Acetylene terminated aspartimides are prepared using two methods. In the first, an amino-substituted aromatic acetylene is reacted with an aromatic bismaleimide in a solvent of glacial acetic acid and/or m-cresol. In the second method, an aromatic diamine is reacted with an ethynyl containing maleimide, such as N-(3-ethynylphenyl) maleimide, in a solvent of glacial acetic acid and/or m-cresol. In addition, acetylene terminated aspartimides are blended with various acetylene terminated oligomers and polymers to yield composite materials exhibiting improved mechanical properties

Connell, John W.

Havens, Stephen J.

Hergenrother, Paul M.

English

NASA Technical Reports Server

United States Patent 
Hergenrother et al. 
[54] N43-ETHYNYLPHENYL)MIMIDE 
[75] Inventors: Paul M. Hergenrother, Yorktown; 
John W. Connell, Newport News; 
Stephen J. Havens, Newport News, 
all of Va. 
represented by the Administrator of 
the National Aeronautics and Space 
Administration, Washington, D.C. 
[73] Assignee: The United States of America as 
[21] Appl. No.: 391,692 
[22] Filed: Aug. 10,1989 
Related U.S. Application Data 
[a] Division of Ser. No. 328,392, Mar. 24, 1989, Pat. No. 
4,889,912, which is a continuation-in-part of Ser. No. 
87,375, Aug. 20, 1987, abandoned. 
[51] ht. C l . 5  ............................................ CO7D 207/44 
[52] U.S. Cl. .................................................... 548/549 
[58] Field of Search ......................................... 548/549 
[11] Patent Number: 4,937,356 
[45] Date of Patent: Jun. 26, 1990 
[561 References Cited 
U.S. PATENT DOCUMENTS 
4,500,719 2/1985 Oga et al. ............................ 548/549 
Primaly Examiner-David B. Springer 
Attorney, Agent, or Firm-George F. Helfrich; John R. 
Manning; Charles E. B. Glenn 
Acetylene terminated aspartimides are prepared using 
two methods. In the first, an amino-substituted aromatic 
acetylene is reacted with an aromatic bismaleimide in a 
solvent of glacial acetic acid and/or m-cresol. In the 
second method, an aromatic diamine is reacted with an 
ethynyl containing maleimide, such as N-(3-ethynyl- 
phenyl)maleimide, in a solvent of glacial acetic acid 
and/or m-cresol. In addition, acetylene terminated as- 
partimides are blended with various acetylene termi- 
nated oligomers and polymers to yield composite mate- 
rials exhibiting improved mechanical properties. 
WI ABSTRACT 
1 Claim, No Drawings 
https://ntrs.nasa.gov/search.jsp?R=19910005106 2020-03-24T06:57:21+00:00Z
1 
4,937,356 
mides) [F. Grundschober and J. Sambeth (To SOC. 
Rhodiacita), U.S. Pat. No. 3,533,996 (Oct. 13, 197011. 
In most cases, less than a stoichiometric amount of an 
aromatic diamine is reacted with a bismaleimide to yield 
a low or intermediate molecular weight polyasparti- 
mide terminated with maleimide groups. Upon heating, 
the terminal maleimide groups react to yield a cross- 
linked resin having less toughness than the linear po- 
lyaspartimides but with improved solvent resistance 
and higher use temperature. The degree of crosslinking 
can be controlled to a large extent by the stoichiometry. 
A common material of this type is Kerimid 601 (avail- 
able from Rhone Poulenc), used extensively in printed 
circuit boards. 
ORIGIN OF THE INVENTION 
The invention described herein was jointly made by 
employees of the United States Government and con- 
tract employees in the performance of work under a 
NASA Contract and Grant and is subject to the provi- 
sions of Public Law 96-517 (35 USC 202) in which the 
contractor has elected not to retain title and/or the 
provisions of Section 305 of the National Aeronautics 
and Space Act of 1958, as amended, Public Law 85-568 
(72 Stat. 435; 42 USC 2457). 
