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Thermo-reactive polymers with a poly-(p-phenylenoxide) structure produced from bis-phenols and formaldehyde
1990
Yu. P. VOaOV'EV eta/.
9. R. MARX, J. chim. phys. et phys.-chim, biol. 62: 767, 1965; R. MARX and M. R. BEN. SASSON, J. chim. phys. et phys.-chim, biol. 57: 673, 1960 10. J. HAJIMOTO, N. TAMURA and S. OKAMOTO, J. Polymer Sci. A3: 255, 1965 11. R. J. ABRAHAM, H. W. MELWILLE, D. W. OVEN~I.I. and D. H. WHIFFEN, Trans. Faraday Soc. 54: 1133, 1958 12. H. FISHER, J. Polymer Sei. B2: 529, 1964 13. V. K. MILINCHUK and S. Ya. PSHEZHETSKII, Vysokomol. soyed. 6: 1605, 1964 (Translated in Polymer Sei. U.S.S.R. 6: 9, 1778, 1964) 14. A, OKU, M. OKANO and R. ODA, Bull. Chem. Soc. Japan 37: 572, 1964
THERM0-REACTIVE POLYMERS WITH A POLY-(p-PHENYLEN0XIDE) STRUCTURE PRODUCED FROM bis-PHENOLS AND FORMALDEHYDE* YU. P. VOROB'EV, V . A . SERGEYEV, V. V. KORSHAK a n d V. G. D.~_z, o v Institute of Organometallic Compounds, U.S.S.R. Academy of Sciences
(Received 15 July 1966) THe. large t h e r m a l stability of low molecular weight (m.w.) [1-3] a n d high m.w. [4-7] compounds, with a p h e n y l e n e oxide structure, is well known. This p a p e r reports the synthesis of polymers from f o r m a l d e h y d e a n d bis-phenols h a v i n g a poly-(p-phenylene oxide) s t r u c t u r e
_oi: o. in which n : 0, 1, 2, 4. Jr These polymers were used a t t h e same time to a t t e m p t a n assessment of t h e crosslinking f r e q u e n c y a n d its effect on t h e properties of crosslinked polymers. P r e l i m i n a r y e x p e r i m e n t s h a d established t h a t alkalis (NaOH, K O H ) were n o t efficient catalysts for the f o r m a l d e h y d e addition to the bis-phenols. :By using a m m o n i a as catalyst, it b e c a m e possible to o b t a i n t h e r m o - r e a c t i v e polymers o f a n i n d e t e r m i n a t e structure, also containing nitrogen. I n t h e consideration of the a m m o n i a , f o r m a l d e h y d e a n d phenol condensation as a typical case of the Mannich reaction [8] we used the mono-functional d i m e t h y l * Vysokomol. soyed. A9: No. 8, 1763-1767, 1967. t The report on tho synthesis of bis-phenols will be published in Zhur. org. khim. later.
Thermo-reactive polymers with poly(p-phenylenoxide) structure
1991
amine instead of the trifunctional ammonia to synthesize the Mannich bascs (I), in a manner similar to the numerous condensations of various phenols, from oxyphenylene bis-phenols and formaldehyde with dimethylamine. _o H /-.,
. J
I
t
N--CH,
~/H ,
HaC--b(
CH,CHa
CH3CH3 I
Table 1 lists the characteristics of the produced compounds. The infrared spectra of a,to-dihydroxytetra-(p-phenylene oxide) and of the 3Iannich bases made from it are shown in Fig. 1. The valence oscillation band of the hydroxyl group TABLE 1.
Compound
I from n=0 I from n: 1 I from n = 2 I from n=4 :From p h e n o l *
~/IANI~'ICH B A S E S
m.p., °C
136-137 182-184 Resin Resin Liquid
USED
AS S T A R T I N G
MATERIAL
Elemental
analysis,
calculated
I
C
It
N
68"4 70"5 72"0 73"5 70"5
7"6 6-8 6'4 5-8 9-2
8.8 6"8 5'6 4"1 11-7
found C
i
68-7 70.3 I 71.3 72-3 i 70.2
H
N
7-9 6-9 6.2 5.8 9.1
8"6 6.7 5'2 4"5 11.0
* Prepared for comparison ace. to method [14], using 1.5 mole formaldehyde per 1.0 mole phenol.
