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Aromatic polyamides containing cyclic groups in the side chain
AROMATIC POLYAMIDES CONTAINING CYCLIC GROUPS IN THE SIDE CHAIN* S. N. ](~AR'XOV, L. P. GRECHUSHNIKOVA,A. S. CHEGOLYA,YE. P. KRAS~OV, K. K. PR~.OB~AZ~S~, R. N. Gamov and yr.. A. VOROB'~V All-Union Synthetic Fibres Research Institute
(Received 21 Augu~ 1970) THE aromatic polyamides (PA) have good thermal and physicomechanical properties [1, 2], but the majority are non-melting and almost insoluble products, so that their processing is rather di~cult (fibres, films, surface coatings etc.), and sometimes even impossible. The limited solubility is also a serious obstacle to the production of polymers with a large molecular weight (mol.wt.). The recently synthesized aromatic PA with bulky substituents in the side chain (branch) [3, 4] are of great interest since they have high heat resistance and are quite soluble in numerous organic solvents. This work describes the systematic study of the effects of chemical structure of the branch on the properties of the aromatic PA, such as the heat resistance and thermal stability, the structure, mol.wt, distribution (MWI)), the stability of concentrates, and the fibre-forming capacity. Thermal lyro~erffes. The polymers were produced by polycondensation in solution and the main principles of the synthesis were described in earlier reports [3, 4]. Table 1 lists the thermal properties of the polyterephthalamides (PTPA) produced by low temperature polycondensation in dimethyl acetamide (DMA). We also produced in the same manner aromatic PA without cyclic groups in the branch, so as to have controls for comparison purposes. Table 1 shows that the PA containing phenyl rings connected with each other by an amide bond have the best thermal properties, i.e. the PTPA based on benzidine. Insertion of methylene groups into the polymer chain, and particularly bulky side groups, greatly reduced the thermal properties, and the nature of the group was of great importance. The least thermostable, particularly in air, were polymers with methylene groups in the polymer chain (PA l-I, III, VIII); this seems to be caused by an air oxidation of these groups. The fact that heating these polymers in air produced an exothermic peak at 350-355°C on the DTA curve, and a large weight increase evident on the TGA curve, confirmed this statement. The PA with an anthrone (VII) or fluorene (VI) substituent, in contrast, had much higher decomposition temperatures in air and in vacuum. In* Vysokomol. soyed. AI4: No. 4, 817-824, 1972.
910
Aromatic poly~m~des containing cyclic groups T~
Polymer
1. Ts~ ~ A T ,
PROrEB~S Or PTPA State of phase*
Main chain umt
I 0
0
II 0
III \=/ J
Start of deComposition, ° C
Softenmg pomt, oC
in air
vacuum
v.c.
>480
470
500
c
>480
410
435
p.o.
305
340
395
a
285
400
405
a
360
430
400
a
400
440
400
p.c.
420
460
420
a
410
390
4O0
in
O
II \-~-/ 11 0
911
0
IV I
,
o
©
o
V 0 =°
VI
VII
0
VIII
* v.o.--very crystalline; p.c.--partly crystalline, a--amorphous; c--crystalline.
terestingly t h e s e p o l y m e r s were m o r e stable in air t h a n in a v a c u u m . T h e c o m p a r i s o n o f t h e properties o f P A I V a n d V, which differ b y t h e polar lactone g r o u p p r e s e n t in P A V, showed t h a t t h e p o l a r i t y o f t h e s u b s t i t u e n t did n o t noticeable affect t h e t h e r m a l stability o f t h e p o l y m e r , b u t strongly affected its h e a t resistance. T h e presence o f t h e laetone g r o u p raised t h e softening p o i n t o f P A V b y 75°C a b o v e t h a t o f P A IV, which does n o t seem to be due only to t h e p~larity o f this group, b u t also t o a rigidity increase o f t h e macromolecule d u e t o One o f t h e C-atoms o f t h e lactone ring entering t h e m a i n p o l y m e r chain, a n d t h u s hindering t h e p h e n y l ring r o t a t i o n a r o u n d t h e C - - C bond.
912
S, N. KHAR'KOV et a~.
Solubilities. The results of studying the solubilities of the aromatic PA produced by low-bemperature polycondensation in DMA are given in Table 2. It shows that insertion of cyclic groups into the polymer chain greatly improved the solubility in various solvents. The actual structure of the substituent and its polarity did not play an important part. The exception was here PA VIII, which has dihydro-anthracene substituents; these were insoluble in all of the solvents listed, which differed from the behaviour of other PA with bulky substituents. The reason appears to be the high reactivity of the methylene group present in the dihydroanthracene ring; it reacted with the terephthaloyl chloride during synthesis and gave rise to a "crosslinked" polymer:
C
E/~c=_o H
0
\/
C~O
C
/I
This possibility was studied on the anthrone-9 reaction with benzoyl- and benzyl chlorides in DMA at --5°C as model. We found that acylation of the methylene group of anthrone to 10-benzoyl- and 10-benzyl-9-anthrone took place: O
H/\~
O
H/\C__O
0
Aromatic polyamides containing cyclic groups
913
The non-polar PA IV was more soluble t h a n the polar PA V and this seems to have been due to the greater rigidity and greater molecular interactions in the latter case. A more noticeable effect of the group structure present in the branch TABLE 2. THE PTPA SOLUBILITIES Solvent? Polymer
[ 0 ] ~ H=SO~ DMP
I
o.o +
III
IV v
VI vii VIII
DMF + 5% LiCI
DMA
1-58 1.60
+
+
+
+
+
+
2.08
+
+
+
+
1.20
+
+
+
0.95
+
+
+
MP
I
DMSO
AP
Cyclohexanone
i=
+
+
+
+
+
+
+
+
+
+
+
+
heated )
* The visecetty was determined at 25°C on 0"5% polymer solutions in DMF contatnt~ 5% LtCl (II--l~ H=SO,, VII--in DMF not containing the salt). ? DMF--~lmethyl formamide, DMA--dimethyl acetamide, MP--methyil~yrrolidone, DMBO~dlmethyl sutphoxide, AP~N-aoyl plperldine, + ~ d i n o l v e s , ----not Boluble.
