- Email: [email protected]
Preparation of phosphorus-containing polymers—XV. Preparation of phosphorus-containing polyamide-imides from N,N′-bis(4-carboxyphthalimido)-3,3′-diphenylalkylphosphine oxide and aromatic diacetamides
European Polymer Journal, Vol. 15, pp. 75 Io 79 © Pergamon Press Lid 1979 Printed in Great Britain
(X)14-3057 7901014)075502.00 0
PREPARATION OF PHOSPHORUS-CONTAINING POLYMERS--XV PREPARATION OF PHOSPHORUS-CONTAINING POLYAMIDE-IMIDES N,N'-BIS(4-CARBOXYPHTHALIMIDO)-3,3'-DIPHENYLALKYLPHOSPHINE AND AROMATIC DIACETAMIDES
FROM OXIDE
M. SATO and M. YOKOYAMA Department of Industrial Chemistry, Kogakuin University, 1-24-2, Nishishinjuku, Shinjuku-ku, Tokyo 160, Japan (Received 17 April 1978) Abstract--Phosphorus-containing polyamide-imides were prepared from N,N'-bis(4-carboxyphthalimido)-3,Y-diphenylalkylphosphine oxide and aromatic diacetamido derivatives by acidolysis; the reaction conditions are discussed. The resulting polymers were fairly soluble in DMA, DMF and conc. H2SO4; the reduced viscosities of polymers in DMA or cone. H2SO4 (0.2g/dl) at 30° were 0.19-0.32. The phosphorus-containing polymers have good thermal stability, and are self-extinguished immediately after the flame is removed. Most of the i.r. absorption bands of polymers vanished on heating at above 600°.
We have reported [3] the preparation of phosphorus-containing polyester-imide from N,N'-bis(4-carboxypht halimido)-3,3'-diphenylalkylphosphine oxide (BCIAP), having a preformed phthalimide ring, and various aromatic diacetoxy compounds by acidolysis; good thermal stability and flame resistance were shown. In the present work, as a continuation of studies on the preparation of phosphorus-containing polymers, polyamide-imides were synthesized from BCIAP and various aromatic diacetamido derivatives in vacuo; their properties were investigated and compared with those of analogous non-phosphorus polymers.
INTRODUCTION
Linear aromatic heterocyclic polymers, such as potyimide, polyester-imide and polybenzimidazole, have been reported by many authors. These polymers have good thermal stability but exhibit poor solubility in most organic solvents. Polymers containing phosphorus in the main chain are heat and flame resistant, and are soluble in polar aprotic solvents such as D M F and DMSO. Recently, phosphorus-containing polyimide[l] and polybenzimidazole[2] were prepared and their properties were disclosed.
0 II
0 tl
0
+ 0
0 0 II
0 .
--CH3COOH
.
.
0 II
.
0
R :
H 3CCOHN-R'--NHCOCH 3
o
CH3 ~ C4H9 ~
R' : (DAD)
(DADSI
(DADM) O
'
" ~
CH3~-/ (DAOPO) 75
(DADE)
76
M. SATO and M. YOKOYAMA RESULTS
EXPERIMENTAL
Diacetamides Aromatic diacetamido derivatives were obtained by the usual procedure for acetylation of aromatic diamines. Their melting points were as follows: 4,4'-diacetamidodiphenyl (DAD), m.p. 339-340 ~ (lit. [4] 340-343); 4,4'-diacetamidodiphenyl sulfone (DADS), m.p. 288~290 ° (lit. [5] 275-278"): 4,4'-diacetamidodiphenylmethane (DADM), rap. 233.5-235.0 '' (lit. [6] 233"): 4,4'-diacetamidodiphenyl ether (DADE), m.p. 231-232 ~' (lit. [7] 228-229"); 3,3'-diacetamidodiphenylmethylphosphine oxide (DADPO), m.p. 274-275.5" (lit. [8] 275-277").