Call be seen to shift during the change from the Mamlich base towards the longer wavelength; this can be explained by the formation of a hexavalent chelate ring in which the hydrogen bond takes part, [15]. The data of Table 1 and Fig. 1, together with the numerous literature data [8-14], indicate the M:amlich base to have the structure shown in formula (I), in which n=0,1,2,4. We had earlier noticed the tendency of the phenolic Mannich base to react with nueleophilic reagents [16-18]. One of the amine fragments in particular could be replaced by another [19-20]. Their reactions with phenols were similar to those with amines [21], but there was some ring substitution in the case of phenols [22]. The produced diarylmethanes were often found to be secondary products of the Mamfich reaction in particular [23, 24]. It was also noticed t h a t a free ortho- or para-position present on the phenolic Ma.lmich bases resulted in polymerization combined with ring substitution [16, 25]. The fact that polymers are produced from phenols and hexamethylenetetramine is, after all, well known [26].
Yu. P. VOROB'EVet
1992
al.
The heating of the Mannich bases produced b y us gave the polymers: OH
OH
OH
OH
O
CH,N(CH,),
(The polymer was probably produced via the stage of the o-quinone methide [16,
17-25, 27]). Dimethylamine separated out at 150°C; 2-3 hr were required at 200-210°C for the reaction to be complete, and 25-30 rain at 230-240°C. The rate of polycondensation was 2-2.5 times slower in the case of phenol than with the hydroxyphenylenie bis-phenols. The polymers were insoluble, coloured, non-melting and brittle products. Figure 2 shows the % conversion as a function of time on the
8O
OH
2J
25
~ 31
Fro. I
' / 5 ' 37 ~,/O2,cm -'
M__X.=~v.--X
/
"~ ~0 ~x
i
!
l 2
I
I
3
T[me,hr
Fio. 2
Fro. 1. Infrared spectra: 1--~,eo-dihydroxytetra-(p-phcnylene oxide); 2--Marmich base made from it; 3--polymer produced from this Mannich base. Fro. 2. °/o Polycondensation of the Mannich base from a,oJ-dihydroxytetra-(p-ph enylene oxide) at 2104-5°C as a function of weight loss. basis of weight change during the polycondensation of the Mannich base from a,~o-dihydroxytetra-(p-phenylene oxide) at 210 _+5°C. The elemental analysis of the polymers produced b y heating of the respective Mannich bases at 210 + 5°C for 3-4 hr is given in Table 2. The infrared spectra of the polymers obtained on decomposing the Mannich base are shown in Fig. 1, curve 3. The composition can be seen to be incomplete according to the spectral data and Table 2.
Thermo-reactive polymers with poly-(p-phenylenoxide) structuro
1993
T h e % c o n v e r s i o n b y t h e p o l y c o n d e n s a t i o n , calculated f r o m t h e changes o f n i t r o g e n c o n t e n t before ( N - m o n o m e r ) a n d a f t e r ( N - p o l y m e r ) heating, is s h o w n in T a b l e 2 w i t h o u t correction for weight losses. T A B L E 2. POLYMERS PRODUCED FROM MANNICH BASES
Polycondensation efficiency, N M Np x 100, NM
% By analysis
No.
Polymer
-
% Weight loss
Carbon
-
yield, calc. [ t I f°und
%
%
I
1 2 3
From I with n = O From I with n = 1 *As 2 but addition-! al heating at 250°C From I with n = 2 From I with n = 4 From phenolic Mannich base
4 5 6
68.5 72"0
5.7 5"3
3"6 2"5 [
58.2 63"5
11-5 8"0
9'5 7.5
59.1 56.8
72'0 72"9 74"1
5.0 50 4"7
1"2
m
1"4 0.7
73.0 85.0
3.8 4.5 2"2
1.5 5.0 2"5
55.8 52-6 48"2
69'0
6"3
3"6
66"7 i
* See experimental part. t According to formula: Np-.~(CHs)sN~H --(45/14)Np=3.2 I~p. 14
F i g u r e 3 shows t h e t h e r m o m e c h a n i c a l curves of p o l y m e r s p r o d u c e d on t h e
appropriate [29] i n s t r u m e n t w i t h a c o n s t a n t stress of 0.8 k g / c m ~ a n d a t e m p e r a t u r e g r a d i e n t o f 2°C/rain. T h e results o f t h e t h e r m o g r a v i m e t r i e a n a l y s i s o b t a i n e d o n
100
50 ,. /
0
~s
- ,......x,.Y,..