was found in the stabilities of PA concentrates. Viscosity studies (ball method) on 15% polymer solutions in organic solvents showed those of PA I I I and VI remained stable for a month when stored in all the solvents at 20°C, while PA IV and VII became unstable in some of the solvents (Fig. 1).
30O
~ ~
zoof 100
.
T~
+ q
°
:-:
A
fl
i 8
3oor
u J
,
I T + + 12 [6
^
i
A
2
350
7
-._%-1
,=~ - i Z o o ~ . ~
20
20
2
6
i
10
"+
~ "= I/4
~
i ' :~ i
+'1
[8
Time , daus
FxG. 1. The stabd]ty of 15% solutions of: a---polymer IV, b---polymer VII, m organic solvents at 20°C: 1--DM_F, 2--DMA, 3--DMS, 4--1KP, 5--DMF+5% LiC1, 6--AP. The behaviour of PA VII was of some interest since it precipitated Dut of D]KF and DMA solutions when lithium chloride was added. A mineral salt addition, especially of IAC1, is known to improve the solubility of PA in amide solvents. One can assume this precipitation to be associated with a phase transitionlof the polymer, or with an aggregation of the macromolecules in the presence ~f the inorganic salt. The structural s t u d y of the PA VI precipitating out of I)MA solu-
914
S. N . K H ~ a ' x o v e$ a/.
tions on adding water or LiC1 was carried out by X-ray analysis and by infrared spectroscopy; this did not disclose any differences, nor did the solubility study. The densities of such samples, however, showed quite significant differences (1.3997 compared with 1.3673 of the precipitate), so that macromolecular aggregation in the presence of LiC1 due to the reaction of the carbonyl group of the anthrone substituent with the lithium ion was more probable here than in the case of PA I, II, and V. Effect of the synthetic method on the properties of PA. The production methods, in addition to the chemical structure, had a substantial effect on the properties of rigid-chain polymers [4, 6, 7]; we therefore studied the effects of synthesis on the solubility, structure and MWD of the PA containing bulky substituents. In addition to the low-temperature polycondensation in amide solvents the polymers were also synthesized by interface polycondensation using cyclohexanone, dioxane, tetrahydrofuran (THF) or chloroform as the organic phase. The viscosity of the polymers obtained as a result of the latter process was usually only 0-3 to 0.5 of that of the low temperature polycondensation in DMA or MP. The X-ray structural analysis of the PA showed polybenzidine terephthalamide to have the highest ~/o crystallinity. Insertion of methylene, and especially of cyclic groupings, into the branch between the phenyl rings, strongly inhibited crystallization, but did not eliminate it. PA IV, V and VI were found to have an amorphous structure regardless of the synthetic method used. In contrast to these, PA II and VII contained a considerable amount of crystalline phase, which depended on the synthetic method. Their MWD was also affected by it. Other work [7] had shown the polymetaphenylene isophthalamide produced by polycondensation in solution to differ from that produced in an emulsion process by having a smaller content of the low mol.wt, fractions (3-7, instead of 13-17%), and no fraction with a very large mol.wt.; its polydispersity was also smaller. The PA H I and IV were used here to study the effect of the synthetic method on their MWD. The polymers were fractionally-precipitated and the fractions separated between two liquid phases as described elsewhere [7]. The solvent was DMF with a 5% LiC1 content and the precipitant dioxane. These polymer samples were produced by a solution polycondensation in DMA and by an emulsion polycondensation in THF as organic phase; they were fractionally-precipitated into 15-20 fractions. The mol.wt, of the latter were calculated from their intrinsic viscosities. The experimental results were processed by the l~Iark and Raft method
[8]. The MWD curves for PA I I I synthesized by the mentioned 2 methods are reproduced in Fig. 2; they can be seen to be very broad. Both the curves have the same bimodal appearance, but show distinct differences. The peak on the differential MWD curve of the sample produced by the emulsion process is displaced towards smaller mol.wt., which doubtlessly will mean poorer fibre-drawing properties of this polymer. This polymer was fairly non-homogeneous and contained up to 1 0 ~ of low mol.wt, fraction, while the polymer produced by the solution
Aromatic polyamides containing cyclic groups
915
process did not contain more than 3 - 4 ~ . The polydispersity of the latter, calculated by the Schulz method, was smaller (0.76) than by the emulsion p~ocess (1-34). Similar results were obtained in an M W I ) s t u d y with polytriphenylmCthane terephthalamide. The polycondensation in solution thus ensured a greater uniforrnity of MWD. The good solubilities of the P A having bulky substituents and the stability of their concentrates made it possible to process them into various articles (semi~products). The fibredirawing study showed them all to be suitable for processing directly from their syrups.
