NASA CASE NO.

PRINT FIG.

_3ZLICE

i,, _ ,,

The invention disclosed in this document resulted from research in aeronautical and

space activities performed under programs of the National Aeronautics and Space

Administration. The invention is owned by NASA and is, therefore, available for

licensing in accordance with the NASA Patent Licensing Regulation (14 Code of

Federal Regulations 1245.2).

To encourage commercial utilization of NASA-owned inventions, it is NASA policy to

grant licenses to commercial concerns. Although NASA encourages nonexclusive

licensing to promote competition and achieve the widest possible utilization, NASA

will provide the necessary incentive to the licensee to achieve early practical

application of the invention.

Address inquiries and all applications for license for this invention to NASA Patent

Counsel, Langley Research Center, Code 143, Hampton, Virginia 23681-0001.

Serial No." 08/209,512

03/03/94 LaRC

(NASA-Case-LAR-15175-1)

PHENYLETHYNYL TERMINATED IMIDE

OLIGOMERS Patent Application

(NASA. Langley Research Center)

36 p

N95-14185

Unc|as

G3/27 0029860
PHENYLETHYNYL TERMINATED lMlDE OLIGOMERS 

NASA Case No.: LAR 15175-1 

Wholly aromatic polyimides are known for their exceptional thermal, thermooxidative 

and chemical resistance, but are generally difficult to process as structural adhesives or 

composite matrices. The incorporation of ethynyl groups in polyimides is known to 

those skilled in the art. Typically, these groups have been incorporated as terminal 

groups to yield acetylene-terminated imide oligomers. 

By the present invention, a series of phenylethynyl-terminated imide oligomers of 

various molecular weights which can be thermally cured to provide materials that are 

crosslinked, insoluble in common organic solvents and have excellent high temperature 

mechanical properties were prepared. In addition, new amino phenylethynyl 

compounds were prepared which were used to terminate oligomers. 

The novelty of the invention lies in the four phenylethynyl amine compounds which 

were prepared and used to endcap imide oligomers. Phenylethynyl-terminated amide 

acid oligomers and phenylethynyl-terminated imide oligomers with various molecular 

weights and compositions were prepared and characterized. The resulting polyimides 

had excellent solvent resistance, high strength and modulus and good high 

temperature properties. In addition, adhesive panels, composites, films and moldings 

prepared from these oligomers had excellent mechanical properties. 

Inventors: Paul M. Hergenrother Robert G. Bryant 

Address: 304 Old Dominion Rd. P.O. Box 2272 

Yorktown, VA 23692 Poquoson, VA 23662 

SS: SS: 

Employer: NASA LaRC NASA LaRC 

Inventors: Brian J. Jensen Stephen J. Havens 

Address: 127 Branscome Blvd. 390-D Deputv Lane 

Williamsburg, - VA 231 85 New~ort ~ews, VA 23602 - 

Employer: 

SS: 

Lockheed 

Initial Evaluator: Terry L. St. Clair 

Serial No.: 081209,512 

Filed: March 3, 1994 
LAR 15175-1 -1- PATENT APPLICATION

PHENYLETHYNYL TERMINATED IMIDE OLIGOMERS

5

10

Origin of the Invention

The invention described herein was jointly made by employees of

the United States Government and during the performance of work under

a NASA contract and is subject to 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).

Background of the Invention

1. Field of the Invention

15 The present invention relates generally to polyimides, especially

imide oligomers. It relates particularly to a series of phenylethynylterminated imide oligomers which can be thermally cured to resins that

are useful as adhesives, composite matrices, moldings, films and

coatings. The invention also relates particularly to a series of amino

20 phenylethynyl compounds used to terminate the imide oligomers.

25

30

2. Description of Related Art

Polyimides are condensation polymers that can be prepared by

various routes. The most popular route involves the reaction of an

aromatic dianhydride with an aromatic diamine. The intermediate

polyamide acid is either thermally or chemically cyclodehydrated to form

the polyimide which has a repeat unit of the general type

0 0

NyAr' _N_Ar

0 0
LAR 15175-1 -2- PATENT APPLICATION

where Ar' is a tetravalent aromatic radical, which can be as simple as

1,2,4,5-tetrasubstituted benzene, or it may be a bis-4-(o-diphenylene)

having the general structure

5

where X = nil, O, S, SO 2, C = O, etc. Ar' may be any other appropriate

tetravalent radical. Ar is a divalent aromatic radical which may be 1,3-

phenylene, 1,4- phenylene, 4,4'-oxydiphenylene, 4,4'-biphenylene, 4,4'-

10 thiodiphenylene, 4,4'-carbonyldiphenylene, 4,4'-methylenediphenylene or

any other appropriate divalent radical.

Synthesis and characterization of polyimides has been extensively

reported in the literature. The preparation of aromatic polyimides by

reaction of an aromatic dianhydride with an aromatic diamine, followed

15 by thermal cyclization was first reported in 1963 [G. M. Bower and L. W.

Frost, J. Polym. Sci. A1, 3134 (1963)] with patents awarded in 1965

(W. M. Edwards, U. S. Patents 3,179,614 and 3,179,634 and A. L.

Endrey, U.S. Patents 3,179,631 and 3,179,633). Several reviews on

polyimides have been published [C. E. Sroog, "Polyimides" in

20 Encyclopedia of Polymer Sci. and Technology (H. F. Mark, N. G. Gaylord

and N. M. Bikales, ed.) Interscience Pub., New York, 1969, Vol. 11,

pp. 247-272; N. A. Adrova, M. I. Bessonov, L. A. Lauis and A. P.

Rudakov, Polyimides, Technomic Pub. Co., Inc., Stamford, CT, 1970].

Wholly aromatic polyimides are known for their exceptional

25 thermal, thermooxidative and chemical resistance, but are generally

difficult to process as structural adhesives or composite matrices.

Several polyimides such as Kapton ® (DuPont), PI-2080 (Dow Chemical,

licensed to Lenzing), XU-218 TM (Ciba-Geigy), Ultem ® (General Electric)

and LaRCTM-TPI (Mitsui Toatsu) are commercially available and used as

30 fibers, films, moldings, adhesives or composite matrices.

The incorporation of ethynyl groups in polyimides has been

reported in the literature, typically as terminal groups to yield acetyleneterminated imide oligomers (ATI). Thermid-600 TM, an oligoimide with
LAR 15175-1 -3- PATENT APPLICATION

acetylene end groups was first developed at the Hughes Aircraft Co. [N.

Bilow, A. L. Landis and L. J. Miller, U.S. Patent 3,845,018 (1974); A.

L. Landis, N. Bilow, R. H. Boschan, R. E. Lawrence and T. J. Aponyi,

Polym. Prepr., 15, 537(1974); N. Bilow and A. L. Landis, Natl. SAMPE

5 Tech. Conf. Ser., 8, 94(1976)]. Several reviews on polyimides or

acetylene-terminated prepolymers are published and discuss other

acetylene containing polyimides [P. M. Hergenrother, in (H. Mark, ed.)

Encyclopedia of Polymer Science and Engineering, 2nd. ed., vol. 1, John

Wiley and Sons, Inc., New York, 61(1985); P. M. Hergenrother in (H.

10 Mark, ed.) Encyclopedia of Polymer Science and Engineering, 2nd. ed.,

vol. 7, John Wiley and Sons, Inc., New York, 639(1987); T. Takekoshi,

in (C. G. Overberger, ed.) Advances in Polymer Science, 2(1990)].