j °
"
_I--
tO0
200
JO0
000
500
6'00
70077,"g
FIG. 3. Thermomechanical curves of polymers produced from I. n: •--0; 2--1; 3--2; 4--4; 5--polymer produced from phenol via the Mannich base. a t h e r m i o n i c b a l a n c e B-60 m a d e b y t h e firm " D a m " are s h o w n in Fig. 4; t h e y were o b t a i n e d b y h e a t i n g t h e s a m p l e s in a h e l i u m s t r e a m a t a c o n s t a n t r a t e o f 5°C/rain. T h e d e f o r m a t i o n c a n b e seen to be slight u p to 500°C (Fig. 3), a l t h o u g h
Y u . P. VOROB'~V et al.
1994
in the range of intense decomposition of the polymers (Fig. 4). The temperature elevation thus did not cause the polymer to change to the highly elastic state, but caused it to decompose. The crosslinking intensity changes in the selected range did not result in any marked change of the thermomechanical properties of the polymers. This could be due to the fairly high crosslinking density. The thermogravimetric curves of Fig. 4 show that the intese decomposition of the polymers started above a temperature of about 320°C. Before that the weight losses were due to decomposition of the residual amino groups present in the polymers. The data obtained from the curves was used to give the weight losses of polymers before the start of intense decomposition (320°C) in Table 2, together with those calculated from the residual N-content of the polymers and under conditions of complete decomposition of the Mannich bases. There was good agreement between the found and calculated weight losses. This indicated that the weight losses of the polymer up to about 320°C were due to further decomposition of the Mannich bases. In the temperature range 320600°C there was intense decomposition o~ all the polymers which resulted in a high yield of a carbonaceous residue. This yield is also given in Table 2 after thermal treatment of the polymers up to 900°C, taking into account the weight loss up to 320°C.
~N. .N
I
200
I
I
000
I
GO0
;
1
I
800 ~
Fro. 4. Thermogravimetric curvcs of the polymers produced from I. n: 1--0; 2--I; 3--2; 4--4; 5--I (polymer further heated at 250°C to constant weight). The results given here are evidence of an increasing poly-(p-phenylene oxide) segment length, and consequently of the lower erosslinking density in the polymer, slightly reducing the carbon yield. This change is rather small compared with the carbon yield from polymers containing polymethylene segments of different length between the :phenol rings, as found by two of the authors in eonjmmtion with Doroshenko [30]. The explanation for this could be that the compounds with a phenylene oxide structure tend towards compacting at 400-600°C rather than decomposition.
Thermo-reaetive polymers with poly-(p-phenylenoxide) structure
1995
EXPERIMENTAL Synthesis of I with n ~ 0. 3 g of the respective bis-phenol and 3.4 ml of an aqueous 37% CH~O solution were mixed at 20°C a n d 5.4 ml of a 44% aqueous dimethylamine solution were added dropwise. The precipitate was filtered off the next day, washed with water and dried. This yielded 4-2 g (89.5°/o of theory) of an impure product, which was recrystallized from ethanol and gave 2.8 g of a substance with m.p. 136-137°C. Tjhe results of analysis are listed in Table 1. " Synthetis of I with n ~ 1. 