Preparation of hisimide-carhoxylic acid monomers N,N'-bis ( 4- carhoxyphthalinfido ) - 3,3' - diphenylcyclohexylphosphine oxide (BCICP) To a solution of bis(3-aminophenyl)cyclohexylphosphine oxide (0.01 mole) in 15 ml of DMF. trimellitic anhydride (0.021 mole) was added and the reaction mixture was stirred for 20 hr at room temperature. It was poured into a large excess of water. The white precipitate was collected by filtration, repeatedly washed with water and dried in vacuum at room temperature. The product was dissolved in 20 ml of m-cresol and the solution was refluxed for 2 hr. It was then cooled and evaporated to dryness under reduced pressure. The resulting solid was recrystallized from acetone; yield 720,, m.p. 334 '~ (DTA method). Anal. Calcd. for C3~H27N2OgP: C, 65.26"~: H, 4.08°0: N, 4.23";,: P. 4.68"~;. Found: C, 64.34°~,; H, 4.42't,,: N. 4.09°%; P. 4.79~. N,N'-Bis(4-carhoxyphthalimido)-3,3'-diphenyhnethylphosphine oxide (BCIMP) and N,N'-bis(4-carboxyphthalimido)33'-diphenylbutylphosphine oxide (BCIBP) These substances were prepared by the method described above. Each product was heated in refluxing acetone. washed several times with acetone, and dried over phosphorus pentoxide in t~acuo. BCIMP: yield 62°,~,, m.p. 323" (DTA method). Anal. Calcd. for C3~H~gN2OgP: C. 62.63°~; H. 3.20°o; N, 4.71°0; P. 5.22°o. Found: C. 60.97°o; H, 3.41°%; N, 4.47°~,; P, 5.30°. BCIBP: yield 780,;. m.p. 328 ~"(DTA method). Anal. Calcd. for C34H25N2OgP: C, 64.17°o H. 3.93°0: N. 4.40°,,: P, 4.8700. Found: C. 64.02°,,; H. 4.29°,,; N. 4.70°o; P. 4.72°0.
AND
DISCUSSION
Preparation of monomer Previously [3], B C I M P and BCIBP were synthesized via bisamic acid from bis(3-aminophenyl)alkylphosphine oxide and trimellitic anhydride in 1:2 molar ratio. In the present paper, B C I A P was prepared by a modified method. The bisamic acid in m-cresol was refluxed for 6 hr and gave the corresponding bisimide-carboxylic acid in 62-78yo yield. Their structures were identified by elemental analyses and i.r. spectra. Experimental analyses agreed with calculated, i.r. Spectra showed the characteristic absorption bands of P--K) at l l 5 0 c m -1, P---C6H s at 1420cm -1, C6H5 at 1580 and 1480cm -1, C - - N at 1370cm -1 and imide ring at 1720 and 1780cm -1. It is considered that the shifts to lower frequencies of the absorption bands from the expected values (about 20 cm-1) are due to the increasing conjugation resulting from electronegative groups, such as P = O or C---O of carboxylic acid and imide ring, and aromatic ring. The absorption band corresponding to O H streching and a shoulder based on C = O of carboxyl group were observed at 2500 to 3000cm-1 and near 1700 c m - 1 respectively.
Phosphorus-containing polyamide-imide It has already been reported that polyamide-imides are synthesized from bisimide-carboxylic acid containing naphthalene ring and aromatic diacetamides by acidolysis without catalyst under reduced pressure and that they have good thermal stability; polymerization conditions were not reported in detail [9]. We now report the syntheses of phosphorus-containing polyamide-imides by acidolysis from bisimidecarboxylic acid and aromatic diacetamido derivatives. Polymerization conditions and physical properties are also discussed.
0.3
3,Y-[N,N'-bis( 4-carboxyphthalimido) ]benzophenone (B C IB) This substance was synthesized by the method described previously [3]: yield 7400. m.p. 331" (DTA method). Pol)'condensation A typical procedure for obtaining the polyamide-imide is described. BCIBP and DADS were mixed and charged into a four-necked flask. Heating for 2 hr at 320-325 ~ in vacuo (15-25 Torr) gave a dark-brown solid. When cooled, the resulting polymer was washed sequentially with stirring in DMF and then in hot acetone, and dried over phosphorus pentoxide at 150~ at reduced pressure. Characterization of polymers Infrared spectra were obtained on Jasco Model IR-S i.r. spectrometer. Thermal analyses were carried out with Shimadzu Model DT-30 thermal analyser in air and in nitrogen (30 ml/dl) and heating at a rate of 10°/min.
--~ 0.2 5 "El
/
0.1
i
0
i
i
i
1.0 1.5 2.0 Mota~" ratio (DADS/BC[BP) 0.5
Fig. 1. Effect of molar ratio on polycondensation of DADS and BCIBP. q,.a: Measured in DMA at 30% C = 0.2 g/dl.
77
Preparation of phosphorus-containing polymers--XV Table 1. Effect of reaction time and temperature on polycondensation of DADS and BCIBP* Time (hr)
Temp (°C)
Yield (%)
0.25 0.5 1.0 1.5 2.0 3.0 5.0 2.0 2.0 2.0
300-305 300-305 300-305 300-305 300-305 300-305 300-305 280--285 320-325 340-345
48 60 61 65 67 63 60 59 67 65
qr,,(t (dUg) 0.07 0.14 0.20 0.25 0.29 0.28 0.28 0.26 0.31
*Molar ratio: 1.0 (=DADS/BCIBP), Pressure: 15-25 Torr. "t Measured in DMA at 30 '~. C = 0.2 g/dl.
