T efficiency [1]. Polyamide-imide (PAI) can be a modified polyimide, which usually has repeated structural units (Scheme 1). It may be seen in the molecular structure that PAI includes two structural units, amide bond and imide ring, so PAI has some efficiency positive aspects more than PA and PI, for example high-temperature resistance, corrosion resistance, friction and put on resistance, excellent mechanical properties, and may be compounded with several substances, and so on. PAI is really a particular engineering plastic with excellent overall performance, which is often applied in very serious operating circumstances [5,6].Copyright: 2021 by the authors. Licensee MDPI, Basel, Switzerland. This short article is definitely an open access report distributed below the terms and situations of your Creative Commons Attribution (CC BY) license (https:// creativecommons.org/licenses/by/ four.0/).Materials 2021, 14, 6376. https://doi.org/10.3390/mahttps://www.mdpi.com/journal/materialsMaterials 2021, 14,2 ofScheme 1. PAI molecular structural formula.PAI polymer synthesized by 4,4′-diaminodiphenyl ether has far better complete properties, along with the raw material is inexpensive, which has much better engineering application prospects. 2,2′-bis (trifluoromethyl)-4,4′-diaminophenyl ether has precisely the same major chain structure as 4,4′-diaminodiphenyl ether, and also the side chain includes two trifluoromethyl groups, which has high fluorine content. Studies have shown that introducing fluorine or fluorine-containing groups into the molecular structure can lower the moisture absorption price of components [7], strengthen the heat resistance [8,10], improve the put on resistance [113], increase the solubility [14], and so on. There have been few reports onthe effects of fluorine atoms and fluorine-containing groups on PAI. Within this paper, two,2′-bis (trifluoromethyl)-4,4′-diaminophenyl ether and four,4’diaminodiphenyl ether have been compounded to synthesize PAI by the acyl chloride process [5,15]. The effects of trifluoromethyl on heat resistance, friction and put on resistance, hydrophobicity, and mechanical properties of PAI materials had been studied to prepare PAI supplies with excellent properties. two. Experimental two.1. Materials four,4′-diaminodiphenyl ether was analytically pure and bought from Aladdin (Shanghai, China). 2,2′-bis (trifluoromethyl)-4,4′-diaminophenyl ether was analytically pure and purchased from Changzhou Sunshine Pharmaceutical MCC950 MedChemExpress Technologies Co., Ltd. (Changzhou, China). 1,2,4-trimellitic anhydride acyl chloride(TMAc) was bought from Tokyo Chemical Market (Tokyo, Japan). Triethylamine as an acid-binding agent and catalyst was purchased from Aladdin (Shanghai, China). Acetic anhydride was analytically pure, employed as dehydrating agent, purchased from Aladdin (Shanghai, China). N-methylpyrrolidone(NMP) as aprotic polar solvent was bought from Aladdin (Shanghai, China). two.two. Preparation of PAI PAI synthesized by four,4′-diaminodiphenyl ether and TMAC was named PAI(O). When the molar ratio of four,4′-diaminodiphenyl ether to 2,2′-bis (trifluoromethyl)-4,4′-diaminophenyl ether is (9:1), (7:three), (five:five), (3:7) and (1:9), the synthesized PAI terpolymers were named PAI-1,PAI-2,PAI-3,PAI-4,PAI-5 in turn.PAI synthesized by two,2′-bis (trifluoromethyl)-4,4’diaminophenyl ether and TMAC was named PAI(F).The preparation process was as PF-06873600 medchemexpress follows: (1) Polymerization method Below the protection of nitrogen, NMP was added into a 500 mL four-necked flask, and also the quantity of NMP was eight times the total mass of trimellitic anhydride acyl chloride and diamine monomer.