2-9 g of the respective bis-phenol was dissolved in 6-0 ml dioxane, 2.4 ml of a 37 % aqueous CH20 solution were poured to it at 20°C and then 4- 8 ml of a 44 % dimethylamine solution. This was diluted the next day with water and the forming precipitate filtered off, washed and dried. This yielded 4.0 g (98.0% of theory) of a product which was recrystallized from acetone. The final product weighed 1.8 g; m.p. 182-184°C. Its analysis is given in Table 1. Synthesis of I with n ~ 2. This was produced from 1-3 g of the respective bis-phenol, 6.0 ml dioxane and 0.8 ml of 37% aqueous CH~O solution b y mixing at 20°C. To the solution were added 2.0 ml of a 3 6 . 0 % dimethylamine solution, the whole was left to stand for 2 days and the resulting oil was separated with water. Decanting of the water left a tarry product which was dissolved in acetone, the solution was treated with carbon, the acetone boiled off, and the product then vacuum-dried. The yield was 1.3 g (74-0% of theory) of a resinous yellow mass. An a t t e m p t to recrystallize this failed. The analytical result is given in Table 1. Synthesis of I with n ~ 4 . 0.9 g of the bis-phenol was dissolved in 50 ml dioxane, 1 ml of an aqueous 37~o Ctt20 solution and of a 44% dimethylamine solution were adeed. The reaction progress was controlled b y analysis of the product for nitrogen. The reaction mass was kept at 20°C for one m o n t h and contained 3 . 3 % nitrogen (calculated content., N ~ 4 . 1 % ) . Another 0-5 ml of the reagents was added,' the solvent evaporated after 10 days standing under v a c u u m at 20°C and the product dried. This yielded 1.0 g (84.0% of theory) of a substance whose analysis is given in Table 1. Production of phenolic Mannich base. The procedure was that described for 2,4,6-tris(dimethylaminomethyl)-phenol [14]; 18.8 g phenol and 26.8 g 37% Ctt20 were mixed and 54.5 g of 44% dimethylamine solution were added dropwise so t h a t the temperature did not exceed 25°C. The reaction mixture was then heated for 1 hr on a steam bath and the oil formed was separated. Vacuum-drying yielded 22.0 g (60.0% of theory) e r a yellow oil; the analytical results can be found in Table l. Polycondensation of Mannich bases. This was carried out b y heating in a condenser test tube under a slow helium stream at 210~5°C to constant weight. One of the polymers (from I with n : 1) was further heated to 250°C until its weight became constant.
CONCLUSIONS (1) T h e r m o - r e a c t i v e p o l y m e r s w i t h d i f f e r e n t c r o s s l i n k i n g d e n s i t i e s w e r e p r o d u c e d f r o m 4 , 4 - d i h y d r o x y d i p h e n y l oxide, ~ , o J - d i h y d r o x y - t r i - , t e t r a - , a n d h e x a ( p - p h e n y l e n e oxide) a n d formaldehyde. (2) C h a n g e s o f t h e c r o s s l i n k i n g d e n s i t y i n t h e s y n t h e s i z e d p o l y m e r s d i d n o t result in a n y s u b s t a n t i a l changes of their t h e r m o m e c h a n i c a l properties a n d thermal stability.
Translated by K . A . ALLEN
1996
Yu. P. VOROB'EV et aL REFERENCES
1. V. HOPKINS a n d D. WILSON, Ind. Eng. Chem. Product. Res. a n d Development 3: 38, 1964 2. S. AFTERGUT, R. BLACKINTON and L. BROWN, Chem. a n d Chem. Ind., 1090, 1959 3. U.S. PatB. 2547679, 1951; 3083234, 1963; 3081355, 1963. Chem. Abstracts 45, 9081-D, 1951; 59, 8657-c, 1963; 59, 3835-e, 1963 4. J. COX, B. WRIGHT and W. WRIGHT, J. Appl. Polymer SeL 9: 513, 1965 5. H. HOYT, B. HALPERN, K. TSOW, M. BODNAR and W. TANNAR, J. Appl. Polymer Sci. 8: 1633, 1964 6. O. STAFFIN and C. PRICE, J. Am. Chem. Soc. 82: 3632, 1960 7. A. HAY, J. Polymer Sci. 58: 581, 1962 8. F. BLICKE, Organic Reactions, vo]. 