Synthesis and Characterization of Novel Aromatic Polyimides from Aromatic Diamine and 3,3''''',4,4'''''-p-Sexiphenyltetracarboxylic Dianhydride

Abstract

ABSTRACT:A new rigid tetracarboxylic dianhydride, 3,3"'", 4,4"'"-p-sexiphenyltetracarboxylic dianhydride, was synthesized in seven steps starting from diethyl 4-bromophthalate. New aromatic polyimides containing a p-sexiphenyl unit were synthesized from this tetracarboxylic dianhydride and various aromatic diamines by the conventional twostep procedure of ring-opening polyaddition in a polar amide-type solvent and subsequent thermal cyclic dehydration. These polyimides had inherent viscosities of 1.20-1.69 dL g-1 , and were insoluble in organic solvents. The polyimides were characterized by differential scanning calorimetry (DSC), thermogravimetry (TG), wide-angle X-Ray diffraction measurements, and dynamic mechanical analysis (DMA). Typical polyimides were noncrystalline and showed excellent thermal stability, and had glass transition temperatures (Tg) at about 250'C. Decrease in the modulus at the glass transition temperature was less than corresponding polyimides having no p-sexiphenyl unit due to the presence of the rigid p-sexiphenyl unit.

Synthesis and Characterization of Novel Aromatic Polyimides from Aromatic Diamine and 3,3””,4,4””-p-Quinquephenyltetracarboxylic Dianhydride

“…On the basis of T 10 , the polyimides had as high thermal stability as the polyimide from p-phenylene diamine and 3,3 ,4,4 -biphenyltetracarboxylic dianhydride, which was one of the most thermally stable polymer in the aromatic polyimides. 10 DSC curves of polyimides VIIIa, VIIIc, VIIId, and VIIIe showed glass transition temperature(T g ) around 230-265 • C followed by exothermic peaks (T c ) around 325-450 • C, above T g s. T g was essentially comparable to that of the previously reported polyimides prepared from 3,3 ,4,4 -p-quarterphenyltetracarboxylic dianhydride (m = 2) and 3,3 , 4,4 -p-sexiphenyltetracarboxylic dianhydride (m = 4), 6 at 235 • C and 233 • C, respectively, and did not undergo obvious transition due to crystallinity. This may be explained by the low rotational energy barrier around the ether linkages.…”

“…I was previously prepared by reactions involving the extension of phenylene unit using p-methoxyphenyl boronic acid. 6 Cross-coupling 8,9 of I with II, using Pd(PPh 3 ) 4 as catalyst, yielded tetraethyl 3,3 ,4,4 -p-quinquephenyltetracarboxylate III in 63%. Subsequent hydrolysis of III afforded quinquephenyltetracarboxylic acid IV in 92%, and IV was converted to tetracarboxylic dianhydride V by heating in diphenyl ether (84%).…”

“…Recently, we reported aromatic polyimides PI-Ar-m containing p-quarterphenyl (m = 2) 5 and p-sexiphenyl (m = 4) 6 unit, which were very rigid, and compared the properties of these polyimides with those of polyimides from 3,3 ,4,4 -p-terphenyltetracarboxylic dianhydride (m = 1) and 3,3 4,4 -biphenyltetracarboxylic dianhydride (m = 0), which have been previously prepared. 7 T g s were independent on the number of phenylene units (m) of the dianhydrides, while moduli were higher and decrement of moduli at the glass transition decreased with increasing m.…”

Synthesis and Characterization of Novel Aromatic Polyimides from Bis(4-amino-2-biphenyl)ether and Aromatic Tetracarboxylic Dianhydrides

“…3,3 000 ,4,4 000 -p-Quaterphenyltetracarboxylic(VIIg) dianhydride, 3,3 0000 ,4,4 0000 -pquinquephenyltetracarboxylic dianhydride(VIIh) and 3,3 00000 ,4,4 00000 -p-sexiphenyltetracarboxylic dianhydride (VIIi) were synthesized according to the method reported previously. [16][17][18] N-Methyl-2-pyrrolidone (NMP), N,N-dimethylacetamide (DMAc) and N,Ndimethylformamide (DMF) were purified by vacuum distillation over calcium hydride. Ethanol was purified by distillation.…”

Synthesis and Characterization of Polyimide from 4,4’-Diamino diphenyl ether having Substituents at 2,2’-position

“…The polyimide from 3 and pyromellitic dianhydride has been synthesized to investigate possibility of heat-resistant composite materials with good processability [9]. [12] were prepared as previously reported. 4-Fluoro-3-phenyl nitrobenzene was prepared as previously prepared [6].…”