Polyimides containing pendent ethynyl groups have been reported but

one reference contains an abstract only with no experimental details or

15 polymer properties [F. W. Harris, S. M. Padaki and S. Varaprath, Polym.

Prepr., 21(1), 3(1980)]. Other disclosures on polyimides containing

pendent ethynyl groups contain detailed experimental information and

polymer properties [B. J. Jensen, P. M. Hergenrother and G. Nwokogu,

Polym. Prepr., 33(1), 914 (1992) and B. J. Jensen, P. M. Hergenrother

20 . and G. Nwokogu, Polymer, 34(3), 630, (1993)].

Summary of the Invention

The primary object of the present invention is to provide a series

25 of phenylethynyl-terminated imide oligomers of various molecular weights

that can be thermally cured to provide materials that are crosslinked,

insoluble in common organic solvents and have excellent high

temperature mechanical properties. Another object is to provide novel

amino phenylethynyl compounds that can be used to terminate

30 oligomers.

According to the present invention, the foregoing and additional

objects were obtained by synthesizing phenylethynyl-terminated imide

oligomers with different polymer backbones and different molecular

weights. After curing 1 hour at 350°C, the resulting polymers were

35 crosslinked and insoluble in common organic solvents. Molecular
LAR 15175-1 -4- PATENT APPLICATION

weights prepared include 3000, 6000 and 9000 g/mole. However, this

should not be viewed as a limitation since essentially any molecular

weight from =500 to _20000 g/mole is easily prepared by adjusting the

monomer stoichiometry. A modified Carothers equation, Dp = (1 + r) /

5 (1 - r) where r -- monomer ratio and Dp = degree of polymerization,

provides a means to calculate the monomer ratio necessary to produce

the desired molecular weight. The general synthetic procedure is shown

in the drawing. Data for theoretical number average molecular weights

(Mn), inherent viscosities (Tlin h) and glass transition temperatures of

10 uncured and cured polymers are included in Table 1. Data for the

thermal stability of the cured polymer in air and nitrogen and the thin film

properties are included in Table 2. Data for the titanium to titanium

adhesive properties are included in Table 3. The phenylethynylterminated imide oligomers of the present invention are eminently

15 suitable as adhesives, composite matrices, moldings, films and coatings.

Two significant advantages of phenylethynyl-terminated imide

oligomers compared to linear polyimides are better compression

moldability (more flow, better consolidation under less pressure) and the

ability to react forming a structure containing some crosslinks which

20 typically increases the solvent resistance, glass transition temperature,

and modulus. These properties are important for aerospace applications

as films, moldings, adhesives and composites.

The advantage of phenylethynyl-terminated imide oligomers

compared to polyimides containing pendent ethynyl or phenylethynyl

25 groups is that the phenylethynyl-terminated imide oligomers have low to

moderate molecular weights and therefore have lower melt viscosity for

easier processing into moldings, composites and adhesive bonds.

The advantage of phenylethynyl-terminated imide oligomers

compared to ethynyl-terminated polyimides is the higher reaction

30 temperature of the phenylethynyl group compared to the ethynyl group.

The phenylethynyl group begins to react at -350°C (beginning of the

exotherm in the DSC trace when run at 20°C/min) compared to "200°C

for the ethynyl group. This higher reaction temperature provides a larger

window to melt process these oligomers whereas ethynyl-terminated
LAR 15175-1 -5- PATENT APPLICATION

imide oligomers begin to react and, therefore are either not melt

processable or have a very small window to melt process.

5

Brief Description of the Drawing

For a more complete understanding of the present invention,

including its primary objects and attending benefits reference

10 should be made to the Description of the Preferred Embodiments,

which is set forth in detail below. This description should be read

together with the accompanying drawing, wherein the single

drawing figure is an equation showing the general synthetic

scheme for the preparation of phenylethynyl terminated imide

15 oligomers according to the present invention.

Description of the Preferred Embodiments

The approach according to the present invention was to

20 provide phenylethynyl-terminated polyimides by employing any of

four novel phenylethynyl amine compounds to endcap imide

oligomers. By adjusting the monomer stoichiometry, the molecular

weight of the resulting phenylethynyl-terminated polyimide could

be controlled. The four phenylethynyl amine compounds are 3 and

25 4-aminophenoxy-4'-phenylethynylbenzophenone, and 3 and 4-

amino-4'-phenylethynylbenzophenone, which have the following

structures, respectively:

30

0 0
5

LAR 1 5175-1 -6- PATENT APPLICATION

The phenylethynyl group is the functionality which reacts at

elevated temperatures, while the amine group allows the

compound to be incorporated into any system which reacts with

an amine. Any compound having the following general structural

formula can also be used as an endcapping agent

where X is nil or a meta or para substituted phenoxy group and Y is an

activating group consisting of C(CF3) 2, CO, or SO 2.

10 The phenylethynyl group has two important advantages over

the ethynyl group. These are stability towards conditions of

aromatic nucleophilic displacement reactions and stability at

moderate temperatures (i.e. 150 - 250°C). For example, when 4-

phenylethynyl-4'-fluorobenzophenone was treated with a slight

15 excess of 3 or 4-aminophenol in the presence of an alkali metal

base such as potassium carbonate in a polar aprotic solvent such

as N,N-dimethylacetamide (DMAc) at 143°C, 3 or 4-

aminophenoxy-4'-phenylethynylbenzophenone was afforded in

nearly quantitative yield. However, several attempts to make the

20 3-aminophenoxy-4'-ethynylbenzophenone from the 4-ethynyl-4'-

fluorobenzophenone under similar reaction conditions afforded a

mixture of products. In addition, imide model compounds of the

phenylethynyl endcapper react at a moderate to fast rate in air at

300 to 350°C whereas analogous model compounds containing

25 the ethynyl group react at a moderate to fast rate in air at 200 to

250°C. Phenylethynyl containing imide model compounds are

reasonably stable at 200°C (see Example 6) whereasthynyl

containing imide model compounds react at 200°C.

When an imide oligomer terminated with these activated

30 phenylethynyl endcappers has been cured in a steel mold for 1

hour at 200 psi and 350°C, the resulting glass transition

temperatures (Tg) are 15 to 20°C higher than those of the cured

imide oligomer terminated with nonactivated phenylethynyl

endcappers. (See Example 7 below and the accompanying Table).
LAR 15175-1 -7- PATENT APPLICATION

Cured imide oligomers terminated with the activated phenylethynyl

endcappers offered higher use temperatures than that of cured

imide oligomers from nonactivated phenylethynyl endcappers.

5 Example 1

Synthesis of Bromo Benzophenones

Synthesis of 4-brom0-3'-nitrobenzophenone

10 In a 250 mL flask equipped with a nitrogen inlet, overhead stirring

assembly, and reflux condenser were placed 3-nitrobenzoyl chloride (28

g, 0.15 mol), bromobenzene (130 g, 0.83 mol), and aluminum chloride

(22 g, 0.16 mol). The mixture was heated for 3 h at 100°C, then cooled

to room temperature and stirred for an additional 16 h. The mixture was

15 poured into 1 L of acidic (HCI) ice water, and the organics were

extracted using methylene chloride, dried over magnesium sulfate, and

the solvents were removed under reduced pressure to yield a yellow

powder. Recrystallization from acetone afforded 42.1 g (90% yield) of

white crystals: m.p. 104-105°C.

