. The surface segregation of PDFMA would result in the high fluorine content at the fiber surface, and the fluorine content at the fiber surface prepared from the mixed solvent of dimethylformamide (DMF) and tetrahydrofuran (THF) with the mass ratio of1:1is29.1%; however, the fluorine content is up to34.8%with THF as solvent because THF favors the surface enrichment of fluorine. The uniform APTES-PMMA can be obtained by introducing THF into the solvent system.(3-Aminopropyl) triethoxysilane (APTES)-terminated PMMA, polystyrene (PS), and PDFMA were obtained via ATRP technique with bromine-terminated APTES (APTES-Br) as initiator, and block copolymers of APTES-PMMA(PS)-b-PDFMA were prepared with the corresponding homopolymers as macroinitiators. Fibers with different morphologies and hydrophobicity were fabricated via electrospinning. As the good solvent for PDFMA block, trifluorotoluene (TFT) can decrease the adhesion between the APTES-PMMA-b-PDFMA fibers, and increase the mean diameter of APTES-PS-b-PDFMA fibers. Flow rates have no obvious effects on the fibrous morphologies in the selected range. Compared with the PMMA based APTES terminated polymer fibrous films, PS based polymer films have higher hydrophobicity with water contact angles larger than150o, and TFT can reduce the hysteresis angle of APTES-PS-b-PDFMA to4o, but can’t enhance the hydrophobicity of APTES-PMMA-b-PDFMA. Less fluorine content (7.8%) was detected at the APTES-PMMA-b-PDFMA surface, whereas more fluorine content (9.7%) was detected at the APTES-PS-b-PDFMA surface.Silica (SiO2) particles in the mean diameters of140,300, and550nm with narrow standard deviation in the range of4.4-5.8%were synthesized by the modified St ber method. The interparticle repulsions and particle-water interactions were enhanced by adding stearic acid (SA) as co-surfactant and methanol as co-solvent, and hexagonally close-packed (HCP) LB-SiO2particulate films were achieved. The self-assembled hydrophobic films of fluoropolymers with different structures were obtained by dipping LB-SiO2particulate films in the dilute polymer solutions, and the films of fluoropolymers synthesized via ATRP show a higher hydrophobicity, APTES-PDFMA/LB-SiO2has a WCA of153o. A large number of C-C and C-H groups at random fluoropolymer/LB-SiO2film leads to the low hydrophobicity. However, the23.8%of–CF3at the surface of APTES-PDFMA/LB-SiO2contributes to the high hydrophobicity.