First, polymerization conditions were investigated under reduced pressure (15-25 Torr) by using BCIBP and D A D S in order to find the optimum conditions for the preparation of phosphorus-containing polyamide-imides. These results are presented in Fig. 1 and Table 1. Table 1 shows that the reduced viscosity is fairly constant for reaction times of over 2 hr and it increases with rise in reaction temperature. The polymers obtained at temperatures > 3 3 0 ° did not dissolve in D M F , conc. H2SO4 etc. From Fig. 1, viscosity is highest at the molar ratio of 1.0. This result suggests that the preparation of phosphorus-containing polyamide-imides should be carried out under following conditions: Molar ratio of 1.0; reaction time of 2 h r ; reaction temperature of 320-325 °. Under these conditions, melt polycondensations were run and the data are summarized in Table 2. Polyamideimides having a reduced viscosity in the range of
0.19-0.32 were obtained in a yield of 50--8Yk;,. Elemental analyses of various polyamide-imides agreed well with calculated values. The i.r. spectra of polymers showed that the absorption bands of carboxyt group disappeared and that of amido group appeared at 1660 and 1520cm-1. Non-phosphorus polymers showed the absorption band of C~--~-O at 1660cminstead of that based on P - - O at l l 5 0 c m - ~ . The formation of polyamide-imides were confirmed from these data. Most of the phosphorus-containing polymers dissolved in polar aprotic solvents such as D M F , DMA, and DMSO, and conc. H 2 S O 4, while non-phosphorus polymers were insoluble in organic solvents but soluble in conc. H2SO 4. Thus the phosphorus-containing polymers have better solubility in organic solvents than the non-phosphorus polymers. We have also prepared phosphorus-containing polyamide-imides from bisamide-anhydride and aromatic diamines by melt polycondensation[10]. These polymers were almost insoluble in conc. H2SO4 and organic solvents; the only polymers prepared from diamines having a hetero atom, such as S or P, dissolved in conc. H2SO4. Therefore, it is probable that the phosphorus-containing polyamide-imide obtained from bisimide-carboxylic acid has a better solubility than that prepared from bisamide-anhydride.
Thermal properties of polymers Thermal stability of the polyamide-imide was evaluated by thermogravimetric analysis (TGA) and differential thermal analysis (DTA), both in air and in nitrogen. Typical TGA and DTA curves are illustrated in Fig. 2; thermal behaviour data are listed in Table 3. The T G A data indicate that the thermal decomposition of phosphorus-containing polyamideimides proceeded in two stages in air, the first in the range 4(~-500 ° and the second in the range 530-570 ~. DTA shows exothermal peaks in those temperature
Table 2. Preparation of polyamide-imides*
~/~,.dt
Poly. No.
Bisimidecarboxylic acid
Diacetamide
Yield (%)
(dl/g)
Calc.
N% Found
P'%
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20
BCIMP BCIMP BCIMP BCIMP BCIMP BCIBP BCIBP BCIBP BCIBP BCIBP BCICP BCICP BCICP BCICP BCICP BCIB BCIB BCIB BCIB BCIB
DA D DADM DADE DADS DADPO DAD DADM DADE DADS DADPO DAD DADM DADE DADS DADPO DAD DADM DADE DADS DADPO
75 66 61 69 63 65 50 58 67 69 69 56 54 69 75 78 63 83 66 57
0.25 -0.28 0.285 0.23 0.29 -0.29 0.30 0.32 0.29 --0.27 0.295 0.195 0.27 --0.30 0.23
7.54 7.40 7.38 6.94 6.96 7.14 7.01 7.00 6.60 6.66 6.91 6.79 6.78 6.40 6.42 7.91 7.75 7.73 7.25 7.27
6.67 7.39 6.42 5.75 5.22 6.39 6.18 7.05 5.03 6.79 6.30 6.91 6.80 5.33 5.17 6.78 6.55 6.58 6.87 7.01
Calc.
Found
4.17 4.13 4.09 3.92 4.08 3.92 3.84 3.42 7.70 7.42 3.95 3.75 3.88 3.67 3.87 3.88 3.65 3.33 7.36 7.13 3.79 3.21 3.72 3.08 3.71 3.50 3.51 3.08 6.89 6.38 . . . . ----3.97 3.46
* Temperature: 320-325 °, Time: 2hr, Pressure: l~25Torr. Molar ratio: 1.0 Idiacetamide/bisimide-carboxylic acid). "1"Measured in conc. H2SO4 at 30°, C = 0.2 g/dl. :~ Measured in DMA at 30°, C = 0.2 g/dl.