5 
10 
15 The acetylene terminated aspartimides (ATA) of this 
invention present new compositions of matter. The 
urouerties of cured acetvlene terminated asuartimides 
CROSS-REFERENCE TO RELATED 
APPLICATION 
The application is a division of U.S. patent applica- heiimilar to those of thd cured unformulatei bismalei- 
tion Ser. No. 328,392, filed Mar. 24,1989, which is now mides but they have significantly higher toughness. In 
U.S. Pat. No. 4,889,912, which is a continuation-in-part 20 addition, the acetylene terminated aspartimides are 
of US. patent application Ser. No. 087,375, filed Aug. formed as stereoisomers (d, 1 and meso isomers), and as 
20, 1987, abandoned. such have lower melt temperatures than bismaleimides 
with similar chemical structure. Since they are a mix- 
BACKGROUND OF THE INVENTION ture of isomers, they also melt over a broad temperature 
Structural resins with a favorable combination of 25 ranee. Both of these factors make acetvlene terminated 
properties such as long term environmental durability 
over a temperature range of -54' to 220" C., damage 
tolerance, and solvent resistance are required for use in 
hot areas on military and commercial aircraft. Commer- 
cially available bismaleimide resins such as Compimide 
353 (available from Bootsflechnochemie) and XU-292 
(available from Ciba/Geigy Corporation) previously 
have been formulated with other components to en- 
hance properties such as melt processability and tough- 
ness. These formulated systems have found use in a 
variety of applications such as composite matrices and 
adhesives for use at temperatures in excess of those at 
which epoxy systems can perform. 
Polyaspartimides are commonly synthesized by reac- 
tion of aromatic bismaleimides with aromatic diamines. 
These polymers have a repeat unit of the following 
general formula: 
r o  0 1 
L N H - M - N H  1 I I N-Ar-N I 
1. 
where Ar and Ar' are divalent aromatic radicals, such 
as 1,3-phenylene or 4,4'-oxydiphenylene. 
High molecular weight polyaspartimides are known 
[J. V. Crivello, J.  Polymer Sci, 11, 1185(1973)] and can 
form tough, flexible films with good tensile properties 
and can be compression molded. However, uncross- 
linked polyaspartimides are susceptible to solvent at- 
tack, especially in a stressed condition, and upon expo- 
sure undergo solvent induced stress crazing and crack- 
ing. In addition, polyaspartimides are generally soluble 
in dipolar solvents such as N,N-dimethylformamide, 
dimethyl sulfoxide, N,N-dimethylacetamide, N-methyl- 
pyrrolidinone, phenol, and m-cresol. Melt condensation 
of aromatic diamines and bismaleimides has been re- 
ported to yield cross-linked polymers (polyasparti- 
- 
aspartimides more amenable to process into adhesive 
tape and prepreg via melt technique than comparable 
bismaleimides. 
The acetylene terminated aspartimides can be readily 
30 blended with acetylene terminated arylene ether oligo- 
mers and polymers to yield cured resins with high 
toughness. The crosslink density can be controlled by 
varying the ratio of acetylene terminated aspartimide to 
acetylene terminated arylene ether oligomers or poly- 
35 mers and also by varying the length and chemical struc- 
ture of the linear segment in the acetylene terminated 
arylene ether oligomers or polymers. The acetylene 
terminated aspartimides can also be blended with acety- 
lene terminated polysulfones to yield resins with high 
Accordingly, it is an object of this invention to pro- 
vide a method of preparing acetylene terminated aspar- 
timides. 
A further object of this invention is to provide acety- 
45 lene terminated aspartimides that are useful as adhe- 
sives, coatings, films and composite matrices. 
A further object of the present invention is to provide 
blends of acetylene terminated aspartimides and other 
acetylene terminated oligomers and polymers that are 
50 useful as adhesives, coatings, films, membranes and 
composite matrices. 
40 fracture toughness. 