1, 10, J. Wiley a n d Sons Inc. N. Y., 1942 9. W. CALDWELL and T. THOMPSON, J. Am. Chem. Soc. 61: 765, 1939 10. J. BURCKHALTER, F. TENDICK, E. JONES, W. HOLCOMB and A. RAWLINS, J. Am. Chem. Soc. 68: 1896, 1946 11. J. BURCKHALTER, J. Am. Chem. Soc. 72: 5309, 1950 12. F. BLICKE and F. McCARTHY, J. Organ. Chem. 24: 1061, 1959 13. J. BURCKHALTER, I. WELLS, and W. MAYER Tetrahedron Letters, 1353, 1964 14. H. BRUSON a n d W. McMULLEN, J. Am. Chem. Soe. 63: 270, 1941 15. A. BELLAMY, Infrared Spectra of Complex Molecules, 137, 148-151, Foreign Lit. Publishing House, 1963 16. J. BREWSTER and E. ELIEL, Organic Reactions, vol. 7, 99-197, J. Wiley and Sons, Inc., N. ¥ . 1953 17. P. GARDNER, H. SARRAFIZADEH and R. L. RAND, J. Am. Chem. Soc. 81: 3364, 1959 18. D. MOLHO, Bull. Soc. Chim. France, 1417, 1961 19. H. SNYDER and J. BREWSTER, J. Am. Chem. Soc. 70: 4230, 1948 20. I. THASING a n d C. WILLERSINN, Chem. Ber. 89: 1195, 1956 21. K. A Z U ~ A , T. KITAMURA, S. FUKUZAKI, a n d E. IMOTO, Kogyo Kagaku Zasshi 61: 1035, 1958; Chem. Abstr. 55: 22210-h, 27187-e, 1961 22. U.S. Pat. 2839586, 1958; Chem. Abstracts 53: 3157-i, 1959. 23. J. BURCKHALTER, V. STEPHENS, H. SCARROROUGH, J. BRIMGAR and W. EDGERTON, J. Am. Chem. Soc. 76: 4902, 1954 24. Brit. Pat. 1002272, 1965. Chem. Abstr. 63, 15066-f, 1965 25. E. ELIEL, J. Am. Chem. Soc. 73: 43, 1951 26. S. AGARWAL, M. SIVA SAMBON and S. AGARWAL, P a i n t Manufacture 36: 29, 1966 27. P. GARDNER, H. SARRAFIZADEH and R. R. BRANDON, J. Am. Chem. Soe. 81: 5515, 1959 28. B. L. TSETLIN, V. I. GAVRILOV, I. A. VELIKOVSKAYA and V. V. KOC1TKIN, Zavod. labor. 22: 3, 352, 1956 29. Yu. DOROSHENKO, V. KORSHAK and V. SERGEYEV, Plast. massy, No. 2, 33, 1966
Yu. P. VOaOV'EV eta/.
9. R. MARX, J. chim. phys. et phys.-chim, biol. 62: 767, 1965; R. MARX and M. R. BEN. SASSON, J. chim. phys. et phys.-chim, biol. 57: 673, 1960 10. J. HAJIMOTO, N. TAMURA and S. OKAMOTO, J. Polymer Sci. A3: 255, 1965 11. R. J. ABRAHAM, H. W. MELWILLE, D. W. OVEN~I.I. and D. H. WHIFFEN, Trans. Faraday Soc. 54: 1133, 1958 12. H. FISHER, J. Polymer Sei. B2: 529, 1964 13. V. K. MILINCHUK and S. Ya. PSHEZHETSKII, Vysokomol. soyed. 6: 1605, 1964 (Translated in Polymer Sei. U.S.S.R. 6: 9, 1778, 1964) 14. A, OKU, M. OKANO and R. ODA, Bull. Chem. Soc. Japan 37: 572, 1964
THERM0-REACTIVE POLYMERS WITH A POLY-(p-PHENYLEN0XIDE) STRUCTURE PRODUCED FROM bis-PHENOLS AND FORMALDEHYDE* YU. P. VOROB'EV, V . A . SERGEYEV, V. V. KORSHAK a n d V. G. D.~_z, o v Institute of Organometallic Compounds, U.S.S.R. Academy of Sciences
(Received 15 July 1966) THe. large t h e r m a l stability of low molecular weight (m.w.) [1-3] a n d high m.w. [4-7] compounds, with a p h e n y l e n e oxide structure, is well known. This p a p e r reports the synthesis of polymers from f o r m a l d e h y d e a n d bis-phenols h a v i n g a poly-(p-phenylene oxide) s t r u c t u r e
_oi: o. in which n : 0, 1, 2, 4. Jr These polymers were used a t t h e same time to a t t e m p t a n assessment of t h e crosslinking f r e q u e n c y a n d its effect on t h e properties of crosslinked polymers. P r e l i m i n a r y e x p e r i m e n t s h a d established t h a t alkalis (NaOH, K O H ) were n o t efficient catalysts for the f o r m a l d e h y d e addition to the bis-phenols. :By using a m m o n i a as catalyst, it b e c a m e possible to o b t a i n t h e r m o - r e a c t i v e polymers o f a n i n d e t e r m i n a t e structure, also containing nitrogen. I n t h e consideration of the a m m o n i a , f o r m a l d e h y d e a n d phenol condensation as a typical case of the Mannich reaction [8] we used the mono-functional d i m e t h y l * Vysokomol. soyed. A9: No. 8, 1763-1767, 1967. t The report on tho synthesis of bis-phenols will be published in Zhur. org. khim. later.
