Synthesis And Properties Of Novel Aromatic Polyamides Containing Bulky Xanthene And Trifluoromethyl Pendants

In this dissertation, the recent progress on the study of polyamides Containing bulky xanthene groups and Trifluoromethyl Pendant groups were investigated. This paper was mainly composed of five parts as follow. 1. Synthesis and property of Bis(4-hydroxyphenyl)xanthene(BHPX) Summary and improvement of synthesis Bis(4-hydroxyphenyl)xanthene(BHPX). BHPX was prepared by reaction of xanthone with thionyl chloride, affording intermediate 9,9-dichloroxanthene, followed by treatment with phenol in refluxing xylene in a one-pot, two-step synthetic procedure.The xylene and excess phenol were distilled in vacuo at destined temperatures respectively. And then the crude product was recrystallized more than twice..While the yield was only 75%. To deal with this problem, I soaked the crude product with toluene in refluxing before recrystallization. By this means, the crude product was recrystallized only once and the yield reached more than 85%2. New fluorinated polyamides were prepared directly from a new diamine,9, 9-bis[4-(2-trifluoromethyl-4-aminophenoxy)phenyl]xanthene (BTFAPX) with various aromatic dicarboxylic acid chlorides by low-temperature polycondensation. The polymers were produced with moderate to high inherent viscosities of 0.65-1.01 dL/g, respectively. Nearly all the polymers were readily soluble in amide-type polar aprotic solvents (e.g., N, N-dimethylacetamide (DMAc) and N-methyl-2-pyrrolidinone), and even in less polar solvents such as dimethyl sulfoxide and pyridine, and afforded transparent, light-colored, and flexible films upon casting from DMAc solvent. The polymers showed glass transition temperatures between 235-284℃and 10% weight loss temperatures ranging from 495℃to 532℃and 476℃to 510℃in nitrogen and air, respectively, and char yields higher than 55% at 800℃in nitrogen. All polymers were amorphous and their films exhibited tensile strengths of 64-95 MPa, elongations at break of 6-9%, and tensile modulus of 1.9-2.5 GPa. These polymers had low dielectric constants ranging from 3.65 to 4.03 (100 Hz), low moisture absorption in the range of 0.56-1.14%, and high transparency with an ultraviolet-visible absorption cut-off wavelength in the 334-372nm range.3. A series of fluorinated polyamides were prepared directly by low-temperature polycondensation of a new cardo diacid chloride,9, 9-bis(4-chloroformylphenoxyphenyl)xanthene (BCPX), with various diamines containing trifluoromethyl substituents in N, N-dimethylacetamide (DMAc). Almost all polymamides showed excellent solubility in amide-type solvents such as DMAc and can also be dissolved in pyridine, m-cresol and tetrahydrofuran. These polymers had inherent viscosities between 0.77 and 1.31 dL/g, respectively. The resulting polymers showed glass transition temperatures (Tg) between 240-258℃and 10% weight loss temperatures ranging from 484℃to 517℃and 410℃to 456℃in nitrogen and air, respectively, and char yields at 800℃in nitrogen higher than 55%. All polymers were amorphous and could be cast into transparent, light-colored, and flexible films with tensile strengths of 81-100 MPa, elongations at break of 8-12%, and tensile modulus of 1.6-2.1 GPa. These polymers had low dielectric constants of 3.34-3.65 (100 KHz), low moisture absorption in the range of 0.76-1.91%, and high transparency with an ultraviolet-visible absorption cut-off wavelength in the 325-345nm range.4. A series of novel fluorinated copolymides containing xanthene structures were synthesized from 9,9-bis[4-(2-trifluoromethyl-4-aminophenoxy)phenyl]xanthene (BTFAPX), p-phenylenediamine(PDA) and isophthaloyl dichloride(IPC) by low temperature solution polycondensation under N2 atmosphere, respectively. These copolymers were characterized by FT-IR, DSC, TG, etc. The copolymers were produced with moderate to inherent viscosities of 0.41-0.73 dL/g, respectively and nearly all of them were readily soluble in polar aprotic solvents (e.g., N, N-dimethylacetamide (DMAc) and N-methyl-2-pyrrolidinone (NMP)) at room temperature. Tg's of the copolyamides were between 266℃and 278℃. The results showed that these new copolymers exhibited excellent heat-resistance,the onset temperatures taken at 10% weight loss of the in nitrogen and air were in the range of 429-501℃and 418-476℃, respectively, and char yields higher than 55% at 800℃in nitrogen. These polymers had low moisture absorption in the range of 1.50-3.01%,5. A series of novel fluorinated copolymides containing xanthene structures with high molecular weight were synthesized from 1,4-bis(2-trifluoromethyl-4-aminophenoxy)benzene(BFTAB), p-phenylenediamine and 9,9-bis(4-chloroformylphenoxyphenyl)xanthene (BCPX) by low temperature solution polycondensation under N2 atmosphere, respectively. These copolymers were characterized by FT-IR, DSC, TG, etc., The copolymers were produced with viscosities of 0.82-1.31 dL/g, respectively and all copolymers were readily soluble in common polar aprotic solvents (e.g., N, N-dimethylacetamide(DMAc), dimethylformamide(DMF), dimethyl sulfoxide(DMSO), tetrahydrofuran(THF) and N-methyl-2-pyrrolidinone (NMP)) at room temperature. Tg's of the copolyamides were between 247℃and 288℃. The results showed that these new copolymers exhibited excellent heat-resistance,the onset temperatures taken at 10% weight loss of the in nitrogen and air were in the range of 525-486℃and 504-423℃, respectively, and char yields higher than 53% at 800℃in nitrogen. These polymers had low moisture absorption in the range of 0.96-1.72%,...