AVV'IAf~3
_- F'~
550
r~ z~50 -
,o f
350-
250 -
150 -
J I 0
0.0
I
0"8
I
I
I'2 ~['2]
I
I
I
I'6
I
2"0 IFIG. 3
FIG. 2
FIG. 2. The MWI) curves of PA HI synthesized by emulsion polycondensation (1), and solution polycondensation in DMA (2). FIG. 3. The mechanical strength retention of fibres at elevated temperature (P-{-phenylone; the numerals alongside the curves are the polymer numbers cited in Table 1). The presence of bulky substituents in the branches of the polymer chains made orientation and crystallization di~cult, so that high-strength fibres could not be produced. The fibres produced b y the wet method thus had a strength of only 30 rkm. Although amorphous, t h e y were highly heat-resistant and some of them were in this respect superior to heat-resistant, crystalline phenylone (V, VI, VII), as Fig. 3 shows. EXPERIMENTAL
~£ronomer ~ . The dzamlrtes (w~h the exception of VIII) were produced by condensing aniline with the respective aldehydes or ketones tn the presence of acid catalysts. The compounds had the following properties after vacuum-chstillatlon or reerystallizatlon: 1,1-bis-4-aminophenylcyclohexane, m.p. 117-119°C (lll°C according to data m r~f. [9]). \
916
S. N . w w * R ' x o v
e~ a/.
4,4'-I)mmmotrlpheny]methane, m.p. 135-136°C (139°C according to ref. [10]). 3,3-Bm-4. aminophenyl phthalide, m.p. 202-203°C (204°C according to ref. [11]). 9,9-Bis-4-aminophenyl fiuorene, m.p. 234-236°C (233°C according to ref. [12]). 9,9-Bis-4-aminophenyl-10-anthrone, m.p. 302-304°C (298°C according to ref. [13]).
Yk ., ~.,,.a
~ ["
0
E
i.'
~i.I •
.w
.
II
i
"~<~50
"
- L-
"
',v'"
I
1DOL 100 " J6
i
t 3~
i
I 32
I
I 30
Z I i ~
t
i Z8
~
t,
18
~
I I il
''"
';""
I I|lll I i I1~
II
I~l ~1 I I t 16 114 12
I
A I0
I
I
~', I0 "2, crn -I
Fig. 4. The infrared spectra of: /--9,9-bis-4-ammophenyl dlhydroanthracene, 2--9,9-bls-4aminophenyl anthrone, 3--9-anildlhydroanthracene.
Unexpectedly, the aniline condensatzon with anthrone ymlded, instead of the 9,9-bls-4aminophenyl-dihydroanthracene, a compound which according to the physmal constants, infrared spectroscopy, and elemental analysis, was the 9-anildihydroanthracene, m.p. 206-208°C (203°C according to ref. [14]). The results of elemental analyms were Found, %: C~0H16N. Calculated, %:
89.86, 89.62 C; 5.50, 5.56 H; 4.95, 4-90N. 89.23 5.57 5-20
The 9,9-bis-4-ammopheny] dihydroanthracene, not described so far m the literature, was therefore produced b y the Clemensen reduction [15] of 9,9-bis-4-aminophenyl-10anthrone as follows. A mixture of 100 g zinc powder, 7 g mercurous chloride, 5 ml conc. HC1 and 130 m] water was energetically st~rred 10 ram. The aqueous solution was then decanted and to the remanung zinc alloy were added 175 ml of HC1 diluted 1 : 1, after which a 40 g suspension of the 9,9-bis-4-an~nophenyl-10-anthronem 200 ml dioxane was gradually added over 30 rain. The mass was smamered for 12 hr and during thin t n n e were gradually added 400 ml conc. HCI. The zinc amalgamate was filtered off, washed with dioxane, a n d the filtrate poured, while energetically stirred, rote a 1 : 4 aqueous ammonia solution. Impurltms were removed from the resulting white sediment b y filtration and washing with water, then dissolving the dmmme m 150 m] I)M.A to remove morgamc salts, prempltating with water a n d recrystalllzmg from aqueous acetone. Drying yielded 26 g (68%) of a white powder with m.p. 245-248°C. The results of elemental analysis were l~ound, %:
C26HtsNt. Calculated, %:
86.26, 86.20 C; 6.31, 6.22 H; 8.13, 8.07 N. 86.19 6.07 7.77
The infrared spectra of the 9,9-bis-4-aminophenyl-10-anthrone, 9,9-bis-4-A~nlnophenyl dihydroanthracene and 9-anildihydro anthracene are reproduced in Fig. 4.