SUMMARY OF THE INVENTION 
According to the present invention, the foregoing 
55 and additional objects were attained by synthesizing 
aspartimide oligomers and polymers containing termi- 
nal acetylene groups. Acetylene terminated asparti- 
mides were prepared using two methods. In the first, an 
amino-substituted aromatic acetylene was reacted with 
60 an aromatic bismaleimide in a solvent of glacial acetic 
acid and/or m-cresol. In the second method, an aro- 
matic diamine as reacted with an ethynyl containing 
maleimide, such as N-(3-ethynylphenyl) maleimide, in a 
solvent of glacial acetic acid and/or m-cresol. In addi- 
65 tion, acetylene terminated aspartimides were blended 
with various acetylene terminated oligomers and poly- 
mers to yield composite materials exhibiting improved 
mechanical properties. 
4,937,3 5 6 
3 
DETAILED DESCRIPTION OF THE 
INVENTION 
The present invention comprehends synthesizing 
acetylene terminated aspartimides using two methods. 5 
In the fust, an amino-substituted aromatic acetylene is 
reacted with an aromatic bismaleimide. The general 
reaction sequence is represented by the following equa- 
tion: 
4 
-continued 
-olQLsoz~o-. 
Solvent \1 
where x is selected from a group of radicals consisting 30 
of nil, CH2, 0, S, C=O, SOa C(CH3)z1 C(CF3)2, 
-0 
35 
and mixtures thereof. Linkage of the bismaleimide may 
be para, para; meta, meta; or meta, para. Any aromatic 
0 0 amine containing a terminal acetylenic group such as 
3-aminophenylacetylene or 4aminophenylacetylene 
40 may be used. Any polar solvent may be used. Particu- 
larly beneficial results were obtained using glacial 
acetic acid or m-cresol containing a small amount of 
glacial acetic acid. 
The aromatic bismaleimide may be a maleimide-ter- 
45 minated polyarylene ether oligomer. This oligomer may 
be prepared by reaction of an aminophenol such as 
4-aminophenyl-4'-hydroxyphenyl-2,2-propane with the 
appropriate amounts of a diphenol and an activated 
dihaloketone in order to produce an amine-terminated 
50 polyarylene ether oligomer. This diamino oligomer 
may then be converted to the bismaleimide by reaction 
with maleic anhydride followed by cyclodehydration. 
- O Q O - ,  -OQ0-, 
-!@-,-!Q0 
II 
C--, 
-oQe@jo- 
-olQlcHz@j -, 
55 
60 
65 
4,937,35 6 
5 6 
IL 
+ +  Q 
N 
- 
I 
C 
0 
O=G 
@ 0 I 
6 
a 
I 
0=3 
4,937,356 
7 
Alternately, the maleimide-terminated polyarylene 
ether oligomers can be made in one step by the reaction 
of compounds such as 
0 
II 
0 
with the appropriate amounts of diphenol and activated 
dihalo compound. 
In the second method, acetylene terminated asparti- 
mides are prepared by reacting an aromatic diamine 
with an ethynyl containing maleimide. The general 
reaction sequence is represented by the following equa- 
tion: 
5 
10 
15 
20 
25 
8 
-continued 
and mixtures thereof. Linkage of the diamine may be 
para, para; meta meta; or meta, para. Any ethynyl con- 
taining maleimide such as N-(3-ethynylphenyl) malei- 
0 
n H 2 N a x a N H 2  + 2  C N G  II 
C E  CH 
0 
50 
where x is selected from a group of radicals consisting 
of nil, CH2, 0, S ,  M, S02, C(CH3h C(CF3)2, mide or N-(4ethynylphenyl) maleimide may be used. 
As in method 1 any of various polar solvents may be 
55 used. 
The aromatic diamine may be an amine-terminated 
polyarylene ether oligomer as previously described for 
-OQO-, -"Q0-, the first method. 