Thermo-reactive polymers with poly(p-phenylenoxide) structure
1991
amine instead of the trifunctional ammonia to synthesize the Mannich bascs (I), in a manner similar to the numerous condensations of various phenols, from oxyphenylene bis-phenols and formaldehyde with dimethylamine. _o H /-.,
. J
I
t
N--CH,
~/H ,
HaC--b(
CH,CHa
CH3CH3 I
Table 1 lists the characteristics of the produced compounds. The infrared spectra of a,to-dihydroxytetra-(p-phenylene oxide) and of the 3Iannich bases made from it are shown in Fig. 1. The valence oscillation band of the hydroxyl group TABLE 1.
Compound
I from n=0 I from n: 1 I from n = 2 I from n=4 :From p h e n o l *
~/IANI~'ICH B A S E S
m.p., °C
136-137 182-184 Resin Resin Liquid
USED
AS S T A R T I N G
MATERIAL
Elemental
analysis,
calculated
I
C
It
N
68"4 70"5 72"0 73"5 70"5
7"6 6-8 6'4 5-8 9-2
8.8 6"8 5'6 4"1 11-7
found C
i
68-7 70.3 I 71.3 72-3 i 70.2
H
N
7-9 6-9 6.2 5.8 9.1
8"6 6.7 5'2 4"5 11.0
* Prepared for comparison ace. to method [14], using 1.5 mole formaldehyde per 1.0 mole phenol.
Call be seen to shift during the change from the Mamlich base towards the longer wavelength; this can be explained by the formation of a hexavalent chelate ring in which the hydrogen bond takes part, [15]. The data of Table 1 and Fig. 1, together with the numerous literature data [8-14], indicate the M:amlich base to have the structure shown in formula (I), in which n=0,1,2,4. We had earlier noticed the tendency of the phenolic Mannich base to react with nueleophilic reagents [16-18]. One of the amine fragments in particular could be replaced by another [19-20]. Their reactions with phenols were similar to those with amines [21], but there was some ring substitution in the case of phenols [22]. The produced diarylmethanes were often found to be secondary products of the Mamfich reaction in particular [23, 24]. It was also noticed t h a t a free ortho- or para-position present on the phenolic Ma.lmich bases resulted in polymerization combined with ring substitution [16, 25]. The fact that polymers are produced from phenols and hexamethylenetetramine is, after all, well known [26].
Yu. P. VOROB'EVet
1992
al.
The heating of the Mannich bases produced b y us gave the polymers: OH
OH
OH
OH
O
CH,N(CH,),
(The polymer was probably produced via the stage of the o-quinone methide [16,
17-25, 27]). Dimethylamine separated out at 150°C; 2-3 hr were required at 200-210°C for the reaction to be complete, and 25-30 rain at 230-240°C. The rate of polycondensation was 2-2.5 times slower in the case of phenol than with the hydroxyphenylenie bis-phenols. The polymers were insoluble, coloured, non-melting and brittle products. Figure 2 shows the % conversion as a function of time on the
8O
OH
2J
25
~ 31
Fro. I
' / 5 ' 37 ~,/O2,cm -'
M__X.=~v.--X
/
"~ ~0 ~x
i
!
l 2
I
I
3
T[me,hr
Fio. 2
Fro. 1. Infrared spectra: 1--~,eo-dihydroxytetra-(p-phcnylene oxide); 2--Marmich base made from it; 3--polymer produced from this Mannich base. Fro. 2. °/o Polycondensation of the Mannich base from a,oJ-dihydroxytetra-(p-ph enylene oxide) at 2104-5°C as a function of weight loss. basis of weight change during the polycondensation of the Mannich base from a,~o-dihydroxytetra-(p-phenylene oxide) at 210 _+5°C. The elemental analysis of the polymers produced b y heating of the respective Mannich bases at 210 + 5°C for 3-4 hr is given in Table 2. The infrared spectra of the polymers obtained on decomposing the Mannich base are shown in Fig. 1, curve 3. The composition can be seen to be incomplete according to the spectral data and Table 2.