20 AnalCalcdforC13H8NO3Br: %C=51.01%H=2.63 %N=4.58

%Br=26.01

Found: %C=50.08 %H=2.82 %N=4.45 %Br=25.81

25

Synthesis of 4-bromo-4'-nitrobenzophenone

In a 250 mL flask equipped with a nitrogen inlet, overhead stirring

assembly, and reflux condenser were placed 4-nitrobenzoyl chloride

(22.6 g, 0.122 mol), bromobenzene (100 g, 0.63 mol), and aluminum

chloride (17.3 g, 0.13 mol). The mixture was heated for 3 h at 100°C,

30 then cooled to room temperature and stirred for an additional 16 h. The

mixture was poured into 1 L of acidic (HCI) ice water, and the organics

were extracted using methylene chloride, dried over magnesium sulfate,

and the solvents were removed under reduced pressure to yield a yellow

powder. Recrystallization from acetone afforded 29.2 g (85% yield) of

35 yellow crystals: m.p. 123-124°C, (Lit. 122°C) .
LAR 15175-1 -8- PATENT APPLICATION

0 0

AICI3

OL;N-I --CI )-Br > 02N - -Br

5

Example 2

Synthesis of Phenylethynylbenzophenones

10

Synthesis of 4-fluoro-4'-phenylethynylbenzophenone

In a 250 mL flask equipped with a nitrogen inlet, overhead

stirring assembly, and reflux condenser were placed fluorobenzene

(117 g, 1.2 mol) and 4-bromobenzoyl chloride (39.8 g, 0.181

mol). The mixture was cooled to O°C and aluminum chloride (27

15 g, 0.20 mol) was added. The mixture was stirred for 15 minutes

at 23°C, followed by heating to reflux for 4 h. The reaction was

then cooled to 23°C and stirred for 16 h. The resulting slurry was

poured into 2 L of acidic (HCI) water. The organics were extracted

with methylene chloride, and dried over magnesium sulfate. The

20 slurry was filtered and the methylene chloride was removed under

reduced pressure to yield an off white powder. Recrystallization

from ethanol afforded 43.3 g (86%) of 4-bromo-4'-

fluorobenzophenone as white crystals: m.p. 106-107°C, (Lit.

107-108°C).

25 In a 500 mL flask equipped with nitrogen inlet, overhead

stirring assembly, and reflux condenser were placed 4-bromo-4'-

fluorobenzophenone (30.0 g, 0.107 mol), phenylacetylene (11.0 g,

0.107 mol), triphenylphosphine (0.2 g), copper (I) iodide (0.1 g),

bis(triphenylphosphine)pallidium (11) chloride (0.1 g), and 450 mL

30 of triethylamine. The mixture was heated to reflux for 4 h and

then cooled to 23°C and stirred for an additional 16 h. The

mixture was poured into acidic (HCI) water and the precipitate was
5

LAR 15175-1 -9- PATENT APPLICATION

collected by filtration. Recrystallization from acetone yielded 23 g

(75%) of white crystals: m.p. 150-151 °C. IR (KBr): 2211 cm-1

(C-C); 1650 cm-1 (C=O); 1225 cm-1 (arylfluorine): 1H-NMR

(CDCI3): 7.8-6.8 ppm (m H aromatic).

AnalCalcdforC21H13FO: %C=83.99 %H=4.36

%F=6.83

Found: %C =83.98 %H =4.38 %F=6.16

10

15

20

25

Synthesis of 3-nitro-4'-phenylethynylbenzophenone

In a 250 mL flask equipped with a nitrogen inlet and reflux

condenser were placed 4-bromo-3'-nitrobenzophenone (15.31 g, 0.050

mol), phenylacetylene (5.62 g, 0.055 mol), triphenylphosphine (0.100 g),

bis(triphenylphosphine)pallidium (11) chloride (0.050 g), and 100 mL of

triethylamine. The mixture was heated to 50-60°C. Copper (I) iodide

(0.050 g), and additional 50 mL of triethylamine were added. The

reaction was heated to reflux for 2 h, then cooled to room temperature.

The resulting precipitate was collected by filtration, washed with acidic

(HCI) water, and dried at 100°C. Recrystallization from 1-butanol

afforded 13.73 g (85% yield) of white crystals: m.p. 185-186°C. IR

(KBr) 3086 cm-1 (aromatic); 2209 cm-1 (C-C); 1654, 1612 cm-1 (C =O);

and 1601 cm-1 (aromatic C-H).

AnalCalcdforC21H13NO3: %C=77.05 %H=4.00 %N=4.28

Found: %C=76.54 %H=4.26 %N=4.02

Synthesis of 4-nitro-4'-phenylethynylbenzophenone

30

In a 250 mL flask equipped with a nitrogen inlet and reflux

condenser were placed 4-bromo-4'-nitrobenzophenone (19.3 g, 0.063

mol), phenylacetylene (6.5 g, 0.063 mol), triphenylphosphine (0.15 g),

bis(triphenylphosphine)pallidium (11) chloride (0.08 g), copper (I) iodide

(0.08 g), and 100 mL of triethylamine. The mixture was heated to 65°C

for 16 h, then cooled to room temperature. The resulting mixture was

poured into acidic (HCI) water, the precipitate was collected by filtration
5

LAR 15175-1 -10- PATENT APPLICATION

and dried in vacuo at 110°C. Recrystallization from toluene afforded 9.5

g (47% yield) of yellow-white crystals: m.p. 193-195°C. IR (KBr) 3086

cm-1 (aromatic); 2212 cm-1 (C-C); 1656 cm-1 (C =O); and 1602 cm-1

(aromatic C-H). Mass Spec. mie (relative intensity) : M +, 327.1 (53%);

FW = 327.34 g/mol.

AnalCalcdforC21H13NO3: %C=77.05 %H=4.00 %N=4.28

Found: %C= 76.84 %H= 3.94 %N=3.81.

PdCI2(P_3)2

0 Cul 0

X -_ I_1-_Br ! t HC-_ -_ _ _J -I_1"-_C--_C

NEt3 II X

X-F, NO 2

©

10 Example 3

Synthesis of Phenylethynylamino Endcappers

Synthesis of 4-(3-aminophenoxy)-4'-phenylethynylbenzophenone (3-

APEB)

15 In a 500 mL flask equipped with nitrogen inlet, overhead stirring

assembly, Dean-Stark trap, and reflux condenser were placed 3-

aminophenol (18.5 g, O. 17 mol), 4-phenylethynyl-4'-fluorobenzophenone

(43.2 g, 0.14 mol), potassium carbonate (22 g, 0.16 mol), toluene (30

mL), and DMAc (200 mL). The mixture was heated to 142°C for 8 h,

20 then cooled to room temperature. The reaction mixture was poured into

water and the resulting light yellow powder was collected by filtration.

Recrystallization from water/acetone (50/50) (v) and sodium dithionite

(0.5 g) afforded 51.8 g (95% yield) of the desired product: m.p. 137-

139°C. IR (KBr); 3414 and 3342 cm-1 (NH2); 3040, 1596, and 1499

25 cm-1 (aromatic C-H); 2216 cm-1 (C-C), and 1646 cm-1 (C=O): Mass

Spec. m/e (relative intensity) : M +, 389.4 (100); FW = 389.44 g/mol.

