| Summary: | 碩士 === 大同大學 === 化學工程研究所 === 91 === First, A diamime monomer with ether-ketone group, 4,4’-Bis(4-aminophenoxy)benzophenone (2) was prepared through the nucleophilic substitution reaction of 1-chloro-4-nitrobenzene with 4,4’-Dihydroxybenzophenone in the presence of potassium carbonate in N,N-dimethylformamide, followed by catalytic reduction with hydrazine and Pd/C. Polyimides 5a-f(H), 5a-f(C) and copolyimides 5b-d/m(e-f) were synthesized from 2 and six kinds of commercial aromatic dianhydrides (3a-f) via thermal or chemical imidization method. Poly(amic acid) (PAA, 4a-f) had inherent viscosities range from 0.81 to 0.98 dL/g. PI of thermal imidization method was showed poor solubility even sulfuric acid. But PI of chemical imidization method 5e,f(C) and co-PI(C) could be dissolved. The reason is that the ketone group of PAA segments linked with the terminal amino group of polymer chains during thermal imidization. PI films 5a-f(H) had tensile strengths of 101-118 MPa, elongations to break of 11-32%, and initial moduli of 2.1-2.8 Gpa. The glass transition temperatures of 5 series were in the range of 252-278 ℃, and the temperatures of 10% weight loss (T10) were above 529 ℃, and their residues more than 50% at 800 ℃ in nitrogen. The 5 series also measured the color, dielectric constants and moisture absorptions. Their films had cutoff wavelengths between 378-421 nm, b* values ranging from 16.4 to 77.1, dielectric constants of 3.47-3.85 (1 MHz), and moisture absorptions in the range of 0.31-0.46 wt %.
Second, A novel fluorinated diamine monomer, 1,4-bis[4-amino-2-trifluoromethylphenoxy]-2,5-di-tert-butylbenzene (2’), was prepared through the nucleophilic substitution reaction of 2-chloro-5-nitrobenzotrifluoride with 2,5-di-tert-butylhydroquinone in the presence of potassium carbonate, followed by catalytic reduction with hydrazine and Pd/C. PI 5’a-f were synthesized from diamine 2’ and various aromatic dianhydrides 3’a-f via thermal or chemical imidization method. These polymers had inherent viscosities in the range from 0.77 to 1.01 dL/g. PI were dissolved in N-methyl-2-pyrrolidone (NMP), N,N-dimethylacetamide (DMAc) and N,N-dimethylformamide (DMF); they were even soluble in Dioxane, tetrahydrofuran (THF) and dichloromethane (CH2Cl2). Polyimide films had tensile strengths of 93-114 MPa, elongations to break of 9-12%, and initial moduli of 1.7-2.1 GPa. The glass transition temperatures were in the range of 255-288 ℃. The 10% weight loss temperatures(T10) was between 472-523 ℃ in the nitrogen and T10 was above 460 ℃ in the air. Compared with polyimides 6’ series based on 1,4-bis[4-aminophenoxy]-2,5-di-tert-butylbenzene, polyimides 5’ series showed better solubility and lower color intensity, dielectric constant, and moisture absorption. 5’(C) show cutoff wavelengths between 363-404 nm, b* values ranging from 6.5 to 40.2 and 5’ series reveal dielectric constants of 2.73-3.30 (1 MHz), and moisture absorptions in the range of 0.12- 0.29 wt%.
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