Thermo-reactive polymers with poly-(p-phenylenoxide) structuro
1993
T h e % c o n v e r s i o n b y t h e p o l y c o n d e n s a t i o n , calculated f r o m t h e changes o f n i t r o g e n c o n t e n t before ( N - m o n o m e r ) a n d a f t e r ( N - p o l y m e r ) heating, is s h o w n in T a b l e 2 w i t h o u t correction for weight losses. T A B L E 2. POLYMERS PRODUCED FROM MANNICH BASES
Polycondensation efficiency, N M Np x 100, NM
% By analysis
No.
Polymer
-
% Weight loss
Carbon
-
yield, calc. [ t I f°und
%
%
I
1 2 3
From I with n = O From I with n = 1 *As 2 but addition-! al heating at 250°C From I with n = 2 From I with n = 4 From phenolic Mannich base
4 5 6
68.5 72"0
5.7 5"3
3"6 2"5 [
58.2 63"5
11-5 8"0
9'5 7.5
59.1 56.8
72'0 72"9 74"1
5.0 50 4"7
1"2
m
1"4 0.7
73.0 85.0
3.8 4.5 2"2
1.5 5.0 2"5
55.8 52-6 48"2
69'0
6"3
3"6
66"7 i
* See experimental part. t According to formula: Np-.~(CHs)sN~H --(45/14)Np=3.2 I~p. 14
F i g u r e 3 shows t h e t h e r m o m e c h a n i c a l curves of p o l y m e r s p r o d u c e d on t h e
appropriate [29] i n s t r u m e n t w i t h a c o n s t a n t stress of 0.8 k g / c m ~ a n d a t e m p e r a t u r e g r a d i e n t o f 2°C/rain. T h e results o f t h e t h e r m o g r a v i m e t r i e a n a l y s i s o b t a i n e d o n
100
50 ,. /
0
~s
- ,......x,.Y,..
j °
"
_I--
tO0
200
JO0
000
500
6'00
70077,"g
FIG. 3. Thermomechanical curves of polymers produced from I. n: •--0; 2--1; 3--2; 4--4; 5--polymer produced from phenol via the Mannich base. a t h e r m i o n i c b a l a n c e B-60 m a d e b y t h e firm " D a m " are s h o w n in Fig. 4; t h e y were o b t a i n e d b y h e a t i n g t h e s a m p l e s in a h e l i u m s t r e a m a t a c o n s t a n t r a t e o f 5°C/rain. T h e d e f o r m a t i o n c a n b e seen to be slight u p to 500°C (Fig. 3), a l t h o u g h
Y u . P. VOROB'~V et al.
1994
in the range of intense decomposition of the polymers (Fig. 4). The temperature elevation thus did not cause the polymer to change to the highly elastic state, but caused it to decompose. The crosslinking intensity changes in the selected range did not result in any marked change of the thermomechanical properties of the polymers. This could be due to the fairly high crosslinking density. The thermogravimetric curves of Fig. 4 show that the intese decomposition of the polymers started above a temperature of about 320°C. Before that the weight losses were due to decomposition of the residual amino groups present in the polymers. The data obtained from the curves was used to give the weight losses of polymers before the start of intense decomposition (320°C) in Table 2, together with those calculated from the residual N-content of the polymers and under conditions of complete decomposition of the Mannich bases. There was good agreement between the found and calculated weight losses. This indicated that the weight losses of the polymer up to about 320°C were due to further decomposition of the Mannich bases. In the temperature range 320600°C there was intense decomposition o~ all the polymers which resulted in a high yield of a carbonaceous residue. This yield is also given in Table 2 after thermal treatment of the polymers up to 900°C, taking into account the weight loss up to 320°C.
~N. .N
I
200
I
I
000
I
GO0
;
1
I
800 ~
Fro. 4. Thermogravimetric curvcs of the polymers produced from I. n: 1--0; 2--I; 3--2; 4--4; 5--I (polymer further heated at 250°C to constant weight). The results given here are evidence of an increasing poly-(p-phenylene oxide) segment length, and consequently of the lower erosslinking density in the polymer, slightly reducing the carbon yield. This change is rather small compared with the carbon yield from polymers containing polymethylene segments of different length between the :phenol rings, as found by two of the authors in eonjmmtion with Doroshenko [30]. The explanation for this could be that the compounds with a phenylene oxide structure tend towards compacting at 400-600°C rather than decomposition.