AnalCalcdforC27H19NO2: %C=83.28 %H=4.92 %N=3.60

Found: %C=82.80 %H=4.86 %N=3.00
LAR 15175-1 -11- PATENT APPLICATION

4-(4-Aminophenoxy)-4'-phenylethynylbenzophenone (4-APEB)

In a 250 mL flask equipped with nitrogen inlet, overhead stirring

assembly, Dean-Stark trap, and reflux condenser were placed 4-

5 aminophenol (5.46 g, 0.05 tool), 4-phenylethynyl-4'-fluorobenzophenone

(15.02 g, 0.05 mol), potassium carbonate (7.6 g, 0.055 tool), toluene

(20 mL), and DMAc (45 mL). The mixture was heated to 150°C for 2 h,

then cooled to room temperature. The reaction mixture was poured into

water and the resulting light yellow powder was collected by filtration.

10 Recrystallization from toluene afforded the desired product in 85% yield:

m.p. 151-153°C. IR(KBr); 3382 and 3314cm-1 (NH2); 3049, 1599,

and 1509 cm-1 (aromatic C-H); 2217 cm-1 (C-C); and 1645 cm-1

(C=O): Mass Spec. m/e (relative intensity) : M+, 389.4 (100); FW =

389.44 g/mol.

15 AnalCalcdforC27H19N02: %C=83.28 %H=4.92 %N=3.60

Found: %C=81.50 %H=4.98 %N=3.39

0

O

K2CO3 O_c c

DMAc/'rol A H2N-t_0 -@

20 Synthesis of 3-amino-4'-phenylethynylbenzophenone

In a 500 mL flask equipped with a nitrogen inlet, thermometer,

addition funnel, and reflux condenser were placed 3-nitro-4'-

phenylethynylbenzophenone (8.18 g, 0.0250 tool), ammonium chloride

25 (5.35 g, 0.10 mol) and ethanol (60 mL). A solution of sodium sulfide

nonahydrate (24.02 g, 0.10 mol) and water (60 mL) was added over a

45 minute period. The mixture was heated to 70°C for 4 h. Water (120

mL) was added and the mixture was allowed to cool to room

temperature. The precipitated solid was collected by filtration, washed in

30 water and allowed to dry. Recrystallization from ethanol afforded 5.09 g

(69% yield) of a pale yellow solid: m.p. 140-142°C. IR (KBr); 3463
5

LAR 15175-1 -12- PATENT APPLICATION

3356 and 3208 cm-1 (NH2); 2217 cm-1 (C=C); and 1646 cm-1 (C=O)"

1H-NMR (CDCI 3) • 3.63 (s, 2H amine); 6.7 - 8.0 (m, 13H, aromatic).

Mass Spec. m/e (relative intensity) • M +, 297 (74); FW = 297.36 g/tool.

AnalCalcdforC21H15NO: %C=84.82 %H=5.08 %N=4.71

Found: %C=84.99 %H=5.12 %N=4.52

Synthesis of 4-amino-4'-phenylethynylbenzophenone

10 In a 500 mL flask equipped with a nitrogen inlet and reflux

condenser were placed sodium sulfide nonahydrate (16.81 g, 0.070

mol), 4-nitro-4'-phenylethynylbenzophenone (9.82 g, 0.030 mol),

ammonium chloride (3.74 g, 0.070 mol), 200 mL of ethanol, and 20 mL

of water. The mixture was heated to reflux for 4 h, then allowed to cool

15 to room temperature. The solvent was removed under reduced pressure,

and the resulting solid was washed in water, collected by filtration, and

dried at 100°C. Recrystallization from ethanol afforded 5.41 g (61%

yield) of a pale yellow solid: m.p. 195-196.5°C. IR (KBr) 3422, 3340,

and 3224 cm-1 (NH2); 2216 cm-1 (C-C); 1637 cm-1 (C=O). 1H-NMR

20 (DMF-d 7) : 6.28 (s, 2H amine); 6.65 - 7.90 (m, 13H, aromatic). Mass

Spec. m/e (relative intensity) : M +, 297.2 (47); FW = 297.36 g/mol.

AnalCalcdforC21H15NO: %C=84.82 %H=5.08 %N=4.71

Found: %C=84.60 %H=5.26 %N=4.60

25

0

II

NH Cl 0

Na2S'9H20 4

--0 EtOH/H20 H_ -_

-0
LAR 15175-1 -13- PATENT APPLICATION

Example 4

Synthesis of Imide Model Compounds

5

Synthesis of 4-phenylethynylbenzoyl-4'-phenoxy-3"-phenylphthalimide

In a 200 mL flask equipped with a reflux condenser were placed

phthalic anhydride (1.33 g, 8.9 mmol), 3-APEB (3.50 g, 8.9 mmol), and

acetic acid (100 mL). The solution was stirred for 1.5 h at 23°C and

heated to reflux for 3 h. The solution was poured into 2 L of water, the

10 precipitate was collected by filtration, washed in warm ethanol, and dried

at 120°C in vacuo to afford 4.4g (95% yield) of white powder: m.p.

167.5-169°C. IR (KBr); 3040-3010 and 1602 cm-1 (aromatic C-H),

2209 cm-1 (C-C), 1771 and 1727 cm-1 (imide), and 1657 cm-1 (C=O).

Anal Calcd for C35H21NO 4 : %C=80.91 %H=4.07 %N=2.70

15 Found : %C=79.72 %H=3.99 %N=2.57

Synthesis of 4-phenylethynylbenzoyl-4'-phenoxy-4"-phenylphthalimide

In a 50 mL flask equipped with a reflux condenser were placed

phthalic anhydride (0.76 g, 5.13 mmol), 4-APEB (2.00 g, 5.13 mmol),

20 and acetic acid (30 mL). The solution was heated to reflux for 16 h.

The solution was poured into 1 L of water, and the precipitate was

collected by filtration, washed in boiling methanol, and dried at 100°C in

vacuo to afford 2.5 g (95% yield) of light tan powder: visual m.p. 202-

205°C. IR (KBr); 3050-3020 and 1600 cm-1 (aromatic C-H), 2217 cm-1

25 (C-C), 1772 and 1714 cm-1 (imide), and 1648 cm-1 (C=O).

Anal Calcd for C35H21NO4 • %C=80.91 %H=4.07 %N=2.70

Found" %C = 78.88 %H =4.06 %N =2.31

30

0

_lAcOH
LAR 15175-1 -14- PATENT APPLICATION

Synthesis of 4-phenylethynylbenzoyl-3'-phenylphthalimide

5

10

15

In a 100 mL flask equipped with a reflux condenser were placed 3-

amino-4'-phenylethynylbenzophenone (2.97 g, 0.010 mol), phthalic

anhydride (1.48 g, 0.010 mol), and glacial acetic acid (50 mL). The

mixture was heated to reflux for 16 h, then cooled to room temperature.

The resulting precipitate was collected by filtration, washed with acetic

acid and water and dried at 100°C. Recrystallization from 1-butanol

afforded 3.50g (82% yield) of a white solid: m.p. 195-195.5°C. IR (KBr)

2214 cm-1 (C-C), 1727 cm-1 (imide C=O), and 1654 cm-1 (C=O).

Mass Spec. m/e (relative intensity) : M +, 427.4 (6); FW = 427.46

g/mol.

Anal Calcd for C29H17NO3: %C = 81.49 %H=4.01 %N=3.28

Found: %C=81.38 %H=3.93 %N=3.10

Synthesis of 4-phenylethynylbenzoyl-4'-phenylphthalimide

In a 100 mL flask equipped with a reflux condenser were placed 4-

amino-4'-phenylethynylbenzophenone (2.97 g, 0.010 mol), phthalic

20 anhydride (1.48 g, 0.010 mol), and 50 mL of glacial acetic acid. The

mixture was heated to reflux for 16 h, then cooled to room temperature.