78
M. SATO and M. YOKOYAMA
100
80 1
g 60 m
~
.IE
40
11 N 20 o x LI.I
1 $~
0
I
200
I
I
I
I,
I
600
70(
1800
I
300 400 500 Temp (°C)
I
|
I
1600 1400 1200 Wave number(cm "1)
1000
Fig. 2. TGA and DTA curves of polyamide-imides in air. Poly. No. 1, 6, 11 and 16 in Table 2.
Fig. 3. i.r. Spectra of the residual polymers after thermal decomposition. Poly~ No. 6.
ranges and that the temperature of the peak in the first thermal degradation rises in the order of alkyi groups of @ , Bu and Me. In the second thermal decomposition, DTA shows rapid exotherms, followed by a steep weight loss in the polymers observed by TGA. Non-phosphorus polyamide-imide exhibits an exothermal peak at around 620 ° and rapidly degrades in one step. In nitrogen, the pyrolysis of
phosphorus-containing polyamide-imides also proceeds in the range of 460-520 ° and at above 630 °, in two steps. Beyond the former temperature, the degradation proceeds relatively more slowly. The decomposition temperature of phosphorus-containing polyamide-imide is higher than that of non-phosphorus polyamide-imide, both in air and in nitrogen. The weight of thermal residue of polymers at 700 ° is found to be higher for treatment in nitrogen than in air, and in phosphorus-containing polymers than in non-phosphorus polymers. It appears that phosphorus-containing polyamide-imides have good thermal stability, in agreement with the result for the polymer obtained from bisamide-anhydride and aromatic diamines 1-10]. i.r. Spectra of thermal residual polymers after heat treatment are shown in Fig. 3. It was found that, as the temperature of thermal treatment was elevated, the absorption of the imide ring and amido group decreased and disappeared at above 600 °. A new absorption band based on C = N appears around 1600 c m - ) and the i.r. spectra are analogous to those of the phosphorus-containing polyamide-imides prepared from bisamide-anhydride. Most of the absorption bands in the i.r. spectra of polymers were not observed in the residue after thermal decomposition at > 600 °. It has been considered that the weight of thermal residue up to 700 ° is related to flame-resistance, so that these polymers are flame retardants [3, I1]. The phosphorus-containing polyamide-imides were selfextinguished instantly after the flame was removed. The non-phosphorus polyamide-imides also showed self-extinguish behaviour and stopped burning after about 1 or 2 sec.
Table 3. Thermal behaviour data of polyamide-imides Poly. No. 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20
Weight residue at 700" (~"o) in air in N 2 46 43 35 14 64 42 39 32 18 61 30 14 18 12 47 0 0 1 13 27
69 68 71 56 75 77 81 64 64 81 76 60 67 75 75 66 67 61 59 71
Texo*' (~C)
490 490 500 485 475 435 450 450 445 455 425 425 410 425 450 ----460
Decomp. tempt (°C) in air in N 2 491 520 504 464 475 476 481 504 441 456 435 440 434 427 443 515 502 454 515 480
508 518 533 468 481 486 519 499 465 476 470 449 469 474 461 522 506 479 506 490
* Temperature of the first exothermal peak in DTA. t Decomposition temperature at which 10~ weight loss was observed in TGA at the heating rate of 10°/min.
Acknowledgements--The authors are indebted to Mr Ohata for elemental analyses.
Preparation of phosphorus-containing potymers--XV REFERENCES
1. N. A. Adrova, M. M. Koton and L. K. Prokhorova. Vysokomolek. Soedin. B 13, 235 (1971). 2. H. Sivriev and G. Borissov. Europ. Polym. J. 13, 25 (1977). 3. M. Sato, T. lijima, T. Uchida and M. Yokoyama, Kohunshi Ronbunshu. In press. 4. H. Vogel and C. S. Marvel, J. Polym. Sci. A 1, 1531 (1963). 5. A. M. VanArendonk and E. C. Kleiderer, J. Am. chem. Soc. 62, 3521 (1940).
79
6. C. Holstead and A. H. Lamberton, J. Chem. Sot'. 1952. 1886. 7. R. T. Foster and C. S. Marvel, J. Pol3"m. Sci. A 3, 417 0965). 8. T. Ya. Medved'. T. M. Frunze, C.-M. Khu. V. V. Korshak and M. I. Kabachnik, Polynwr Sci. USSR 5, 386 (1964). 9. Y. Yamazaki and T. Suzuki, Nippon Kagaku Kaishi 1812 (1973). 10. M. Seita, M. Sato and M. Yokoyama, submitted for publication in Kohunshi Ronhunshu. I I. D. W. van Kreveln, Polymer 16, 615 (1975).
