The compound N-(3-ethynylphenyl)maleimide (NEPMI) was used to prepare thermally stable, glassy polyimides which did not exhibit glass transition temperatures below 500 C. NEPMI was blended with the maleimide of methylene dianiline (BMI) and heated to form the polyimide. NEPMI was also mixed with Thermid 600 R, a commercially available bisethynyl oligomeric material, and heated to form a thermally stable, glassy polyimide. Lastly, NEPMI was blended with both BMI and Thermid 600 R to form thermally stable, glassy polyimides

Gerber, Margaret K.

St.clair, Terry L.

English

NASA Technical Reports Server

I lllll111111111111111111111111 llllll 11111111 
US005 189127A 
United States Patent [I91 [ i l l  Patent Number: 5,189,127 
Gerber et al. [45] Date of Patent: Feb. 23, 1993 
CROSSLINKED POLYIMIDES PREPARED 
FROM 
Inventors: Margaret I(. Gerber, Cincinnati, 
N-(3-ETHYNYLPHENYL)MALEIMIDE 
Ohio; Terry L. St. Clair, Poquoson, 
Va. 
The United States of America as 
represented by the Administrator of 
the National Aeronautics and Space 
Administration, Washington, D.C. 
Assignee: 
Appl. NO.: 801,867 
Filed: Dec. 3,1991 
Related U.S. Application Data 
Continuation-in-part of Ser. No. 528,666, May 18, 
1990, abandoned. 
Int. ( 3 . 5  ............................................ C08F 222/40 
U.S. c1. .................................... 526/262; 526/285; 
528/322 
Field of Search ................. 526/262, 285; 528/322 
~561 References Cited 
U.S. PATENT DOCUMENTS 
4,861,882 SA989 Hergenrothcr et al. ............ 544/216 
4,889,912 12/1989 Hergenrother et al. ............ 528/125 
4,931,356 6/1990 Hergenrother et al. ............ 548/549 
Primary Examiner-Harold D. Anderson 
Attorney, Agent, or Firm-George F. Helfrich 
The compound N-(3ethynylphenyl)maleimide 
(NEPMI) was used to prepare thermally stable, glassy 
polyimides which did not exhibit glass transition tem- 
peratures below 500' C. NEPMI was blended with the 
maleimide of methylene dianiline @MI) and heated to 
form the polyimide. NEPMI was also mixed with Ther- 
mid 600 8, a commercially available bisethynyl oligo- 
meric material, and heated to form a thermally stable, 
glassy polyimide. Lastly, NEPMI was blended with 
both BMI and Thermid 600 @ to form thermally stable, 
glassy polyimides. 
[571 ABSTRACT 
10 Claims, No Drawings 
https://ntrs.nasa.gov/search.jsp?R=19930010199 2020-03-24T07:29:59+00:00Z
* 9 5,189,127 I 
CROSSLINKED POLYIMIDES PREPARED FROM 
N-(3-ETHYNYLPHEhTL)MALEIMIDE 
ORIGIN O F  THE INVENTION 
The invention described herein was made in the per- 
formance of work under a NASA contract and is sub- 
ject to the provision of Section 305 of the National 
Aeronautics and Space Act of 1958, as amended, Public 
Law 85-568 (72 Stat. 435; 42 USC 2457). 
CROSS-REFERENCE 
This application is a continuation-in-part of copend- 
ing application Ser. No. 528,666, filed May 18, 1990, 
now abandoned. 
BACKGROUND O F  THE INVENTION 
1. Field of the Invention 
The present invention relates generally to polyimides 
which are suitable for high temperature applications as 
a result of their high or nondetectable glass transition 
temperatures and their high thermooxidative stabilities. 
It relates particularly to three types of polyimides 
which are prepared from monomers containing carbon- 
carbon double and/or triple bonds, in particular N43- 
ethyny1phenyl)maleide OIJEPMI). 