The resulting solid was collected by filtration and dried at 100°C.

Recrystallization from 1-butanol afforded 3.05 g (71.4% yield) of white

-1

crystals: m.p. 204 - 205°C. IR (KBr) 2216 cm-1 (C-C), 1774, 1718 cm

25 (imide C=O), and 1654 cm-1 (C=O). Mass Spec. m/e (relative intensity)

: M +, 427.4 (6); FW = 427.46 g/mol.

AnalCalcdforC29H17NO3: %C=81.49 %H=4.01 %N=3.28

Found: %C=81.12 %H=3.82 %N=2.89

30
: . J

LAR 15175-1 -15-

o

AcOH

0

PATENT APPLICATION

Example 5

5 4-Phenylethynylbenzoyl-4'-phenoxy-3"-phenylphthalimide, 4-

phenylethynylbenzoyl-4'-phenoxy-4"-phenylphthalimide, and 4-

phenylethynylbenzoyl-4'-phenylphthalimide were individually placed in a

DSC cell and heated at a rate of 10°C/min to 450°C. The model

compounds displayed melting point maxima of 172, 209 and 208°C with

10 a melting enthalpies of 101, 109, and 107 Jig respectively. The

exothermic onsets occurred at 354, 347, and 319°C with maximum

onsets at 415, 402, and 399°C and curing enthalpies of 248, 287, and

408 J/g respectively. These compounds were also held at 350°C for 1

h. The resulting DSC thermograms of these thermally treated

15 compounds displayed an absence of both melting points and exothermic

peaks.

Example 6

20 4-Phenylethynylbenzoyl-4'-phenoxy-3"-phenylphthalimide, 4-

phenylethynyl-benzoyl-4'-phenoxy-4"-phenylphthalimide, and 4-

phenylethynylbenzoyl-4'-phenylphthalimide were individually placed in a

DSC cell and held at 200°C for 20 h. The melting enthalpies of these

compounds were 90.7, 73.2, and 95.7 Jig respectively indicating that

25 89%, 68%, and 89% of the starting material remained intact.
LAR 15175-1 -16- PATENT APPLICATION

Example 7

Synthesis of a 9000 g/tool phenylethynyl-terminated imide oligomer

In a 250 mL flask equipped with a nitrogen inlet, overhead stirring

5 assembly, and reflux condenser were placed 3,4'-ODA (3.7992 g, ).019

mol), ODPA (6.2045 g, 0.200 mol), and the appropriate endcapper

(0.8007 mol), m-cresol (54 g), and isoquinoline (0.2 g). The solution

was stirred at 23°C for 16 h, and heated to reflux for 3.5 h. The

reaction was cooled to 23°C and poured into stirring methanol. The

10 white precipitate was collected by filtration, extracted with methanol for

48 h and dried in vacuo at 180°C for 10 h to yield 9.2 g (98%) of white

powder.

15

Thermal Properties of a 9000 g/mol Imide Oligomer Synthesized

from ODPA and 3,4'-ODA Using Several Phenylethynyl Endcaps

Endcap

0

0

qinh

(dL/g)"

0.35

0.41

0.36

0.37

Tg (°C)

Uncured

218

226

220

213

Tg (°C)

b

Cured

243

242

228

223

a. Measured in m-cresol at 25°C using a conc. of 0.5 g/dL.

b. Cured in a mold at 350°C for 1 hour at 200 psi.

20 The general reaction scheme for the phenylethynyl-terminated

imide oligomers is shown in the Drawing where n is an integer from 1-

100 repeat units. The solvent can be N, N-dimethylacetamide (DMAc),

N-methylpyrrolidinone (NMP), N, N-dimethylformamide (DMF) or
LAR 15175-1 -17- PATENT APPLICATION

m-cresol. Ar' can be as simple as 1,2,4,5-tetrasubstituted benzene, or it

may be a bis-4-(o-diphenylene) having the general structure

5 where X = nil, O, S, C=O, SO 2, CH 2, C(CH3)2,C(CF3)2,

0 0

-_-@_- etc., and mixtures thereof.

0

-L-,_ o

10

Ar in the Drawing is selected from a group of radicals consisting of

-O O -

wherein Y = nil, O, S, C=O, SO 2, CH 2, C(CH3) 2, C(CF3)2, etc., and

mixtures thereof.

Phenylethynyl-terminated imide oligomers with a wide range of

15 molecular weights (_500 to _20,000 g/mole) are readily prepared by

offsetting the ratio of one monomer relative to the other by a calculated

amount and adding an appropriate amount of either 3- or 4-

aminophenoxy-4'-phenylethynylbenzophenone or 3- or 4-amino-4'-

phenylethynylbenzophenone. Prior to curing, low molecular weight

20 polymers have low melt viscosity and are readily processed into

moldings, composites and adhesive bonds. When cured, different

molecular weight polymers display different properties. For example, low

molecular weight phenylethynyl-terminated imide oligomers provide a

higher crosslink density than higher molecular weight phenylethynyl25 terminated imide oligomers. Materials containing high crosslink density
5

LAR 1 5175-1 -18- PATENT APPLICATION

normally produce better solvent resistance, higher modulus, better high

temperature properties and lower toughness than those containing low

crosslink density. Therefore, the polymers can be designed with the

proper combination of properties for the desired application by controlling

the molecular weight. Specific examples follow.

Example 8

The following example illustrates the synthesis of a phenylethynyl10 terminated imide oligomer with theoretical number average molecular

weight of 3000 g/mole. 3,4'-Oxydianiline (ODA) (4.268 mmole, 0.8546

g), 4,4'-oxydiphthalic dianhydride (ODPA) (5.000 mmole, 1.5511 g), 4-

(4-aminophenoxy)-4'-phenylethynylbenzophenone (4-APEB) (1.494

mmole, 0.5819 g, 2% excess), m-cresol (14 g), and isoquinoline (0.2 g)

15 were added to a 100 mL three neck flask equipped with a mechanical

stirrer, condenser and nitrogen inlet. The reaction was stirred at 25°C

for 16 h followed by heating at reflux (_195°C) for 4 h. After cooling,

the reaction was poured into methanol, washed in boiling methanol and

dried at 110°C for 72 h to afford an off-white solid in > 95% yield. The

20 01in h ) resulting phenylethynyl-terminated polyimide had an inherent

viscosity of 0.20 dL/g in m-cresol at 25°C. Additional properties for this

polymer are listed in Tables 1, 2 and 3.
i'-

O1

',,4

O1

!

TABLE 1. CHARACTERIZATION OF 3,4'-ODA/ODPA PHENYLETHYNYL-TERMINATED

IMIDE OLIGOMERS AND THEIR CURED POLYMERS

Theoretical

Mn, g/mole

3000

3000

6000

6000

9000

9000

Endcapper

3-APEB

4-APEB

3-APEB

4-APEB

3-APEB

4-APEB

Polyimide

_.!nh, dL/_g

DSC Tg, °C

Initiala Final b

173

195

208

2O8

220

222

0.12

0.20

0.22

0.22

0.36

0.41

233

246

246

245

249

250

aThermally imidized in m-cresol at ~195°C for 4h with isoquinoline catalyst

bArter curing lh each at 100, 225 and 3.5.0°C_

!

.,..&

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cN

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p!cIq lou tUJOl le qBn01 tUlB •

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£:61.