The present invention further comprehends novel 
60 composite materials formed by blending acetylene ter- 
minated aspartimides with various acetylene termined 
polymers. The acetylene terminated aspartimide from 
the reaction of 3-aminophenylacetylene and N,N-bis- 
maleimido-4,4'-diphenylmethane was blended with an 
65 equal weight of an acetylene terminated sulfone oligo- 
mer (the number of average molecular weight of the 
sulfone segment was approximately 9000 g/mole). Such 
oligomers have the following general formula: 
0 0 -!0!-,-iQo 
It 
C--, 
9 
4,937,3 5 6 
10 
where n is an integer from 3 to 59. The resulting blend 
was then processed and cured at a maximum tempera- 
dure similar to that disclosed in U.S. Pat. NO. 4,431,761: 
H C I C  C 3 C H  
ture range of 230"-250" C. A molded specimen pre- 
pared therefrom showed a significant improvement in 
fracture toughness with a KlC (stress intensity factor) of 
approximately 1400 psi.in4 compared to unblended acet- 
wherein n is an integer representing 3 to 60 repeat units. 
Linkage of the phenylethynyl groups may be either 
meta or para. Ar is a divalent aromatic radical selected 
from the group consisting of: 
ylene terminated aspartimides. This specimen was not 
affected upon exposure to methylene chloride or other 50 
solvents. A 30% solids solution of the blend in methy- 
lene chloride was used to impregnate carbodgraphite 
fabric. The prepreg was stacked and cured in an auto- wherein X is selected from the group consisting of 
clave by holding at 149" C. for 20 minutes and at 177" C. O=C and SOz, and y is a bond, or is selected from the 
for two hours under 80 psi. The composite was post- 55 group consisting of 0, S, CHz, C=O, SOz, C(CH3)2), 
cured in a press at 232" C. for one hour under 100  psi to and C(CF3)2, Ar' is a divalent aromatic radical selected 
give a fmal composite with a calculated resin content of from the group consisting of: 
approximately 41%. At 25" C., flexural strength, flex- 
ural modulus, and short beam shear strengths were 
determined to be 93,500 psi, 7,575,000 psi, and 8600 psi, 60 
respectively. At 177" C., the respective values were 
87,800 psi, 6,266,000 psi, and 7200 psi. 
The invention is not limited to this example of blends 
of the acetylene terminated aspartimides with sulfone 
oligomers but includes blends in varying proportions of 65 
the acetylene terminated aspartimides with all acetylene 
terminated polyarylene ethers of the following general 
structure which can be prepared according to a proce- 
O,Q.-@lxQJ 
4,937,356 
11 12 
-continued EXAMPLE I1 
Synthesis of an ATA by Reaction of 
N-(3-ethynylphenyl)maleimide with 
5 4,4'-diaminodiphenylmethane 
N-(3-ethynylphenyl)malehide 
Maleic anhydride (79.6 g, 0.81 mole) was added to a 
solution of distilled 3-aminophenylacetylene (95.1 g, 
0.81 mole) dissolved in 500 mL of dry N,N-dime- 
lo thylacetamide (DMAc) at 5"-10" C. After addition, 
another 300 mL of DMAc was added and the mixture 
stirred at room temperature for two hours. Nickel ace- 
tate tetrahydrate (0.8 g) and acetic anhydride (300 mL) 
were added to the reaction mixture and stirring was 
15 continued for 12 hours at room temperature to affect 
cyclodehydration. The crude product was isolated by 
precipitation in water and recrystallized from methanol 
to provide N-(3-ethynylphenyl)rnaleimide (128 g, 80% 
yield) as a yellow crystalline solid, mp 129"-131" C. 
73.09%; H, 3.58%; N, 7.10%. Found: C, 72.94%, H, 
3.61%; N, 7.04%. 
Acetylene Terminated Asparthide (ATA) 
wherein X is a bond or a selected from the group: CH2, 
0, S, c--O, S02, C(CH3)2, and C(CF3)2. 
N-(3-ethynylphenyl)maleimide (13.80 g, 0.070 mol) 
that this invention is not limited to the examples herein and 4,4'-diaminodiphenylmethane (6.94 g, 0.035 mole) 
described. Additionally, this invention includes blends were dissolved in 200 mL Of glacial acetic acid and the 
of acetylene terminated asp,&-des with acetylene solution heated to reflux for 24 hours under a nitrogen 
atmosphere. The solution was added to water to precip- 
minated imide oligomers, acetylene terminated ester 30 tive yield as a mixture of d, 1 and meso isomers, mp 
oligomers and various other acetylene terminated oligo- 110"-115" c. Elemental analysis calculated for 
mers. CyH28N404: C, 74.98%; H, 4.76%, N, 9.45%. Found: 
C, 74.81%, H, 4.80%; N, 9.38%. From differential scan- 
EXAMPLES ning calorimetric analysis of this ATA, a melting endo- 
EXAMPLE I 35 therm was detected at 119" C. and an exothermic peak 
due to reaction of acetylene groups detected at 209" C. 