Aromatic polyaa'nides containing cyclic groups
917
The polymera were ~ a t h e ~ z e d by low-temperature polycondensation m solution and by interface polycondensatlon by the well-known method, which had been described in detail before [4]. The polymer8 were fraet/onate~ by distrlbutzon between two hqmd phases as follows: 5 g of polymer were dissolved m DMF containing 5°//oLzC1;the 16~/o solution was then diluted to 1.5% concentration by adding a DM:F/dioxane rmxture of 40 : 60 ratio by weighti m the case of polymer III, and 75 : 25 of polymer IV. To this dilute solutzon maintained at 25oc was added dioxane m a series of drops, while mixing, until a stable turbzdity appeared. The solution was then set aside for severalhours and the gel-like polymer precipitate sel~rated from the solution by decanting; the precipitate was recovered as thin Alms by precipitation wath water, or as a powder. The transparent dilute solution was transferred to another beaker, another ahquot portzon of dioxane was added, and the next polymer fraction was separated. The molecular weight distribution curves (MW])) were plotted from the intrinsm vzscomtms determined in a suspended-level Ubbelohde viseemeter (0.54 mm dia. ealJillary). The solvent was DMI~ containing 5% LiC1. The X - r a y st~.uc~ural analysis of the polymer was made with the URS-60 instnunent, usn~ a plate camera and CuK~ radiation filtered through a nickel filter. Cold-pressed tablets were used as samples. The heat resistance in a vacuum was determined from the gas liberation by the method described m another communication [16]. That in air was determined by thermogra~hnetry in a derlvatograph. The temperature gradient was 5°C/min. The thermomechanical curves were recorded on the instrument described by Gerasimov and others [17]; the temperature gradient was here 2°C]min and the load 3 kg/cm z.
CONCLUSIONS (1) Solution a n d interface p o l y c o n d e n s a t i o n s were used t o p r o d u c e a r o m a t i c p o l y a m i d e s containing phenyl, cyclohexyl, phthalide, a n t h r o n e a n d d i h y d r o a n t h r a c e n e groups in t h e branch. (2) T h e influence o f t h e chemical s t r u c t u r e a n d o f t h e synthesis m e t h o d s a n d t h e solubility, ,;,racture, h e a t resistance a n d t h e r m a l stability, M W D a n d o t h e r properties, was studied on p o l y t e r e p h t h a l a m i d e s w i t h b u l k y s u b s t i t u e n t s i n t h e branches. Translated by K. A. A L I ~
REFERENCES 1. R. A. DINE-HART, B. L MOORE and W. W. WRIGHT, J. Polymer Sci. B$: 3~9, 1964 2. Ye. P. KRASN0V, V.M. SAVINOV, L. B. SOKOLOV, V. I. LOGUNOVA, T. A. POLYAKOVA, and V. K. BELYAK0V, Vysokomol. soyed. 8: 380, 1966 (Translated in Polymer Sci. U.S.S.R. 8: 3, 413, 1966) 3. S. V. VINOGRADOVA, V. V. KORSHAK, Ya. S. VYGODSKH and V.I. ZAITSEV, Vysokotool. soyed. Ag: 653, 658, 1967 (Translated in Polymer Sei. U.S.S.R. 9: 3, 731, 11967) 4. S. N. KHAR'KOV, A. S. CHEGOLYA, Ye. P. KRASNOV, L. P. GRECHUSHNEKOVA, G. A. KURAKOV and V. A. PANTAYEV, Vysokomol. soyed. A l l : 2053, 1969 (Translated m Polymer Sci. U.S.S.R. 11: 9, 2353, 1969) 5. U. S. Pat. No. 3068188, 1957 6. V. M. SAVINOV, G. A. KUZNETSOV, V. D. GERASIMOV and L. R. SO]KOLOV,Vysokotool. soyed. Bg: 590, 1967 (Not translated in Polymer Sci. U.S.S.R.) 7. R. N. GRIBOV, V. A. MYAGKOV and I. F. DEVNINA, Sintetmheskie volokn~ (Synthetm Fzbres). p 66, Izd. "Khuniya", 1969
I. N. TOPCHIEVAe$ a/.
918
8. s. R. RAFIKOV, S. A. PAVLOVAand I. I. TV]gRDO~HI.E~OVA, Metody opredeleniya molekulyarnykh vesov i poludispersnosti vysokomolekulyarnykhsoyedinenii (Molecular Weight and Polydisperslty Determination Methods for High Polymers). p. 64, Izd. Akad. Nauk SSSR, 1963 9. German Pat. No. 497628, 1928 10. H. WEIL, E. SAPPER, E. KR:d~MER,K. KL~TER and H. SELBERG, Ber. 61: 1299, 1928 11. G. SCHWARZENBACHand M. BRANDERBERGER, Helv. China. Acta $0: 1253, 1937 12. British Pat. No. 467824, 1935 13. German Pat. No. 488612, 1926 14. C. PADOVA, Comtp. rend. 149: 218, 1909 15. R. ADAMS (Ed.), Organic Reactions, vol. 1, Izd. mostr, hr., p. 203, 1948 (Russian translation) 16. Ye. P. KRASNOV and L. B. SOKOLOV, Sb.: Khimicheskie svoistva 1 modifilcatsiya polimerov (In: The Chemical Properties and Modifications of Polymers). p. 275, Izd. "Nauka", 1964 17. V. D. GERASIMOV, G. A. KUZNETSOV and L. N. FOMENKO, Zavod. labor. 29: 256, 1963
THE
POLYOXYETHYLENE E T H E R OF NoBENZOYLHISTIDINE AS A MODEL OF ALLOSTERIC E N Z Y M E ASSOCIATION*
I. N. TOPCHIEVA, A. B. SOLOV'EVA, B. I. KURGA~OV and V. A. KABANOV M. V. Lomonosov State University, Moscow
(Received 21 July 1970) THE temperature dependence of the 1~-nitrophenyl acetate (NPA) hydrolysis rate, catalysed by the polyoxyethylene ether of the N-benzoylhistidine (POBH), was investigated [1]. An important finding was the detection of sensitivity to the eonformational changes and chemical properties of the polymeric catalyst (PC), which took place when the temperature changed. These changes were associated with changes in the contribution by non-polar (hydrophobic) reactions to the stabilization of one or the other conformation. J u s t as interesting was the s t u d y of the effect of the p H of medium, the substrate, the reaction product, and of various other substances, on the conformational state of PC, and therefore its catalytic activity (efficiency). The aim of the work reported here was the study of conformation transitions in POBH, which took place as a result of the p H changes in the presence of NPA and the reaction product, p-nitrophenol (NP), which led to catalytic property changes of PC. * Vysokomol. soyed. AI4: No. 4, 825-837, 1972.