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0006

0006

0009

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TABLE 3 FABRICATION CONDITIONS AND ADHESIVE PROPERTIES

OF CURED 3APEB TERMINATED 3,4' ODA/ODPA IMIDE OLIGOMERS

i-"

:1;.

O1

,.,j

O1

!

,..•},

Theoretical

Mn cj/mo!e "

3000

Molding

Pressure; psi

15

n

Exposure

Condilions

_ _ . - _

none

Tes!

T emoeralure; 09

23

3000 25 none 23 5270

' - ,...i • n •

300.0 50 none 23 5270

300.0 50 48h soak a 23

30O0

none

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50

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177

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4730

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3860

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9009 25 none 23 5460

9000 50 none 23 7400

9000 §0 48h soak a 23 6370

. , .,, . . . -

9000 §0 non? !77 3900

9099 50 3000h!177oc 177 3890

aChevron HyJ.e! IV hydraulic fluid

I

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LAR 15175-1 -22- PATENT APPLICATION

Example 9

The following example illustrates the synthesis of a phenylethynyl5 terminated imide oligomer with theoretical number average molecular

weight of 6000 g/mole. 3,4'-Oxydianiline (ODA) (4.619 mmole, 0.9250

g), 4,4'-oxydiphthalic dianhydride (ODPA) (5.000 mmole, 1.5511 g), 4-

(4-aminophenoxy)-4'-phenylethynylbenzophenone (4-APEB) (0.7762

mmole, 0.3023 g, 2% excess), m-cresol (14 g), and isoquinoline (0.2 g)

10 were added to a 100 mL three neck flask equipped with a mechanical

stirrer, condenser and nitrogen inlet. The reaction was stirred at 25°C

for 16 h by heating at reflux (=195°C) for 4 h. After cooling, the

reaction was poured into methanol, washed in boiling methanol and dried

at 110°C for 72 h to afford an off-white solid in >95% yield. The

15 resulting phenylethynyl-terminated polyimide had an inherent viscosity

(Tlin h) of 0.22 dL/g in m-cresol at 25°C. Additional properties for this

polymer are listed in Tables 1, 2 and 3.

20

Example 10

The following example illustrates the synthesis of a phenylethynylterminated imide oligomer with theoretical number average molecular

weight of 9000 g/mole. 3,4'-Oxydianiline (ODA) (4.743 mmole, 0.9498

g), 4,4'-oxydiphthalic dianhydride (ODPA) (5.000 mmole, 1.5511 g), 4-

25 (4-aminophenoxy)-4'-phenylethynylbenzophenone (4-APEB) (0.5243

mmole, 0.2042 g, 2% excess), m-cresol (14 g), and isoquinoline (0.2 g)

were added to a 100 mL three neck flask equipped with a mechanical

stirrer, condenser and nitrogen inlet. The reaction was stirred at 25°C

for 16 h followed by heating at reflux (=195°C) for 4 h. After cooling,

30 the reaction was poured into methanol, washed in boiling methanol and

dried at 110°C for 72 h to afford an off-white solid in > 95% yield. The

resulting phenylethynyl-terminated polyimide had Tlinh of 0.41 dL/g in

m-cresol at 25°C. A film cast from m-cresol solution of this oligomer

and cured lh at 350°C was tough and finger nail creasible. The film

35 was completely insoluble and did not swell when soaked for 48h in
LAR 15175-1 -23- PATENT APPLICATION

DMAc and completely insoluble but swelled slightly (_5% increase in

area) when soaked for 48h in methylene chloride. Additional properties

for this polymer are listed in Tables 1, 2 and 3.

5 Example 11

The following example illustrates the synthesis of a phenylethynylterminated imide oligomer with theoretical number average molecular

weight of 3000 g/mole. 3,4'-Oxydianiline (ODA) (17.07 mmole, 3.4178

10 g), 4,4'-oxydiphthalic dianhydride (ODPA) (20.00 mmole, 6.2045 g), 4-

(3-aminophenoxy)-4'-phenylethynylbenzophenone (3-APEB) (5.864

mmole, 2.2837 g), m-cresol (55 g), and isoquinoline (0.2 g) were added

to a 100 mL three neck flask equipped with a mechanical stirrer,

condenser and nitrogen inlet. The reaction was stirred at 25°C for 16 h

15 followed by heating at reflux (_195°C) for 4 h. After cooling, the

reaction was poured into methanol, washed in boiling methanol and dried

at 110°C for 72 h to afford an off-white solid in >95% yield. The

resulting phenylethynyl-terminated polyimide had _lin h of 0.12 dL/g in

m-cresol at 25°C. Additional properties for this polymer are listed in

20 Tables 1, 2 and 3.

Example 12

The following example illustrates the synthesis of a phenylethynyl25 terminated imide oligomer with theoretical number average molecular

weight of 6000 g/mole. 3,4'-Oxydianiline (ODA) (18.48 mmole, 3.7001

g), 4,4'-oxydiphthalic dianhydride (ODPA) (20.00 mmole, 6.2045 g), 4-

(3-aminophenoxy)-4'-phenylethynylbenzophenone (3-APEB) (3.044

mmole, 1.1855 g), m-cresol (55 g), and isoquinoline (0.2 g) were added

30 to a 100 mL three neck flask equipped with a mechanical stirrer,

condenser and nitrogen inlet. The reaction was stirred at 25°C for 16 h

followed by heating at reflux (_195°C) for 4 h. After cooling, the

reaction was poured into methanol, washed in boiling methanol and dried

at 110°C for 72 h to afford an off-white solid in > 95% yield. The

35 resulting phenylethynyl-terminated polyimide had Tlin h of 0.22 dL/g in
LAR 15175-1

m-cresol at 25°C.

Tables 1, 2 and 3.

-24- PATENT APPLICATION

Additional properties for this polymer are listed in

5

Example 13

The following example illustrates the synthesis of a phenylethynylterminated imide oligomer with theoretical number average molecular

weight of 9000 g/mole. 3,4'-Oxydianiline (ODA) (18.97 mmole, 3.7992

g), 4,4'-oxydiphthalic dianhydride (ODPA) (20.00 mmole, 6.2045 g), 4-

10 (3-aminophenoxy)-4'-phenylethynylbenzophenone (3-APEB) (2.056

mmole, 0.8007 g), m-cresol (55 g), and isoquinoline (0.2 g) were added

to a 100 mL three neck flask equipped with a mechanical stirrer,

condenser and nitrogen inlet. The reaction was stirred at 25°C for 16 h

followed by heating at reflux ('195°C) for 4 h. After cooling, the

15 reaction was poured into methanol, washed in boiling methanol and dried

at 110°C for 72 h to afford an off-white solid in > 95% yield. The

resulting phenylethynyl-terminated polyimide had _lin h of 0.36 dL/g in

m-cresol at 25°C. A film cast from m___:-cresolsolution of this oligomer

and cured lh at 350°C was tough and finger nail creasible. The film

20 was completely insoluble and did not swell when soaked for 48h in

DMAc and completely insoluble but swelled slightly (_5% increase in

area) when soaked for 48h in methylene chloride. Additional properties

for this polymer are listed in Tables 1, 2 and 3. This material has been

designated LARCTM-PETI - 1.