(X)14-3057 7901014)075502.00 0
PREPARATION OF PHOSPHORUS-CONTAINING POLYMERS--XV PREPARATION OF PHOSPHORUS-CONTAINING POLYAMIDE-IMIDES N,N'-BIS(4-CARBOXYPHTHALIMIDO)-3,3'-DIPHENYLALKYLPHOSPHINE AND AROMATIC DIACETAMIDES
FROM OXIDE
M. SATO and M. YOKOYAMA Department of Industrial Chemistry, Kogakuin University, 1-24-2, Nishishinjuku, Shinjuku-ku, Tokyo 160, Japan (Received 17 April 1978) Abstract--Phosphorus-containing polyamide-imides were prepared from N,N'-bis(4-carboxyphthalimido)-3,Y-diphenylalkylphosphine oxide and aromatic diacetamido derivatives by acidolysis; the reaction conditions are discussed. The resulting polymers were fairly soluble in DMA, DMF and conc. H2SO4; the reduced viscosities of polymers in DMA or cone. H2SO4 (0.2g/dl) at 30° were 0.19-0.32. The phosphorus-containing polymers have good thermal stability, and are self-extinguished immediately after the flame is removed. Most of the i.r. absorption bands of polymers vanished on heating at above 600°.
We have reported [3] the preparation of phosphorus-containing polyester-imide from N,N'-bis(4-carboxypht halimido)-3,3'-diphenylalkylphosphine oxide (BCIAP), having a preformed phthalimide ring, and various aromatic diacetoxy compounds by acidolysis; good thermal stability and flame resistance were shown. In the present work, as a continuation of studies on the preparation of phosphorus-containing polymers, polyamide-imides were synthesized from BCIAP and various aromatic diacetamido derivatives in vacuo; their properties were investigated and compared with those of analogous non-phosphorus polymers.
INTRODUCTION
Linear aromatic heterocyclic polymers, such as potyimide, polyester-imide and polybenzimidazole, have been reported by many authors. These polymers have good thermal stability but exhibit poor solubility in most organic solvents. Polymers containing phosphorus in the main chain are heat and flame resistant, and are soluble in polar aprotic solvents such as D M F and DMSO. Recently, phosphorus-containing polyimide[l] and polybenzimidazole[2] were prepared and their properties were disclosed.
0 II
0 tl
0
+ 0
0 0 II
0 .
--CH3COOH
.
.
0 II
.
0
R :
H 3CCOHN-R'--NHCOCH 3
o
CH3 ~ C4H9 ~
R' : (DAD)
(DADSI
(DADM) O
'
" ~
CH3~-/ (DAOPO) 75
(DADE)
76
M. SATO and M. YOKOYAMA RESULTS
EXPERIMENTAL
Diacetamides Aromatic diacetamido derivatives were obtained by the usual procedure for acetylation of aromatic diamines. Their melting points were as follows: 4,4'-diacetamidodiphenyl (DAD), m.p. 339-340 ~ (lit. [4] 340-343); 4,4'-diacetamidodiphenyl sulfone (DADS), m.p. 288~290 ° (lit. [5] 275-278"): 4,4'-diacetamidodiphenylmethane (DADM), rap. 233.5-235.0 '' (lit. [6] 233"): 4,4'-diacetamidodiphenyl ether (DADE), m.p. 231-232 ~' (lit. [7] 228-229"); 3,3'-diacetamidodiphenylmethylphosphine oxide (DADPO), m.p. 274-275.5" (lit. [8] 275-277").