(Received 21 Augu~ 1970) THE aromatic polyamides (PA) have good thermal and physicomechanical properties [1, 2], but the majority are non-melting and almost insoluble products, so that their processing is rather di~cult (fibres, films, surface coatings etc.), and sometimes even impossible. The limited solubility is also a serious obstacle to the production of polymers with a large molecular weight (mol.wt.). The recently synthesized aromatic PA with bulky substituents in the side chain (branch) [3, 4] are of great interest since they have high heat resistance and are quite soluble in numerous organic solvents. This work describes the systematic study of the effects of chemical structure of the branch on the properties of the aromatic PA, such as the heat resistance and thermal stability, the structure, mol.wt, distribution (MWI)), the stability of concentrates, and the fibre-forming capacity. Thermal lyro~erffes. The polymers were produced by polycondensation in solution and the main principles of the synthesis were described in earlier reports [3, 4]. Table 1 lists the thermal properties of the polyterephthalamides (PTPA) produced by low temperature polycondensation in dimethyl acetamide (DMA). We also produced in the same manner aromatic PA without cyclic groups in the branch, so as to have controls for comparison purposes. Table 1 shows that the PA containing phenyl rings connected with each other by an amide bond have the best thermal properties, i.e. the PTPA based on benzidine. Insertion of methylene groups into the polymer chain, and particularly bulky side groups, greatly reduced the thermal properties, and the nature of the group was of great importance. The least thermostable, particularly in air, were polymers with methylene groups in the polymer chain (PA l-I, III, VIII); this seems to be caused by an air oxidation of these groups. The fact that heating these polymers in air produced an exothermic peak at 350-355°C on the DTA curve, and a large weight increase evident on the TGA curve, confirmed this statement. The PA with an anthrone (VII) or fluorene (VI) substituent, in contrast, had much higher decomposition temperatures in air and in vacuum. In* Vysokomol. soyed. AI4: No. 4, 817-824, 1972.
910
Aromatic poly~m~des containing cyclic groups T~
Polymer
1. Ts~ ~ A T ,
PROrEB~S Or PTPA State of phase*
Main chain umt
I 0
0
II 0
III \=/ J
Start of deComposition, ° C
Softenmg pomt, oC
in air
vacuum
v.c.
>480
470
500
c
>480
410
435
p.o.
305
340
395
a
285
400
405
a
360
430
400
a
400
440
400
p.c.
420
460
420
a
410
390
4O0
in
O
II \-~-/ 11 0
911
0
IV I
,
o
©
o
V 0 =°
VI
VII
0
VIII
* v.o.--very crystalline; p.c.--partly crystalline, a--amorphous; c--crystalline.
terestingly t h e s e p o l y m e r s were m o r e stable in air t h a n in a v a c u u m . T h e c o m p a r i s o n o f t h e properties o f P A I V a n d V, which differ b y t h e polar lactone g r o u p p r e s e n t in P A V, showed t h a t t h e p o l a r i t y o f t h e s u b s t i t u e n t did n o t noticeable affect t h e t h e r m a l stability o f t h e p o l y m e r , b u t strongly affected its h e a t resistance. T h e presence o f t h e laetone g r o u p raised t h e softening p o i n t o f P A V b y 75°C a b o v e t h a t o f P A IV, which does n o t seem to be due only to t h e p~larity o f this group, b u t also t o a rigidity increase o f t h e macromolecule d u e t o One o f t h e C-atoms o f t h e lactone ring entering t h e m a i n p o l y m e r chain, a n d t h u s hindering t h e p h e n y l ring r o t a t i o n a r o u n d t h e C - - C bond.
912
S, N. KHAR'KOV et a~.