25

Example 14

The following example illustrates the synthesis of a phenylethynylterminated imide oligomer with theoretical number average molecular

30 weight of 9000 g/mole. 3,4'-Oxydianiline (ODA) (50.00 mmole,

10.0123 g), 3,3',4,4'-benzophenone tetracarboxylic dianhydride (BTDA)

(47.37 mmole, 15.2642 g), 4-(3-aminophenoxy)-4'-

phenylethynylbenzophenone (3-APEB) (5.260 mmole, 2.0485 g),

m-cresol (155 g), and isoquinoline (2 g) were added to a 250 mL three

35 neck flask equipped with a mechanical stirrer, condenser and nitrogen
LAR 15175-1 -25- PATENT APPLICATION

inlet. The reaction was stirred at 25°C for 16 h followed by heating at

reflux ('195°C) for 4 h to form an insoluble yellow precipitate. After

cooling, the reaction was poured into methanol, washed in boiling

methanol and dried at 110°C for 72 h to afford a light yellow solid in

5 >95% yield. The resulting phenylethynyl-terminated polyimide was

insoluble in m-cresol. The initial Tg by DSC was 205°C and the oligomer

displayed a melting point (Tm) with a maximum at 384°C. The wide

angle X-ray diffraction pattern also indicated the oligomer was

crystalline. The material displayed a final Tg of 278°C and no Tm after

10 heating to 450°C and cooling directly to room temperature.

Example 15

The following example illustrates the synthesis of a phenylethynyl15 terminated imide oligomer with theoretical number average molecular

weight of 9000 g/mole. Meta-phenylenediamine (m-PDA) (34.70 mmole,

3.6845 g), isophthaloyldiphthalic anhydride (IDPA) (36.70 mmole,

15.6449 g), 4-(3-aminophenoxy)-4'-phenylethynylbenzophenone (3-

APEB) (4.00 mmole, 1.5578 g), N-methylpyrollidinone (NMP) (140 g)

20 were added to a 250 mL three neck flask equipped with a mechanical

stirrer, condenser and nitrogen inlet. The reaction was stirred at 25°C

for 16 h to form the phenylethynyl-terminated polyamide acid followed

by adding acetic acid (14 g) and heating at reflux ('130°C) for 5 h.

After cooling, the reaction was poured into water, washed in boiling

25 methanol and dried at 110°C for 72 h to afford a white solid in >95%

yield. The resulting phenylethynyl-terminated polyimide was insoluble in

NMP. The initial Tg by DSC was 245°C and a final Tg of 263°C was

measured after 1 h at 350°C.

30 Example 16

35

The following example illustrates the synthesis of a phenylethynylterminated imide oligomer with theoretical number average molecular

weight of 6000 g/mole. 3,4'-Oxydianiline (ODA) (24.974 mmole,

5.0010 g), 1,3-bis(3-aminophenoxy)benzene (APB) (2.7749 mmole,
5

10

LAR 15175-1 -26- PATENT APPLICATION

0.8112 g), 3,3',4,4'-biphenyl tetracarboxylic dianhydride (BPDA) (30.00

mmole, 8.8267 g), 4-(3-aminophenoxy)-4'-phenylethynylbenzophenone

(3-APEB) (4.5012 mmole, 1.7529 g), N-methylpyrollidinone (NMP) (65 g)

were added to a 250 mL three neck flask equipped with a mechanical

stirrer, condenser and nitrogen inlet. The reaction was stirred at 25°C

for 16 h to form the phenylethynyl-terminated polyamide acid followed

by adding toluene (40 mL) and heating at 160°C for 24 h. After cooling,

the reaction was poured into water, washed in boiling methanol and

dried at 110°C for 72 h to afford a yellow solid in > 95% yield. The

resulting phenylethynyl-terminated polyimide was insoluble in NMP. The

initial Tg by DSC was 230°C and a final Tg of 252°C was measured

after 1 h at 350°C.

15

Example 17

The following example illustrates the synthesis of a phenylethynylterminated imide cooligomer with theoretical number average molecular

weight of 9000 g/mole. 3,4'-Oxydianiline (ODA) ( 77.29 mmole, 15.478

g), 4,4'-oxydiphthalic dianhydride (ODPA) ( 36.70 mmole, 11.384 g),

20 3,3',4,4'-biphenyl tetracarboxylic dianhydride (BPDA) ( 36.70 mmole,

10.797 g), 4-(3-aminophenoxy)-4'-phenylethynylbenzophenone (3-APEB)

( 7.81 mmole, 3.041 g), N-methylpyrollidinone (NMP) ( 95 g) were added

to a 250 mL three neck flask equipped with a mechanical stirrer,

condenser and nitrogen inlet. The reaction was stirred at 25°C for 16 h

25 to form the phenylethynyl-terminated polyamide acid followed by adding

toluene (20 g) and heating at 165°C for 8 h. After cooling, the reaction

was poured into water, washed in boiling methanol and dried at 180°C

for 10 h to afford a yellow solid in >95% yield. The resulting

phenylethynyl-terminated imide oligomer had Tlin h = 0.25 dL/g in NMP at

30 25°C. The initial Tg by DSC was 227°C and a final Tg of 258°C was

measured after 1 h at 350°Co
LAR 15175-1 -27-

Example 18

PATENT APPLICATION

The following example illustrates the synthesis of a phenylethynylterminated imide oligomer with theoretical number average molecular

5 weight of 9000 g/mole. 3,4'-Oxydianiline (ODA) ( 28.46 mmole, 5.6988

g), 4,4'-oxydiphthalic dianhydride (ODPA) ( 30.00 mmole, 9.3066 g), 4-

amino-4'-phenylethynylbenzophenone ( 3.08 mmole, 0.9159 g), m-cresol

(81 mL) and isoquinoline (5 drops) were added to a 250 mL three neck

flask equipped with a mechanical stirrer, condenser and nitrogen inlet.

10 The reaction was stirred at 25°C for 16 h followed by heating at reflux

('205°C) for 4h. A film was cast from a portion of this solution and

cured lh at 350°C in air. The rest of the solution was filtered and

poured into methanol to precipitate the imide oligomer, which was

washed in boiling methanol and dried at 200°C under vacuum to afford

15 an off-white solid in >95% yield. The resulting phenylethynylterminated imide oligomer had rlin h = 0.41 dL/g in m-cresol at 25°C.

The initial Tg by DSC was 226°C and a final Tg of 235°C was measured

after 1 h at 350°C. This powder could be compression molded at

350°C under 200 psi to give a well consolidated, void free molding

20 which was tough and solvent resistant. The air cured film was tough

and creasible, with a Tg of 245°C. The film was not noticeably affected

by immersion for 48h in either methylene chloride or DMAc. At 25°C,

the tensile strength, tensile modulus and elongation at break were

18,500 psi, 424,500 psi and 53%, respectively. At 177°C, these

25 properties were 8,600 psi, 279,500 psi and 65%, respectively.

Example 19

30 The following example illustrates the synthesis of a phenylethynylterminated imide oligomer with theoretical number average molecular

weight of 9000 g/mole. This material has the same chemical

composition as that is in Example 13 and is designated LARCTM-PET-I.

3,4'-Oxydianiline (ODA) ( 42.69 mmole, 8.5432 g), 4,4'-oxydiphthalic

35 dianhydride (ODPA) ( 45.00 mmole, 13.9599 g), 3-amino-4'-
LAR 15175-1 -28- PATENT APPLICATION

phenylethynylbenzophenone ( 4.620 mmole, 1.3738 g) and Nmethylpyrollidinone (NMP) (54 mL)were added to a 250 mL three neck

flask equipped with a mechanical stirrer, condenser and nitrogen inlet.

