Cient of PAI material. This was because the volume of trifluoromethyl within the side chain was fairly large, and also the steric impact was obvious when the content was relatively high, which would have an effect on the regularity and flexibility with the PAI molecular chain and raise the friction PF-06873600 web coefficient [17,18]. This was consistent together with the study report that the friction coefficient progressively elevated using the decrease of flexibility [19,20]. The wear of PAI(O), PAI-1, PAI-2, PAI-3, PAI-4, PAI-5, and PAI(F) gradually elevated. This was because the volume of trifluoromethyl was somewhat massive. With all the raise of trifluoromethyl content material, the intermolecular force of PAI decreased, plus the bulk density of PAI also decreased. When the material was subjected to friction shear, the material loss effortlessly occurred on the surface. three.four.two. Scanning Electron Microscope Analysis The friction surfaces of PAI material were scanned by electron microscope, as shown in Figure six. The put on mechanism of PAI copolymer synthesized by four,four -diaminodiphenyl ether was abrasive wear and slight adhesive wear. Together with the boost on the level of 2,two bis (trifluoromethyl)-4,4 –Ethyl Vanillate Anti-infection diaminophenyl ether, the adhesive wear degree of PAI terpolymer elevated. When the molar ratio of four,4 -diaminodiphenyl ether to 2,2 -bis (trifluoromethyl)4,four -diaminophenyl ether was 5:five, the adhesive wear degree of PAI terpolymer was the highest. When the molar ratio of 4,four -diaminodiphenyl ether to two,2 -bis (trifluoromethyl)four,four -diaminophenyl ether was 9:1, the wear mechanism of PAI terpolymer was abrasive put on. The put on mechanism of PAI copolymer synthesized by two,two -bis (trifluoromethyl)4,4 -diaminophenyl ether was primarily abrasive wear. The results showed that the put on mechanism of PAI material changed with the diverse amount of diamine monomer.Figure 6. Cont.Components 2021, 14,ten ofFigure six. SEM diagram of friction surface of synthetic PAI supplies.three.five. Hydrophobic Performance Test The water make contact with anglediagrams of PAI are shown in Figure 7, and the specific values are shown in Table 6. The water get in touch with angle of PAI synthesized by 4,four -diaminodiphenyl ether was 77.7 . With the increase from the amount of2,2 -bis (trifluoromethyl)-4,four diaminophenylether monomer, the water contact angle of PAI material steadily enhanced. The water get in touch with angle of PAI synthesized by 2,2 -bis (trifluoromethyl)-4,four -diaminophenyl ether was the highest, reaching 92.three . The bigger the water speak to angle, the stronger the hydrophobicity of your material surface. The outcomes showed that the hydrophobic capability of PAI improved with the boost of trifluoromethyl content, which was resulting from the hydrophobicity of fluorine atoms plus the hydrophobicity of PAI enhanced by fluorinecontaining groups [7,8]. The water absorption of PAI(O), PAI-1, PAI-2, PAI-3, PAI-4, PAI-5, and PAI(F) decreased together with the enhance of trifluoromethyl content. The study outcomes of water absorption also showed that trifluoromethyl could reduce the water absorption of components [7,8].Table six. Water contact angle and water absorption price of synthetic PAI components. Sample Number Water contact Water absorption/ angle/ PAI(O) 77.7 two.79 PAI-1 85.four two.18 PAI-2 89.2 two.01 PAI-3 90.4 2.00 PAI-4 91.five 1.86 PAI-5 92.0 1.72 PAI(F) 92.3 1.Components 2021, 14,11 ofFigure 7. Water make contact with angle diagram of synthetic PAI supplies.4. Conclusions Within this paper, four,4′-diaminodiphenyl ether and two,2′-bis (trifluoromethyl)-4,4’diaminophenyl ether were selected fo.