Secondly pfotes sio 2 and original sio 2

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Secondly, PFOTES-SiO 2 and original SiO 2 nanoparticles with molar ratio 1:5, 2:4, 3:3, 6:0 were ultrasonically dispersed in 25 ml methanol separately. Thirdly, one quarter (approximately 30 ml) of the prepared sols were added to the nanoparticle suspensions prepared in step two respectively. The total amount of PFOTES-SiO 2 and SiO 2 nanoparticles was kept at 0.025 mol for each condition. After that, the obtained four solutions were placed in an ultrasonic bath for 15 min, and then magnetically stirred for another 4 hr. 2.4 Spray-coating of the sols The microscope glass slides were ultrasonically cleaned in ethanol for 10 min followed by rinse in deionized water for 5 min. Glass fibre reinforced epoxy (GFRE) substrates were first polished mechanically using 320 grit SiC sandpaper to remove surface contaminations, and then ultrasonically cleaned in ethanol for 10 min followed by rinsing in deionized water for 5 min. After that, the obtained four sols were spray coated onto the glass slides and GFRE substrates separately through an airbrush kit (AS06KB) with a 1.5 mm diameter nozzle using compressed air (pressure at 345 kPa). The distance between the airbrush and the substrate was kept at 10 cm. The airbrush was moved laterally back and forth until a uniform coating has been deposited. Finally, the prepared samples were cured in an oven at 110 C for 2 hr. The obtained coatings were labelled as TGS 1:5, TGS 2:4, TGS 3:3 and TGS 6:0 corresponding to the ratio of treated and untreated silica particles in the sol solution. 2.5 Characterization
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ACCEPTED MANUSCRIPT ACCEPTED MANUSCRIPT 6 The surface morphology of the coatings was examined by field emission scanning electron microscope (FESEM, JSM-6360, Japan). The wetting properties of the specimens were measured with a contact angle system (OCA 20, Dataphysics Co., Germany). The contact angle and rolling angle of DI water, glycerol, formamide, diiodomethane, diethanolamine, ethylene glycol, a-bromonaphthalene, castor oil, sunflower oil, hexadecane and dodecane were measured. The reported values were the average of five measurements obtained at different locations of the prepared coatings. The continuous rolling of liquids was recorded by the built-in CCD camera in the contact angle system. Confocal microscope was used for imaging surface roughness of the coatings. Pencil scratch test of coatings was assessed using a commercial pencil scratch tester (Scratch Hardness Tester Model 291, ERICHSEN) according to ASTM D3363 Standard Test Method. The bond strength between coatings and GFRE substrates was measured by cross-cut tape adhesion test based on ASTM D3359 Standard Test Method. After cross cutting, coatings were examined under optical microscope (Olympus BX51). The adhesion strength test was conducted by PosiTest Pull-Off adhesion test according to ISO 4624 Standard Test Method.
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  • Fall '19
  • Surface tension, nU, Surface energy

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