The reaction was stirred at 25°C for 24 h. A film was cast from a

5 portion of this solution and cured lh at 350°C in air. Toluene (50 mL)

was added to the rest of the solution and water was removed by

azeotropic distillation using a Dean-Stark trap. Toluene was removed and

the mixture diluted to a concentration of 15% (w/w) by the addition NMP

(61 mL). The mixture was heated at 183-191 °C for 2h. The

10 precipitated imide oligomer/NMP mixture was poured into methanol,

collected by filtration, extracted with methanol for 48h and dried under

vacuum at 220°C to afford an off-white solid in >98% yield. The

resulting phenylethynyl-terminated imide oligomer had _lin h = 0.32 dL/g

in m-cresol at 25°C. The initial Tg by DSC was 225°C and a final Tg of

15 233°C was measured after 1 h at 350°C.

Example 20

Unoriented thin films were prepared in the following manner. NMP

20 solutions (=30% solids) of the phenylethynyl terminated amide acid

oligomers were centrifuged, the decantate doctored onto clean, dry plate

glass and dried to a tack free form in a low humidity chamber. The films

on glass were dried in flowing air at 100, 225 and 350°C for 1 h each.

Thin film tensile properties were determined according to ASTM D882.

25 LARC_-PETI-1 films gave tensile strength, tensile modulus and

elongation at break at 25°C of 17,600 psi, 425,000 psi and 42% and at

177°C of 7400 psi, 284,000 psi and 76%, respectively. The air cured

film had a Tg of 249°C. Solvent resistance was determined on stressed

(0.2 x 2 in x 0.002 in) film strips immersed in various solvents for 2

30 weeks at ambient temperature. The specimens were secured in a

circular form by multiple wraps around a standard paper clip. Films from

LARCTM-PETI-1 exhibited excellent resistance to ethylene gylcol,

methylethyl ketone, jet fuel, hydraulic fluid and toluene.
LAR 15175-1 -29-

Example 21

PATENT APPLICATION

Molded specimens were prepared in the following manner.

Powdered imide oligomers (approximately 8.5 g) were compression

5 molded in a 1.252 stainless steel mold by heating to a temperature of

350°C under 150-200 psi and holding for approximately 1 h. Miniature

compact tension specimens (0.62 in x 0.62 in x 0.375 in thick) were

machined from the moldings and subsequently tested to determine their

fracture toughness (K , critical stress intensity factor) according to

Ic

10 ASTM E399 usimg four specimens per test condition. Fracture energy

(G , critical strain energy release rate) was calculated using the

Ic

mathematical relationship, G = (K)2/E, where E is the tensile modulus

Ic Ic

of the material. LARCTM-PETI-1 moldings gave G at 25°C of 13.8 in

Ic

Ib/in 2. Other moldings ( 3 in x 3 in x 0.020 in) prepared in a stainless

15 steel mold by heating the phenylethynyl terminated imide oligomers to

350°C under approximately 200 psi for 1 h were machined into dumbell

specimens and tensile properties determined according to ASTM D882.

Tensile strength and tensile modulus at 25°C were 15,900 psi and

560,000 psi and at 150°C were 8,000 psi and 460,000, respectively.

20

Example 22

LARCTM-PETI-1 adhesive specimens were prepared in the following

manner. Adhesive tape was prepared by coating 112 E-glass (A1100

25 finish) cloth with phenylethynyl terminated amic acid (PETAA) solution in

NMP and drying at a final temperature of 250°C to a volatile content of

approximately 0.7%. Several coats were required to obtain adequate

tape thickness. Titanium (Ti-6AI-4V) with a Pasagel 107 TM surface

treatment was primed with the corresponding PETAA/NMP solution, and

30 dried at 100 and 225°C for 1 h each. Titanium (Ti-3AI-2.5V) honeycomb

0.5 in. thick with a 0.25 in. cell size was acid etched, primed with the

corresponding PETAA/NMP solution and dried at 100 and 225°C for 1 h

each.
5

10

LAR 15175-1 -30- PATENT APPLICATION

Lap shear specimans were fabricated at 350°C for 1 h under

several difference pressures. Four tensile shear specimens of each resin

were tested according to ASTM D-1002.

Honeycomb sandwich panels 12 in. x 6 in. were fabricated by

bonding titanium honeycomb to titanium face sheets using PETI adhesive

tape, and by heating at 350°C for 1 h under 50 psi. The resulting

sandwich panel was cut into 2 in. x 2 in. specimens and tested

according to ASTM C-297.

Climbing drum peel panels were fabricated using titanium sheets

12 in. x 12 in., with thickness of 0.40 in. and 0.010 in. by heating at

350°C for 1 h at 50 psi. The cured panel was cut into 1 in. wide

specimens and tested according to ASTM D-1781.
LAR 15175-1 -31-

Ti/Ti Tensile Shear Strength

Test Condition

5 23°C

23°C after 72 h water boil

23°C after 48 h soak, jet fuel

150°C

150°C after 72 h water boil

10 177°C

177°C after 72 h water boil

177°C after 5000 h at 177°C, air

15

20

PATENT APPLICATION

Test Condition

Strength, psi

7400

5350

7290

4420

3760

3900

3740

4100

Flatwise Sandwich Tensile Strength

Strength, psi

-54°C 972

23°C 856

150°C 710

177°C 609

25 Test Condition

30

Climbing Drum Peel Strength

35

Strength, in. Ib/in.

-54°C 33.4

23°C 32.9

177°C 38.8

Example 23

Composites were prepared in the following manner. Unidirectional

prepregs (tapes) were prepared by coating unsized IM-7 carbon/graphite

fiber on a tape machine with 30% NMP solutions of the PETAA of
5

10

15

LAR 15175-1 -32- PATENT APPLICATION

LARCTM-PETI. The volatile contents of the tapes varied from 7 to 12%

and were controlled by the residence time and temperature of an in-line

furnance in the tape machine. Resin content in the tapes (minus

volatiles) varied from 31 to 34%by weight. Small composites (3 in. x 6

in. x 8 to 16 plies) were fabricated in a stainless steel mold by heating to

350°C under 200 psi and holding at 350°C under 200 psi for 1 h. Larger

laminates (6 in. x 6 in. x 16 to 32 plies) were fabricated in an autoclave

by heating to 350°C under 200 psi and holding for 1 h at 350°C under

200 psi.

The composite panels were ultrasonically scanned (C-scanned) to

show no voids, cut into specimens and tested for flexural properties

according to ASTM D790, short beam shear strength according to ASTN

D2344 and compression strength according to ASTM D3410 Procedure

B.

Unidirectional IM-7 Laminate Properties of

LARCTM-PETI - 1

20

Test Temperature, °C

23

177

Flexural St, Ksi (Modulus, Msi)

271

21.7

25

23

177

Short Beam Shear St., KSl

16.2

8.0

23

Compressive St., Ksi

197
LAR 15175-1

Abstract of the Disclosure

PATENT APPLICATION

Four phenylethynyl amine compounds--3 and 4-aminophenoxy-4'-

phenylethynylbenzophenone, and 3 and 4-amino-4'-

5 phenylethynylbenzophenone--were readily prepared and were used to

endcap imide oligomers. Phenylethynyl-terminated amide acid oligomers

and phenylethynyl-terminated imide oligomers with various molecular

weights and compositions were prepared and characterized. These

oligomers were cured at 300°C to 400°C to provide crosslinked

10 polyimides with excellent solvent resistance, high strength and modulus

and good high temperature properties. Adhesive panels, composites,

films and moldings from these phenylethynyl terminated imide oligomers

gave excellent mechanical performance
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