2. Description of Related Art 
Polymers prepared from the reaction of organic com- 
pounds containing pendant ethynyl groups or organic 
oligomers containing pendant ethynyl groups are well 
known for their thermooxidative stability and excep- 
tionally high glass transition temperatures. Likewise, 
organic compounds or oligomers containing activated 
carbon-carbon double bonds and imide moieties (Le. 
maleimides) can be used to prepare thermally stable 
polymers. 
Hergenrother et al. (US. Pat. No. 4,889,912 and U.S. 
Pat. No. 4,937,356) prepared acetylene terminated as- 
partimides by reacting an aromatic diamine with 
NEPMI. These acetylene terminated aspartimides were 
blended with acetylene terminated polyarylene ethers 
or sulfone oligomers to yield polymers with improved 
mechanical properties such as fracture toughness. 
Hergenrother et al. (US. Pat. No. 4,861,882) also 
prepared ethynyl terminated imidothioethers by react- 
ing a dimercaptan with NEPMI. These ethynyl termi- 
nated imidothioethers were then blended with other 
ethynyl terminated oligomers to produce resin blends 
which are useful as adhesives, coatings, and films. The 
glass transition temperatures of these blends ranged 
from 193"-245" C. 
SUMMARY O F  THE INVENTION 
The compound N-(3ethynylphenyl)maleimide 
(NEPMI) has the following structural formula: 
0 
This monomer is highly reactive due to its two types of 
unsaturation (double and triple bonded carbons). The 
ethynyl group allows for copolymerization with other 
ethynylcontaining monomers and oligomers and the 
L 
maleimide group allows for copolymerization with 
maleimide monomers and oligomers. 
The highly reactive nature of NEPMI is demon- 
strated when it is heated past its melting point of 130' C. 
5 Depending on the heating rate, the liquid form of 
NEPMI exhibits an intense exotherm in the region of 
155'-248' C. This exotherm is so strong that active 
cooling is necessary in order to dissipate the heat. The 
resulting polymers do not exhibit glass transitions below 
lo 500' C. These characteristics are also demonstrated by 
compounds having the following general structural 
formula: 
0 
II 15 
r.-.-c= CH 
'i/ 
II 
20 0 
where Ar is any aromatic moiety. 
An object of the present invention is to provide high 
temperature polyimides by reacting NEPMI with bi- 
25 Ethynyl-containing monomers and/or oligomers and 
heating them to a temperature where they react. 
Another object is to provide high temperature polyi- 
mides by reacting NEPMI with bismaleimide mono- 
mers and/or oligomers and heating them to a tempera- 
Another object is to provide high temperature polyi- 
mides by reacting NEPMI with mixtures of bisethynyl 
and bismaleimide monomers and/or oligomers and 
35 heating them to a temperature where they react. 
DESCRIPTION O F  THE PREFERRED 
EMBODIMENTS 
EXAMPLE 1 
High temperature polymers were prepared by heat- 
ing 5-10 mg samples of NEPMI in an open pan at heat- 
ing rates of 1" C./min., 10' C./min., 20' C./min., 50' 
C./min. , and loo" C./min. using a DuPont 1090 Ther- 
mal Analyzer. Table 1 lists the melt onset, exotherm 
45 temperature and intensity, and temperature for 5% 
weight loss in air for each polymer prepared. For com- 
parison, samples of the maleimide of methylene diani- 
line (BMI), and samples of Thermide 600 8, a bisethy- 
nyl oligomeric compound available from National 