Thermo-reaetive polymers with poly-(p-phenylenoxide) structure
1995
EXPERIMENTAL Synthesis of I with n ~ 0. 3 g of the respective bis-phenol and 3.4 ml of an aqueous 37% CH~O solution were mixed at 20°C a n d 5.4 ml of a 44% aqueous dimethylamine solution were added dropwise. The precipitate was filtered off the next day, washed with water and dried. This yielded 4-2 g (89.5°/o of theory) of an impure product, which was recrystallized from ethanol and gave 2.8 g of a substance with m.p. 136-137°C. Tjhe results of analysis are listed in Table 1. " Synthetis of I with n ~ 1. 2-9 g of the respective bis-phenol was dissolved in 6-0 ml dioxane, 2.4 ml of a 37 % aqueous CH20 solution were poured to it at 20°C and then 4- 8 ml of a 44 % dimethylamine solution. This was diluted the next day with water and the forming precipitate filtered off, washed and dried. This yielded 4.0 g (98.0% of theory) of a product which was recrystallized from acetone. The final product weighed 1.8 g; m.p. 182-184°C. Its analysis is given in Table 1. Synthesis of I with n ~ 2. This was produced from 1-3 g of the respective bis-phenol, 6.0 ml dioxane and 0.8 ml of 37% aqueous CH~O solution b y mixing at 20°C. To the solution were added 2.0 ml of a 3 6 . 0 % dimethylamine solution, the whole was left to stand for 2 days and the resulting oil was separated with water. Decanting of the water left a tarry product which was dissolved in acetone, the solution was treated with carbon, the acetone boiled off, and the product then vacuum-dried. The yield was 1.3 g (74-0% of theory) of a resinous yellow mass. An a t t e m p t to recrystallize this failed. The analytical result is given in Table 1. Synthesis of I with n ~ 4 . 0.9 g of the bis-phenol was dissolved in 50 ml dioxane, 1 ml of an aqueous 37~o Ctt20 solution and of a 44% dimethylamine solution were adeed. The reaction progress was controlled b y analysis of the product for nitrogen. The reaction mass was kept at 20°C for one m o n t h and contained 3 . 3 % nitrogen (calculated content., N ~ 4 . 1 % ) . Another 0-5 ml of the reagents was added,' the solvent evaporated after 10 days standing under v a c u u m at 20°C and the product dried. This yielded 1.0 g (84.0% of theory) of a substance whose analysis is given in Table 1. Production of phenolic Mannich base. The procedure was that described for 2,4,6-tris(dimethylaminomethyl)-phenol [14]; 18.8 g phenol and 26.8 g 37% Ctt20 were mixed and 54.5 g of 44% dimethylamine solution were added dropwise so t h a t the temperature did not exceed 25°C. The reaction mixture was then heated for 1 hr on a steam bath and the oil formed was separated. Vacuum-drying yielded 22.0 g (60.0% of theory) e r a yellow oil; the analytical results can be found in Table l. Polycondensation of Mannich bases. This was carried out b y heating in a condenser test tube under a slow helium stream at 210~5°C to constant weight. One of the polymers (from I with n : 1) was further heated to 250°C until its weight became constant.
CONCLUSIONS (1) T h e r m o - r e a c t i v e p o l y m e r s w i t h d i f f e r e n t c r o s s l i n k i n g d e n s i t i e s w e r e p r o d u c e d f r o m 4 , 4 - d i h y d r o x y d i p h e n y l oxide, ~ , o J - d i h y d r o x y - t r i - , t e t r a - , a n d h e x a ( p - p h e n y l e n e oxide) a n d formaldehyde. (2) C h a n g e s o f t h e c r o s s l i n k i n g d e n s i t y i n t h e s y n t h e s i z e d p o l y m e r s d i d n o t result in a n y s u b s t a n t i a l changes of their t h e r m o m e c h a n i c a l properties a n d thermal stability.
Translated by K . A . ALLEN
1996
Yu. P. VOROB'EV et aL REFERENCES
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