Preparation of hisimide-carhoxylic acid monomers N,N'-bis ( 4- carhoxyphthalinfido ) - 3,3' - diphenylcyclohexylphosphine oxide (BCICP) To a solution of bis(3-aminophenyl)cyclohexylphosphine oxide (0.01 mole) in 15 ml of DMF. trimellitic anhydride (0.021 mole) was added and the reaction mixture was stirred for 20 hr at room temperature. It was poured into a large excess of water. The white precipitate was collected by filtration, repeatedly washed with water and dried in vacuum at room temperature. The product was dissolved in 20 ml of m-cresol and the solution was refluxed for 2 hr. It was then cooled and evaporated to dryness under reduced pressure. The resulting solid was recrystallized from acetone; yield 720,, m.p. 334 '~ (DTA method). Anal. Calcd. for C3~H27N2OgP: C, 65.26"~: H, 4.08°0: N, 4.23";,: P. 4.68"~;. Found: C, 64.34°~,; H, 4.42't,,: N. 4.09°%; P. 4.79~. N,N'-Bis(4-carhoxyphthalimido)-3,3'-diphenyhnethylphosphine oxide (BCIMP) and N,N'-bis(4-carboxyphthalimido)33'-diphenylbutylphosphine oxide (BCIBP) These substances were prepared by the method described above. Each product was heated in refluxing acetone. washed several times with acetone, and dried over phosphorus pentoxide in t~acuo. BCIMP: yield 62°,~,, m.p. 323" (DTA method). Anal. Calcd. for C3~H~gN2OgP: C. 62.63°~; H. 3.20°o; N, 4.71°0; P. 5.22°o. Found: C. 60.97°o; H, 3.41°%; N, 4.47°~,; P, 5.30°. BCIBP: yield 780,;. m.p. 328 ~"(DTA method). Anal. Calcd. for C34H25N2OgP: C, 64.17°o H. 3.93°0: N. 4.40°,,: P, 4.8700. Found: C. 64.02°,,; H. 4.29°,,; N. 4.70°o; P. 4.72°0.
AND
DISCUSSION
Preparation of monomer Previously [3], B C I M P and BCIBP were synthesized via bisamic acid from bis(3-aminophenyl)alkylphosphine oxide and trimellitic anhydride in 1:2 molar ratio. In the present paper, B C I A P was prepared by a modified method. The bisamic acid in m-cresol was refluxed for 6 hr and gave the corresponding bisimide-carboxylic acid in 62-78yo yield. Their structures were identified by elemental analyses and i.r. spectra. Experimental analyses agreed with calculated, i.r. Spectra showed the characteristic absorption bands of P--K) at l l 5 0 c m -1, P---C6H s at 1420cm -1, C6H5 at 1580 and 1480cm -1, C - - N at 1370cm -1 and imide ring at 1720 and 1780cm -1. It is considered that the shifts to lower frequencies of the absorption bands from the expected values (about 20 cm-1) are due to the increasing conjugation resulting from electronegative groups, such as P = O or C---O of carboxylic acid and imide ring, and aromatic ring. The absorption band corresponding to O H streching and a shoulder based on C = O of carboxyl group were observed at 2500 to 3000cm-1 and near 1700 c m - 1 respectively.
Phosphorus-containing polyamide-imide It has already been reported that polyamide-imides are synthesized from bisimide-carboxylic acid containing naphthalene ring and aromatic diacetamides by acidolysis without catalyst under reduced pressure and that they have good thermal stability; polymerization conditions were not reported in detail [9]. We now report the syntheses of phosphorus-containing polyamide-imides by acidolysis from bisimidecarboxylic acid and aromatic diacetamido derivatives. Polymerization conditions and physical properties are also discussed.
0.3
3,Y-[N,N'-bis( 4-carboxyphthalimido) ]benzophenone (B C IB) This substance was synthesized by the method described previously [3]: yield 7400. m.p. 331" (DTA method). Pol)'condensation A typical procedure for obtaining the polyamide-imide is described. BCIBP and DADS were mixed and charged into a four-necked flask. Heating for 2 hr at 320-325 ~ in vacuo (15-25 Torr) gave a dark-brown solid. When cooled, the resulting polymer was washed sequentially with stirring in DMF and then in hot acetone, and dried over phosphorus pentoxide at 150~ at reduced pressure. Characterization of polymers Infrared spectra were obtained on Jasco Model IR-S i.r. spectrometer. Thermal analyses were carried out with Shimadzu Model DT-30 thermal analyser in air and in nitrogen (30 ml/dl) and heating at a rate of 10°/min.
--~ 0.2 5 "El
/
0.1
i
0
i
i
i
1.0 1.5 2.0 Mota~" ratio (DADS/BC[BP) 0.5
Fig. 1. Effect of molar ratio on polycondensation of DADS and BCIBP. q,.a: Measured in DMA at 30% C = 0.2 g/dl.
77
Preparation of phosphorus-containing polymers--XV Table 1. Effect of reaction time and temperature on polycondensation of DADS and BCIBP* Time (hr)
Temp (°C)
Yield (%)
0.25 0.5 1.0 1.5 2.0 3.0 5.0 2.0 2.0 2.0
300-305 300-305 300-305 300-305 300-305 300-305 300-305 280--285 320-325 340-345
48 60 61 65 67 63 60 59 67 65
qr,,(t (dUg) 0.07 0.14 0.20 0.25 0.29 0.28 0.28 0.26 0.31
*Molar ratio: 1.0 (=DADS/BCIBP), Pressure: 15-25 Torr. "t Measured in DMA at 30 '~. C = 0.2 g/dl.