50 Starch, were heated at heating rates of 10' C./ min. and 
50' C./min. using the same thermal analyzer. These 
results are also recorded in Table 1. 
TABLE 1 
30 ture where they react. 
40 
55 Pure Reactants 
EX- Temp. 
' Melt O ~ ~ C I U I  EX- 54bWt. 
Sample 
60 NEPMI 
NEPMI 
NEPMI 
NEPMI 
NEPMI 
Heating 
Rate 
1' c./min 
lo' C./& 
20' chin 
50' C./min 
loo' c./ 
min 
lo' c./min 
50' c./min 
lo' c./min 
50' c./min 
Onset 
W.) 
130.5 
131.2 
131.7 
135.7 
135.2 
151.7 
154.7 
Not 
observed 
Not 
Temp. 
CC.) 
155 
200 
215 
244 
248 
246 
246 
2% 
297 
othelm lossin 
Intensity lir 
low 405' c. 
low 412' C. 
moderate 42WC. 
high 410'C. 
high 412-c. 
very low 42W c. 
very low 410' C. 
low 508' c. 
moderate 503'C. 
5.189.127 
3 
TABLE 1-continued 
Pure Reactants 
EX- Temp. 
Melt otherm Ex- 5% Wt. 
Heating Onset Temp. otherm lossin 
Sample Rate ('C.) ('C.) Intensity air 
observed 
4 
EXAMPLE 2 10 
NEPMI was blended in various ratios with the malei- 
mide of methylene dianiline (BMI) and thermally poly- 
merized as described in Example 1. BMI has the follow- 
ing structural formula: 15 
where Ar is any aromatic moiety and n= 1-50. 
EXAMPLE 3 
NEPMI was also blended in various ratios with the 
ethynyl-containing oligomeric compound Thermid 
600Q and thermally polymerized as described in Ex- 
ample 1. Thermid 600 @ has the followhg structural 
formula: 
P 0 
0 0 
0 0 
Table 2 shows the heating rate, melt temperature, exo- 
therm temperature, temperature of 5% weight loss in 
air, and glass transition temperature (Tg) for the result- 
ing polymer blends and is compared to BMI and Ther- 
mid 600 Q control polymers. It is evident from the data 
that the presence of NEPMI offers a significant im- 
provement in the Tg of these polymers. 
TABLE 2 
Ratio of 
NEPMV 
BMI 
9 0 A O  
90/10 
80/20 
80/20 
70/30 
70/30 
Polymers from NEPMI-BMI Blends 
Temp. 
Melt Exotherm 5% 
Heating Temp. Temp. wt. loss Tg 
Rate CC.) ('C.) CC.) CC.) 
10'C./min 122.8 210 418 >500 
WC./min 131.3 240 432 >5W 
10' C./min 107.9 208 415 > 5 0 0  
WC./min 110 250 410 >Mo 
10'C./min 109.4 214 430 >Mo 
WC./min 111.9 250 420 >Mo 
120 
135 
120 
30 
35 
40 
45 
50 
where n=  1-10. 
Table 3 contains data on the resulting NEPMI-Ther- 
mid 600Q blends as compared to BMI and Thermid 
600 @ control polymers. 
TABLE 3 
Polymers from NEPMI-Thermid 600 (13 
Ratio of Temp. 
NEPMI/ Melt Exotherm of 5% 
Thermid Heating Temp. Temp. wt.loss Tg 
600 @ Rate ('C.) CC.) ('C.) ('C.) 
90/10 10'C./min 127.6 210 415 >Mo 
90/10 WC./min 131.7 246 438 >SO0 
80/20 10' C./min 127.1 218 432 >5W 
80/20 50'C./min 133.1 254 396 > 5 0 0  
70/30 10'C./min 128 i2I.8 435 >500 
70/30 WC./min 132 252 440 >m 
60/40 lO'C./min 127 228 378 >500 
60/40 WC./min 129 276 432 >Mo 
%/SO 10'C./min 128 230 410 >Mo 
50/50 WC./min 130 278 462 >Mo 
20/80 10'C./min 128 246 455 >m 
m/80 WC./min 130 288 500 >m 
BMI 10'C./min 151.7 246 420 290 
Thermid IO'C./min Not 250 508 305 
m m  obrervcd 
133 
126 410 >Mo 55 Although Termid 600Q was used in this example, 
60/40 10'c./min 109.4 211 
60/40 50*c./min 113 25 1 420 > ~ o  other bisethynyl terminated oligomers known to those 
50/M 10'c./min 109.9 212 442 >500 skilled in the art may also be employed. These com- 
50/M 50' C./min 113 248 418 >Mo pounds have the following general structure: 
80/20 10'c./min 110 224 428 >Mo 
W/20 50'C./min 113 252 418 >Mo 
BMI 10'C./min 151.7 246 420 290 where Ar is any aromatic moiety and n= 1-50. 