Solubilities. The results of studying the solubilities of the aromatic PA produced by low-bemperature polycondensation in DMA are given in Table 2. It shows that insertion of cyclic groups into the polymer chain greatly improved the solubility in various solvents. The actual structure of the substituent and its polarity did not play an important part. The exception was here PA VIII, which has dihydro-anthracene substituents; these were insoluble in all of the solvents listed, which differed from the behaviour of other PA with bulky substituents. The reason appears to be the high reactivity of the methylene group present in the dihydroanthracene ring; it reacted with the terephthaloyl chloride during synthesis and gave rise to a "crosslinked" polymer:
C
E/~c=_o H
0
\/
C~O
C
/I
This possibility was studied on the anthrone-9 reaction with benzoyl- and benzyl chlorides in DMA at --5°C as model. We found that acylation of the methylene group of anthrone to 10-benzoyl- and 10-benzyl-9-anthrone took place: O
H/\~
O
H/\C__O
0
Aromatic polyamides containing cyclic groups
913
The non-polar PA IV was more soluble t h a n the polar PA V and this seems to have been due to the greater rigidity and greater molecular interactions in the latter case. A more noticeable effect of the group structure present in the branch TABLE 2. THE PTPA SOLUBILITIES Solvent? Polymer
[ 0 ] ~ H=SO~ DMP
I
o.o +
III
IV v
VI vii VIII
DMF + 5% LiCI
DMA
1-58 1.60
+
+
+
+
+
+
2.08
+
+
+
+
1.20
+
+
+
0.95
+
+
+
MP
I
DMSO
AP
Cyclohexanone
i=
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* The visecetty was determined at 25°C on 0"5% polymer solutions in DMF contatnt~ 5% LtCl (II--l~ H=SO,, VII--in DMF not containing the salt). ? DMF--~lmethyl formamide, DMA--dimethyl acetamide, MP--methyil~yrrolidone, DMBO~dlmethyl sutphoxide, AP~N-aoyl plperldine, + ~ d i n o l v e s , ----not Boluble.
was found in the stabilities of PA concentrates. Viscosity studies (ball method) on 15% polymer solutions in organic solvents showed those of PA I I I and VI remained stable for a month when stored in all the solvents at 20°C, while PA IV and VII became unstable in some of the solvents (Fig. 1).
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FxG. 1. The stabd]ty of 15% solutions of: a---polymer IV, b---polymer VII, m organic solvents at 20°C: 1--DM_F, 2--DMA, 3--DMS, 4--1KP, 5--DMF+5% LiC1, 6--AP. The behaviour of PA VII was of some interest since it precipitated Dut of D]KF and DMA solutions when lithium chloride was added. A mineral salt addition, especially of IAC1, is known to improve the solubility of PA in amide solvents. One can assume this precipitation to be associated with a phase transitionlof the polymer, or with an aggregation of the macromolecules in the presence ~f the inorganic salt. The structural s t u d y of the PA VI precipitating out of I)MA solu-
914
S. N . K H ~ a ' x o v e$ a/.
tions on adding water or LiC1 was carried out by X-ray analysis and by infrared spectroscopy; this did not disclose any differences, nor did the solubility study. The densities of such samples, however, showed quite significant differences (1.3997 compared with 1.3673 of the precipitate), so that macromolecular aggregation in the presence of LiC1 due to the reaction of the carbonyl group of the anthrone substituent with the lithium ion was more probable here than in the case of PA I, II, and V. Effect of the synthetic method on the properties of PA. The production methods, in addition to the chemical structure, had a substantial effect on the properties of rigid-chain polymers [4, 6, 7]; we therefore studied the effects of synthesis on the solubility, structure and MWD of the PA containing bulky substituents. In addition to the low-temperature polycondensation in amide solvents the polymers were also synthesized by interface polycondensation using cyclohexanone, dioxane, tetrahydrofuran (THF) or chloroform as the organic phase. The viscosity of the polymers obtained as a result of the latter process was usually only 0-3 to 0.5 of that of the low temperature polycondensation in DMA or MP. The X-ray structural analysis of the PA showed polybenzidine terephthalamide to have the highest ~/o crystallinity. Insertion of methylene, and especially of cyclic groupings, into the branch between the phenyl rings, strongly inhibited crystallization, but did not eliminate it. PA IV, V and VI were found to have an amorphous structure regardless of the synthetic method used. In contrast to these, PA II and VII contained a considerable amount of crystalline phase, which depended on the synthetic method. Their MWD was also affected by it. Other work [7] had shown the polymetaphenylene isophthalamide produced by polycondensation in solution to differ from that produced in an emulsion process by having a smaller content of the low mol.wt, fractions (3-7, instead of 13-17%), and no fraction with a very large mol.wt.; its polydispersity was also smaller. The PA H I and IV were used here to study the effect of the synthetic method on their MWD. The polymers were fractionally-precipitated and the fractions separated between two liquid phases as described elsewhere [7]. The solvent was DMF with a 5% LiC1 content and the precipitant dioxane. These polymer samples were produced by a solution polycondensation in DMA and by an emulsion polycondensation in THF as organic phase; they were fractionally-precipitated into 15-20 fractions. The mol.wt, of the latter were calculated from their intrinsic viscosities. The experimental results were processed by the l~Iark and Raft method
[8]. The MWD curves for PA I I I synthesized by the mentioned 2 methods are reproduced in Fig. 2; they can be seen to be very broad. Both the curves have the same bimodal appearance, but show distinct differences. The peak on the differential MWD curve of the sample produced by the emulsion process is displaced towards smaller mol.wt., which doubtlessly will mean poorer fibre-drawing properties of this polymer. This polymer was fairly non-homogeneous and contained up to 1 0 ~ of low mol.wt, fraction, while the polymer produced by the solution
Aromatic polyamides containing cyclic groups
915
process did not contain more than 3 - 4 ~ . The polydispersity of the latter, calculated by the Schulz method, was smaller (0.76) than by the emulsion p~ocess (1-34). Similar results were obtained in an M W I ) s t u d y with polytriphenylmCthane terephthalamide. The polycondensation in solution thus ensured a greater uniforrnity of MWD. The good solubilities of the P A having bulky substituents and the stability of their concentrates made it possible to process them into various articles (semi~products). The fibredirawing study showed them all to be suitable for processing directly from their syrups.