First, polymerization conditions were investigated under reduced pressure (15-25 Torr) by using BCIBP and D A D S in order to find the optimum conditions for the preparation of phosphorus-containing polyamide-imides. These results are presented in Fig. 1 and Table 1. Table 1 shows that the reduced viscosity is fairly constant for reaction times of over 2 hr and it increases with rise in reaction temperature. The polymers obtained at temperatures > 3 3 0 ° did not dissolve in D M F , conc. H2SO4 etc. From Fig. 1, viscosity is highest at the molar ratio of 1.0. This result suggests that the preparation of phosphorus-containing polyamide-imides should be carried out under following conditions: Molar ratio of 1.0; reaction time of 2 h r ; reaction temperature of 320-325 °. Under these conditions, melt polycondensations were run and the data are summarized in Table 2. Polyamideimides having a reduced viscosity in the range of
0.19-0.32 were obtained in a yield of 50--8Yk;,. Elemental analyses of various polyamide-imides agreed well with calculated values. The i.r. spectra of polymers showed that the absorption bands of carboxyt group disappeared and that of amido group appeared at 1660 and 1520cm-1. Non-phosphorus polymers showed the absorption band of C~--~-O at 1660cminstead of that based on P - - O at l l 5 0 c m - ~ . The formation of polyamide-imides were confirmed from these data. Most of the phosphorus-containing polymers dissolved in polar aprotic solvents such as D M F , DMA, and DMSO, and conc. H 2 S O 4, while non-phosphorus polymers were insoluble in organic solvents but soluble in conc. H2SO 4. Thus the phosphorus-containing polymers have better solubility in organic solvents than the non-phosphorus polymers. We have also prepared phosphorus-containing polyamide-imides from bisamide-anhydride and aromatic diamines by melt polycondensation[10]. These polymers were almost insoluble in conc. H2SO4 and organic solvents; the only polymers prepared from diamines having a hetero atom, such as S or P, dissolved in conc. H2SO4. Therefore, it is probable that the phosphorus-containing polyamide-imide obtained from bisimide-carboxylic acid has a better solubility than that prepared from bisamide-anhydride.
Thermal properties of polymers Thermal stability of the polyamide-imide was evaluated by thermogravimetric analysis (TGA) and differential thermal analysis (DTA), both in air and in nitrogen. Typical TGA and DTA curves are illustrated in Fig. 2; thermal behaviour data are listed in Table 3. The T G A data indicate that the thermal decomposition of phosphorus-containing polyamideimides proceeded in two stages in air, the first in the range 4(~-500 ° and the second in the range 530-570 ~. DTA shows exothermal peaks in those temperature
Table 2. Preparation of polyamide-imides*
~/~,.dt
Poly. No.
Bisimidecarboxylic acid
Diacetamide
Yield (%)
(dl/g)
Calc.
N% Found
P'%
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20
BCIMP BCIMP BCIMP BCIMP BCIMP BCIBP BCIBP BCIBP BCIBP BCIBP BCICP BCICP BCICP BCICP BCICP BCIB BCIB BCIB BCIB BCIB
DA D DADM DADE DADS DADPO DAD DADM DADE DADS DADPO DAD DADM DADE DADS DADPO DAD DADM DADE DADS DADPO
75 66 61 69 63 65 50 58 67 69 69 56 54 69 75 78 63 83 66 57
0.25 -0.28 0.285 0.23 0.29 -0.29 0.30 0.32 0.29 --0.27 0.295 0.195 0.27 --0.30 0.23
7.54 7.40 7.38 6.94 6.96 7.14 7.01 7.00 6.60 6.66 6.91 6.79 6.78 6.40 6.42 7.91 7.75 7.73 7.25 7.27
6.67 7.39 6.42 5.75 5.22 6.39 6.18 7.05 5.03 6.79 6.30 6.91 6.80 5.33 5.17 6.78 6.55 6.58 6.87 7.01
Calc.
Found
4.17 4.13 4.09 3.92 4.08 3.92 3.84 3.42 7.70 7.42 3.95 3.75 3.88 3.67 3.87 3.88 3.65 3.33 7.36 7.13 3.79 3.21 3.72 3.08 3.71 3.50 3.51 3.08 6.89 6.38 . . . . ----3.97 3.46
* Temperature: 320-325 °, Time: 2hr, Pressure: l~25Torr. Molar ratio: 1.0 Idiacetamide/bisimide-carboxylic acid). "1"Measured in conc. H2SO4 at 30°, C = 0.2 g/dl. :~ Measured in DMA at 30°, C = 0.2 g/dl.