Synthesis of an ATA by reaction of From thermogravimetric analysis, this ATA after cur- 
3-aminophenylacetylene with ing at 300" C. for 15 minutes exhibited 5% weight loss 
N,N'-bismaleimido-4,4'-diphenylmethane. in air at 385" C. 
A solution of N,N-bismaleimido-4,4'-diphenylme- EXAMPLE I11 
thane (38.34 g, 0.10 mole) and distilled 3-aminopheny- Preparation of a 1: 1 blend of the ATA prepared from 
lacetylene 23.43 g, 0.20 mole) was dissolved in 100 mL the reaction of 3-aminophenyIacetylene with N,N'-bis- 
of m-cresol containing 4 ml glacial acetic acid. The maleimido-4,4'-diphenylmethane and an acetylene ter- 
resulting solution was stirred under a nitrogen atmo- 45 minated sulfone oligomer (number average molecular 
sphere with the temperature of the reaction mixture weight Of sulfone 
at c. for 48 hours. The solvent The ATA from the reaction of 3-aminophenylacety- lene with N,N-bismaleimido-4,4'-diphenylmethane (50 was removed under vacuum and the residue dried g) and an acetylene terminated sulfone oligomer (num- 
under vacuum at %' c* A quantitative yield Of 50 ber average molecular weight of sulfone segment, 8890 
light yellow solid was obtained which was a mixture of g/mole) (50 g) were dissolved in 200 mL of chloroform 
d, 1 and meso isomers, mp 104'-110" C. The material with warming. The solution was mixed and the chloro- 
resisted recrystallization but an analytically pure sample form allowed to evaporate. The residue was crushed, 
was obtained by precipitation from a chloroform solu- allowed to air dry, and then dried under vacuum at 90" 
tion with methanol. ~ l ~ ~ ~ ~ ~ a l  analysis calculated for 55 C. Solutions of this blend in 1,Cdioxane were used to 
coat adhesive specimens and methylene chloride solu- 
C, 75.04% H, 4.93%; N, 9.29%. From differential scan- The blend can also be prepared directly in 1,44ioxane. 
ning calorimetry analysis (DSC) ofthis ATA, a melting For the preparation of moldings, the blend was prere- 
endotherm was detected at 81' C. and an exothermic acted at 200" C. for ten minutes in order to decrease 
peak due to reaction of the acetylene groups was de- melt flow. From TGA this blend after curing at 250" C. 
tected at 266' c .  From thermogravimetric analysis for one hour exhibited 5% weight loss in air at 386" C. 
(TGA) at a heating reate of 2.50 C. per minute, this and in nitrogen at 392" C. By isothermogravimetric 
ATA after curing at 250" c. for one hour, exhibited 5% analysis at 260" C. in circulating air, this cured blend exhibited 10% weight loss after 110 hours. weight loss in air at 370" C. and in nitrogen at 355" C. 65 The invention is not limited to these 
By isothermogravimetric analysis at 260" C. in circulat- What is claimed is: 
ing air, this cured ATA exhibited 17% weight loss after 1. N-(3-ethynylphenyl)maleimide. 
110 hours. * I * * *  
-' and 
, 
20 Elemental analysis calculated for C12H7N02: C, 
It should become obvious to those skilled in the art 25 
terminated phenylquinoxaline oligomers, ter- itate the ATA as a light solid in nearly quantita- 
40 
8890 g/mO1e)* 
C37H28N404: c, 74.98% H, 4.76%, N, 9.45%. Found: tions were used to prepare carbon-graphite prepreg. 


N-(3-ethynylphenyl)maleimide

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