Thermid 10'C./min None 250 508 305 
6cQQ 
129 HC=C-(Ar),--C=CH 
137 
EXAMPLE 4 
Polymers were made by heating blends of NEPMI, 
Thermid 600@, and BMI in various ratios. The data is 
presented in Table 4 and compared to BMI and Ther- 
mid 600 @ control polymers. 
65 
Although BMI was used in this example, other bis- 
maleimides can also be used which have the following 
structure: 
5,189,127 
5 
TABLE 4 
Ternary Blends 
Ratio of Temp. 
NEPMI/ of 5% 
BMI/ Melt Exotherm weight 
Thermid Heating Temp. Temp. loss Tg 
600 8 Rate (T.) (T.) (T.) ('C.) 
1/1/1 Io" C./min 105 230 468 >5M) 
1/1/1 50" C./min 114 260 458 >Mo 
1/0.5/3 10' C./min 1 1 1  247 450 >Mo 
1/0.5/3 M' C./min 125 290 482 >Mo lo 
1/3/2 Io'C./min 107 236 462 >Mo 
1/3/2 M'C./min 116 256 450 >so0 
BMI 10"C./min 151.7 246 420 290 
Thermid 10"C./min None 250 508 305 
5 
The utility of these polymers is dependent on their 
ability to be formed from monomers and oligomers 
which melt and polymerize without the evolution of 
volatiles. The presence of NEPMI in the polymer re- 
sults in an increase in crosslink density, and thus, they 
do not exhibit a glass transition ( T g )  below 500' C. 
These polymers are useful as high temperature compos- 
ite matrix resins for supersonic aircraft structures and 
mainframe and engine applications where high Tg is a 
requirement. 
What is claimed as new and desired to be secured by 
Letters Patent of the United States is: 
1. A thermally stable, glassy, crosslinked polymer 
prepared from a monomer composition consisting es- 
sentially of at least one ethynyl imide (I) having the 
following general structural formula: 
0 
I1 
0 
20 
25 
30 
6 
continued 
and 
HC=C-(Ar),-CECH (I10 
where Ar is any aromatic moiety and n= 1-50; and said 
polymer has a glass transition temperature of at least 
500" c. 
2. A thermally stable, glassy, crosslinked polymer 
according to claim 1, wherein (I) has the following 
structural formula: 
0 
3. A thermally stable, glassy, crosslinked according 
to claim 1, wherein (11) has the following structural 
formula: 
4. A thermally stable, glassy, crosslinked polymer 
according to claim 3, wherein the ratio of NEPMI to 
BMI is between about 9O:lO and 20:80. 
5. A thermally stable, glassy, crosslinked polymer 
according to claim 1, wherein (111) has the following 
structural formula: 
0 
0 
where Ar is any aromatic moiety; and a member se- 
lected from the group consisting of: 
(I0 55 
where n= 1-10. 
6. A thermally stable, glassy, crosslinked polymer 
according to claim 5, wherein the ratio of NEPMI to 
(IV) is between about 9o:lO and 20:80. 
7. A thermally stable, glassy, crosslinked polymer 
according to claim 1, wherein (I), (II),and (111) have 
the following structural formulas, respectively: 
0 
II 
7 
5,189,127 
,-continued 
8 
and 
according to claim 7, wherein the ratio of NEPMI to 
BMI to (IV) is 1:0.5:3. 
10. A thermally stable, glassy, crosslinked polymer 
according to claim 7, wherein the ratio of NEPMI to 
BMI to (IV) is 1:3:2. 
where n= 1-10. 
according to claim 7, wherein the ratio of NEPMI to 
BMI to (IV) is 1:l:l. 
9. A thermally stable, glassy, crosslinked polymer 
8. A thermally stable, glassy, crosslinked polymer 2o 
* * * * *  
25 
30 
35 
40 
45 
50 
55 


Crosslinked polyimides prepared from N-(3-ethynylphenyl)maleimide

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