78
M. SATO and M. YOKOYAMA
100
80 1
g 60 m
~
.IE
40
11 N 20 o x LI.I
1 $~
0
I
200
I
I
I
I,
I
600
70(
1800
I
300 400 500 Temp (°C)
I
|
I
1600 1400 1200 Wave number(cm "1)
1000
Fig. 2. TGA and DTA curves of polyamide-imides in air. Poly. No. 1, 6, 11 and 16 in Table 2.
Fig. 3. i.r. Spectra of the residual polymers after thermal decomposition. Poly~ No. 6.
ranges and that the temperature of the peak in the first thermal degradation rises in the order of alkyi groups of @ , Bu and Me. In the second thermal decomposition, DTA shows rapid exotherms, followed by a steep weight loss in the polymers observed by TGA. Non-phosphorus polyamide-imide exhibits an exothermal peak at around 620 ° and rapidly degrades in one step. In nitrogen, the pyrolysis of
phosphorus-containing polyamide-imides also proceeds in the range of 460-520 ° and at above 630 °, in two steps. Beyond the former temperature, the degradation proceeds relatively more slowly. The decomposition temperature of phosphorus-containing polyamide-imide is higher than that of non-phosphorus polyamide-imide, both in air and in nitrogen. The weight of thermal residue of polymers at 700 ° is found to be higher for treatment in nitrogen than in air, and in phosphorus-containing polymers than in non-phosphorus polymers. It appears that phosphorus-containing polyamide-imides have good thermal stability, in agreement with the result for the polymer obtained from bisamide-anhydride and aromatic diamines 1-10]. i.r. Spectra of thermal residual polymers after heat treatment are shown in Fig. 3. It was found that, as the temperature of thermal treatment was elevated, the absorption of the imide ring and amido group decreased and disappeared at above 600 °. A new absorption band based on C = N appears around 1600 c m - ) and the i.r. spectra are analogous to those of the phosphorus-containing polyamide-imides prepared from bisamide-anhydride. Most of the absorption bands in the i.r. spectra of polymers were not observed in the residue after thermal decomposition at > 600 °. It has been considered that the weight of thermal residue up to 700 ° is related to flame-resistance, so that these polymers are flame retardants [3, I1]. The phosphorus-containing polyamide-imides were selfextinguished instantly after the flame was removed. The non-phosphorus polyamide-imides also showed self-extinguish behaviour and stopped burning after about 1 or 2 sec.
Table 3. Thermal behaviour data of polyamide-imides Poly. No. 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20
Weight residue at 700" (~"o) in air in N 2 46 43 35 14 64 42 39 32 18 61 30 14 18 12 47 0 0 1 13 27
69 68 71 56 75 77 81 64 64 81 76 60 67 75 75 66 67 61 59 71
Texo*' (~C)
490 490 500 485 475 435 450 450 445 455 425 425 410 425 450 ----460
Decomp. tempt (°C) in air in N 2 491 520 504 464 475 476 481 504 441 456 435 440 434 427 443 515 502 454 515 480
508 518 533 468 481 486 519 499 465 476 470 449 469 474 461 522 506 479 506 490
* Temperature of the first exothermal peak in DTA. t Decomposition temperature at which 10~ weight loss was observed in TGA at the heating rate of 10°/min.
Acknowledgements--The authors are indebted to Mr Ohata for elemental analyses.
Preparation of phosphorus-containing potymers--XV REFERENCES
1. N. A. Adrova, M. M. Koton and L. K. Prokhorova. Vysokomolek. Soedin. B 13, 235 (1971). 2. H. Sivriev and G. Borissov. Europ. Polym. J. 13, 25 (1977). 3. M. Sato, T. lijima, T. Uchida and M. Yokoyama, Kohunshi Ronbunshu. In press. 4. H. Vogel and C. S. Marvel, J. Polym. Sci. A 1, 1531 (1963). 5. A. M. VanArendonk and E. C. Kleiderer, J. Am. chem. Soc. 62, 3521 (1940).
79
6. C. Holstead and A. H. Lamberton, J. Chem. Sot'. 1952. 1886. 7. R. T. Foster and C. S. Marvel, J. Pol3"m. Sci. A 3, 417 0965). 8. T. Ya. Medved'. T. M. Frunze, C.-M. Khu. V. V. Korshak and M. I. Kabachnik, Polynwr Sci. USSR 5, 386 (1964). 9. Y. Yamazaki and T. Suzuki, Nippon Kagaku Kaishi 1812 (1973). 10. M. Seita, M. Sato and M. Yokoyama, submitted for publication in Kohunshi Ronhunshu. I I. D. W. van Kreveln, Polymer 16, 615 (1975).