JOURNAL OF POLYMER SCIENCE: Polymer Chemistry Edition VOL. 14, 2785-2790 (1976)

Oligomeric Polyaromatic Ether-Ketone-Sulfones with Acetylenic End Groups. X*

FRANK HUANG and C. S. MARVEL, Department of Chemistry, The University of Arizona, Tucson, Arizona 85721

Synopsis

Two new oligomeric polyaromatic ether-ketone-sulfones with acetylenic end groups have been synthesized. These acetylene-terminated oligomers are soluble in common organic solvents and can be cured under thermal conditions to give the crosslinked polymers which do not soften below 240OC. In the case of oligomer which is incorporated with terephthaloyl chloride, the cured polymer shows almost no penetration below 4OOOC. Isothermal aging studies show that the cured polymers are stable in circulating air at 3OOOC with less than 10% weight loss in 3 days.

INTRODUCTION

Thermally stable laminating resins which are low-melting and soluble in the prepolymer stage and which can be cured without giving off any volatiles has been a recent research interest. Aromatic ethers, ketones, and sulfones are known to be thermally stable. In the previous paper,' the synthesis of short-chain acetylene-terminated oligomers containing these functional groups was reported. We wish to report here on the results of two new acetylene-terminated poly- aromatic ether-ketone-sulfone oligomers which are analogous to the previously reported acetylene-terminated oligomers but cure to give much higher softening thermosets.

EXPERIMENTAL

Preparation of Bisacetyl Oligomers

To a solution of 14.6 g (80.0 mmole) of p-acetylbenzoyl chloride and 15.2 g (40.0 mmole) of 4,4'-diphenoxydiphenyl sulfone in 300 ml of freshly distilled methylene chloride was added 32.0 g (240 mmole) of anhydrous aluminum chloride. Vig- orous evolution of hydrogen chloride was observed and the reaction mixture began to reflux. The reaction mixture was maintained at the refluxing tem- perature for 1 hr. The solvent was removed by distillation, and the red-brown residue was poured into 2 liters of isopropanol. The precipitates were collected by filtration, and washed with isopropanol. The product was blended three times with 600-ml portions of distilled water and once with a 700-ml portion of iso- propanol. After drying in air, the crude product was dissolved in 200 ml of

* For part IX of this series, see Kellman and Marvel.' 2785

0 1976 by John Wiley & Sons, Inc.

2786 HUANG AND MARVEL

chloroform and reprecipitated dropwise into 1200 ml of isopropanol. Upon filtration and washing with isopropanol, 23 g (84%) of the bisacetyl oligomer (Ia) was obtained as cream-colored irregular prisms; mp 163-166OC.

The infrared spectrum (KBr) showed absorption at 3050,1675,1640,1570, 1480,1390,1350,1306,1242,1170,1152,1110,1070,1016,960,935,875,855,798, 770,758,743,700,595,560, and 510 cm-'. NMR (CDCl3) showed 6 6.90-8.30 (m , aromatic, 24) and 2.63 ppm ( S , CH3,6).

ANAL. Calcd for C ~ ~ H ~ O S O ~ : C, 70.74%; H, 4.40%. S, 4.67%. Found C, 71.28%; H, 4.42%; S,

To a solution of 4.06 g (20 mmole) of terephthaloyl chloride, 7.31 g (40 mmole) of p-acetylbenzoyl chloride and 15.3 g (40 mmole) of 4,4'-diphenoxydiphenyl sulfone in 250 ml of freshly distilled methylene chloride was added 32 g (240 mmole) of anhydrous aluminum chloride and 50 ml of freshly distilled methylene chloride. Vigorous evolution of hydrogen chloride was observed and the reaction mixture began to reflux. The reaction mixture was maintained at the refluxing temperature for 4 hr. The solvent was removed by distillation and the cara- mel-colored residue was poured into 800 ml of methanol. The precipitates were collected by filtration, blended once with 600 ml of methanol, and then blended twice with 600 ml portions of distilled water. After washing with methanol, the product was dried in a vacuum oven a 6OoC overnight. A yield of 22 g (90%) of the bisacetyl oligomer (IIa) was obtained as a cream-colored irregular prism; mp 138-145OC.

The infrared spectrum (KBr) showed absorptions at 1690,1660,1580,1490, 1315,1250,1172,1155,1110,1075,1012,955,927,870,835,790,762,748,726, 686,575,549 and 498 cm-'. NMR (CDC13) showed 6 6.80-8.20 ( m , aromatic, 44) and 2.66ppm (S,CH3,6).

5.71% residue, 2.14%.

4.39%.

ANAL. Calcd for C~~HNOI&: C, 72.40%; H, 4.08%; S, 5.22%. Found: C, 69.08%; H, 4.08%; S,

Treatment of Bisacetyl Oligomers with the Vilsmeier Reagent

To 100 ml of dimethylformamide was added dropwise 50 ml of phosphorus oxychloride at O°C over a period of 30 min. The cherry-red solution was stirred at O°C for 2 hr. To the freshly prepared reagent was added dropwise a solution of 17.1 g (25.0 mmole) of the bisacetyl oligomer (Ia) in 150 ml of dimethylform- amide over a period of 30 min. The reaction mixture was allowed to stir at room temperature for 16 hr. The resulting mixture was poured into 2000 g of ice water contain.ing 15 g of sodium acetate. The precipitates were collected by filtration, washed with isopropanol, and air-dried. The crude product was dissolved in 200 ml of chloroform and reprecipitated dropwise into 2 liters of isopropanol. The product was collected on a filter, washed with isopropanol, and dried in uucuo to give 15 g (80%) of creamy irregular prisms (Ib); mp 103-108°C.