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FIG. 2. The MWI) curves of PA HI synthesized by emulsion polycondensation (1), and solution polycondensation in DMA (2). FIG. 3. The mechanical strength retention of fibres at elevated temperature (P-{-phenylone; the numerals alongside the curves are the polymer numbers cited in Table 1). The presence of bulky substituents in the branches of the polymer chains made orientation and crystallization di~cult, so that high-strength fibres could not be produced. The fibres produced b y the wet method thus had a strength of only 30 rkm. Although amorphous, t h e y were highly heat-resistant and some of them were in this respect superior to heat-resistant, crystalline phenylone (V, VI, VII), as Fig. 3 shows. EXPERIMENTAL
~£ronomer ~ . The dzamlrtes (w~h the exception of VIII) were produced by condensing aniline with the respective aldehydes or ketones tn the presence of acid catalysts. The compounds had the following properties after vacuum-chstillatlon or reerystallizatlon: 1,1-bis-4-aminophenylcyclohexane, m.p. 117-119°C (lll°C according to data m r~f. [9]). \
916
S. N . w w * R ' x o v
e~ a/.
4,4'-I)mmmotrlpheny]methane, m.p. 135-136°C (139°C according to ref. [10]). 3,3-Bm-4. aminophenyl phthalide, m.p. 202-203°C (204°C according to ref. [11]). 9,9-Bis-4-aminophenyl fiuorene, m.p. 234-236°C (233°C according to ref. [12]). 9,9-Bis-4-aminophenyl-10-anthrone, m.p. 302-304°C (298°C according to ref. [13]).
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Fig. 4. The infrared spectra of: /--9,9-bis-4-ammophenyl dlhydroanthracene, 2--9,9-bls-4aminophenyl anthrone, 3--9-anildlhydroanthracene.
Unexpectedly, the aniline condensatzon with anthrone ymlded, instead of the 9,9-bls-4aminophenyl-dihydroanthracene, a compound which according to the physmal constants, infrared spectroscopy, and elemental analysis, was the 9-anildihydroanthracene, m.p. 206-208°C (203°C according to ref. [14]). The results of elemental analyms were Found, %: C~0H16N. Calculated, %:
89.86, 89.62 C; 5.50, 5.56 H; 4.95, 4-90N. 89.23 5.57 5-20
The 9,9-bis-4-ammopheny] dihydroanthracene, not described so far m the literature, was therefore produced b y the Clemensen reduction [15] of 9,9-bis-4-aminophenyl-10anthrone as follows. A mixture of 100 g zinc powder, 7 g mercurous chloride, 5 ml conc. HC1 and 130 m] water was energetically st~rred 10 ram. The aqueous solution was then decanted and to the remanung zinc alloy were added 175 ml of HC1 diluted 1 : 1, after which a 40 g suspension of the 9,9-bis-4-an~nophenyl-10-anthronem 200 ml dioxane was gradually added over 30 rain. The mass was smamered for 12 hr and during thin t n n e were gradually added 400 ml conc. HCI. The zinc amalgamate was filtered off, washed with dioxane, a n d the filtrate poured, while energetically stirred, rote a 1 : 4 aqueous ammonia solution. Impurltms were removed from the resulting white sediment b y filtration and washing with water, then dissolving the dmmme m 150 m] I)M.A to remove morgamc salts, prempltating with water a n d recrystalllzmg from aqueous acetone. Drying yielded 26 g (68%) of a white powder with m.p. 245-248°C. The results of elemental analysis were l~ound, %:
C26HtsNt. Calculated, %:
86.26, 86.20 C; 6.31, 6.22 H; 8.13, 8.07 N. 86.19 6.07 7.77
The infrared spectra of the 9,9-bis-4-aminophenyl-10-anthrone, 9,9-bis-4-A~nlnophenyl dihydroanthracene and 9-anildihydro anthracene are reproduced in Fig. 4.
Aromatic polyaa'nides containing cyclic groups
917
The polymera were ~ a t h e ~ z e d by low-temperature polycondensation m solution and by interface polycondensatlon by the well-known method, which had been described in detail before [4]. The polymer8 were fraet/onate~ by distrlbutzon between two hqmd phases as follows: 5 g of polymer were dissolved m DMF containing 5°//oLzC1;the 16~/o solution was then diluted to 1.5% concentration by adding a DM:F/dioxane rmxture of 40 : 60 ratio by weighti m the case of polymer III, and 75 : 25 of polymer IV. To this dilute solutzon maintained at 25oc was added dioxane m a series of drops, while mixing, until a stable turbzdity appeared. The solution was then set aside for severalhours and the gel-like polymer precipitate sel~rated from the solution by decanting; the precipitate was recovered as thin Alms by precipitation wath water, or as a powder. The transparent dilute solution was transferred to another beaker, another ahquot portzon of dioxane was added, and the next polymer fraction was separated. The molecular weight distribution curves (MW])) were plotted from the intrinsm vzscomtms determined in a suspended-level Ubbelohde viseemeter (0.54 mm dia. ealJillary). The solvent was DMI~ containing 5% LiC1. The X - r a y st~.uc~ural analysis of the polymer was made with the URS-60 instnunent, usn~ a plate camera and CuK~ radiation filtered through a nickel filter. Cold-pressed tablets were used as samples. The heat resistance in a vacuum was determined from the gas liberation by the method described m another communication [16]. That in air was determined by thermogra~hnetry in a derlvatograph. The temperature gradient was 5°C/min. The thermomechanical curves were recorded on the instrument described by Gerasimov and others [17]; the temperature gradient was here 2°C]min and the load 3 kg/cm z.
CONCLUSIONS (1) Solution a n d interface p o l y c o n d e n s a t i o n s were used t o p r o d u c e a r o m a t i c p o l y a m i d e s containing phenyl, cyclohexyl, phthalide, a n t h r o n e a n d d i h y d r o a n t h r a c e n e groups in t h e branch. (2) T h e influence o f t h e chemical s t r u c t u r e a n d o f t h e synthesis m e t h o d s a n d t h e solubility, ,;,racture, h e a t resistance a n d t h e r m a l stability, M W D a n d o t h e r properties, was studied on p o l y t e r e p h t h a l a m i d e s w i t h b u l k y s u b s t i t u e n t s i n t h e branches. Translated by K. A. A L I ~
REFERENCES 1. R. A. DINE-HART, B. L MOORE and W. W. WRIGHT, J. Polymer Sci. B$: 3~9, 1964 2. Ye. P. KRASN0V, V.M. SAVINOV, L. B. SOKOLOV, V. I. LOGUNOVA, T. A. POLYAKOVA, and V. K. BELYAK0V, Vysokomol. soyed. 8: 380, 1966 (Translated in Polymer Sci. U.S.S.R. 8: 3, 413, 1966) 3. S. V. VINOGRADOVA, V. V. KORSHAK, Ya. S. VYGODSKH and V.I. ZAITSEV, Vysokotool. soyed. Ag: 653, 658, 1967 (Translated in Polymer Sei. U.S.S.R. 9: 3, 731, 11967) 4. S. N. KHAR'KOV, A. S. CHEGOLYA, Ye. P. KRASNOV, L. P. GRECHUSHNEKOVA, G. A. KURAKOV and V. A. PANTAYEV, Vysokomol. soyed. A l l : 2053, 1969 (Translated m Polymer Sci. U.S.S.R. 11: 9, 2353, 1969) 5. U. S. Pat. No. 3068188, 1957 6. V. M. SAVINOV, G. A. KUZNETSOV, V. D. GERASIMOV and L. R. SO]KOLOV,Vysokotool. soyed. Bg: 590, 1967 (Not translated in Polymer Sci. U.S.S.R.) 7. R. N. GRIBOV, V. A. MYAGKOV and I. F. DEVNINA, Sintetmheskie volokn~ (Synthetm Fzbres). p 66, Izd. "Khuniya", 1969
I. N. TOPCHIEVAe$ a/.
918
8. s. R. RAFIKOV, S. A. PAVLOVAand I. I. TV]gRDO~HI.E~OVA, Metody opredeleniya molekulyarnykh vesov i poludispersnosti vysokomolekulyarnykhsoyedinenii (Molecular Weight and Polydisperslty Determination Methods for High Polymers). p. 64, Izd. Akad. Nauk SSSR, 1963 9. German Pat. No. 497628, 1928 10. H. WEIL, E. SAPPER, E. KR:d~MER,K. KL~TER and H. SELBERG, Ber. 61: 1299, 1928 11. G. SCHWARZENBACHand M. BRANDERBERGER, Helv. China. Acta $0: 1253, 1937 12. British Pat. No. 467824, 1935 13. German Pat. No. 488612, 1926 14. C. PADOVA, Comtp. rend. 149: 218, 1909 15. R. ADAMS (Ed.), Organic Reactions, vol. 1, Izd. mostr, hr., p. 203, 1948 (Russian translation) 16. Ye. P. KRASNOV and L. B. SOKOLOV, Sb.: Khimicheskie svoistva 1 modifilcatsiya polimerov (In: The Chemical Properties and Modifications of Polymers). p. 275, Izd. "Nauka", 1964 17. V. D. GERASIMOV, G. A. KUZNETSOV and L. N. FOMENKO, Zavod. labor. 29: 256, 1963
THE
POLYOXYETHYLENE E T H E R OF NoBENZOYLHISTIDINE AS A MODEL OF ALLOSTERIC E N Z Y M E ASSOCIATION*
I. N. TOPCHIEVA, A. B. SOLOV'EVA, B. I. KURGA~OV and V. A. KABANOV M. V. Lomonosov State University, Moscow
(Received 21 July 1970) THE temperature dependence of the 1~-nitrophenyl acetate (NPA) hydrolysis rate, catalysed by the polyoxyethylene ether of the N-benzoylhistidine (POBH), was investigated [1]. An important finding was the detection of sensitivity to the eonformational changes and chemical properties of the polymeric catalyst (PC), which took place when the temperature changed. These changes were associated with changes in the contribution by non-polar (hydrophobic) reactions to the stabilization of one or the other conformation. J u s t as interesting was the s t u d y of the effect of the p H of medium, the substrate, the reaction product, and of various other substances, on the conformational state of PC, and therefore its catalytic activity (efficiency). The aim of the work reported here was the study of conformation transitions in POBH, which took place as a result of the p H changes in the presence of NPA and the reaction product, p-nitrophenol (NP), which led to catalytic property changes of PC. * Vysokomol. soyed. AI4: No. 4, 825-837, 1972.