The infrared spectrum (KBr) showed absorptions at 3050,1670,1600,1580, 1480,1400,1304,1275,1240,1166,1152,1125,1106,1074,1024,932,875,839, 796,770,718,686,585,559, and 500 cm-l. NMR (CDCl3) showed 6 10.2 (d , CHO, 2); 6.93-8.20 (n, aromatic, 24), and 6.72 ppm ( d , CH=C, 2).

ANAL. Calcd for CMH2sO&C12: C, 67.09%; H, 3.55%; S, 4.06%; C1,9.02%. Found C, 67.28%; H, 3.69%; S, 3.56%; C1,8.06%.

POLYAROMATIC ETHER-KETONE-SULFONES. X 2787

To 66 ml of dimethylformamide was added dropwise 33 ml of phosphorus oxychloride at 0°C over a period of 30 min. The cherry-red solution was allowed to stir a t 0°C for 2 hr. To the freshly prepared reagent was added dropwise a solution of 20 g (16.3 mmole) of the bisacetyl oligomer (IIa) in 100 ml of di- methylformamide over a period of 10 min. The reaction mixture was allowed to stir at room temperature for 16 hr and at 42°C for 2 hr. The resulting mixture was poured into 2 liters of ice water containing 40 g of sodium acetate trihydrate. The creamy precipitates were collected on a filter and washed with distilled water and methanol. The product was then twice blended with 600 ml portions of methanol. Upon filtration and washing with methanol, 20 g (93%) of the bis- unsaturated P-chloroaldehyde (IIb) was obtained as yellow irregular prisms; mp 200-230°C (dec.).

The infrared spectrum (KBr) showed absorptions at 3130,1650,1575,1480, 1400,1282,1245,1152,1106,1070,1006,960,922,864,830,784,758,704,682, 570,544, and 490 cm-l. NMR (CDCl3) showed 6 10.2 (d , CHO, 2), 6.90-8.20 ( m , aromatic, 44); and 6.70 ppm (d , CH=C, 2).

ANAL. Calcd for CmH~O&C12: C, 69.14%; H, 3.64% S, 4.85%; C1,5.37%. Found: C, 67.29%; H, 3.90%; S, 4.54% C1,5.40%, residue, 0.56%.

Preparation of the Acetylene-Terminated Oligomers

To a solution of 9.00 g (1.14 mmole) of the unsaturated p-chloroaldehyde (Ib) in 300 ml of dimethylformamide was added dropwise a solution of 1.40 g potas- sium hydroxide in 50 ml of 95% ethanol and 100 ml of dimethylformamide. The reaction mixture was allowed to stir a t room temperature overnight. The re- action mixture was then heated at 55-60"C for 2 hr. The resulting mixture was poured into 1000 g of ice water containing 10 ml of concentrated hydrochloric acid. The precipitated product was collected on a filter, washed with distilled water and isopropanol, and dried in air. The crude product was then dissolved in 100 ml of chloroform and reprecipitated into 1 liter of isopropanol. Upon filtration and washing with isopropanol, the product was dried in a vacuum oven to give 6.85 g (91%) of yellow irregular prisms; mp 185-200°C (dec).

The infrared spectrum (KBr) showed absorptions at 3250,3050,1650,1575, 1490,1390,1250,1174,1158,1110,1075,1014,930,870,835,790,762,730,708, 685, and 570 cm-I. NMR (CDC13) showed 6 6.80-8.30 (m, aromatic, 24) and 3.26 ppm (S, W H , 2). The inherent viscosity q i d was 0.091 in dimethylformamide (0.5 g/100 ml) at 30°C.

ANAL. Calcd for C42H2606S: C, 76.60%; H, 3.95%; S, 4.86%. Found: C, 72.00; H, 4.10%; S, 4.83%.

To a solution of 10.0 g (7.55 mmole) of the unsaturated P-chloroaldehyde (IIb) in 300 ml of dimethylformamide was added dropwise a solution of 4.30 g of po- tassium hydroxide in 50 ml of 95% ethanol and 100 ml of dimethylformamide. The reaction mixture was allowed to stir at room temperature overnight. Finally, the reaction mixture was heated to 55-60"C for 1.5 hr. The resulting mixture was poured into 2000 g of ice water containing 10 ml of concentrated hydrochloric acid. The precipitated product was collected on a filter, washed with distilled water and isopropanol, and dried in air. The product was twice washed with 600-ml portions of isopropanol in a blender. Upon filtration and washing with isopropanol, 8.4 g (93%) of the acetylene-terminated oligomer (IIc) was obtained

2788 HUANG AND MARVEL

I - Y

0 - 'p I i? % E

20-

40-

60-

8 0 -

100

Cured polymer . . . . . -- . - - _ _ _

\ \ \ \ \ \ \ \ \ \ Acetylene-terminated olignner

_ _ _ _ _ _ - - ----- - - -___ \- -

- Temp. ( O C )

I I I I I I I I 50 100 I50 200 250 300 350 400 4 1

Fig. 1. Vicat softening curve of acetylene-terminated oligomer Ic and cured polymer Ic: (-)

- *

z I e 8 $I 2 0 -

cured polymer Ic; (- -) oligomer Ic.

C u r e d polymer \ . . . 0-

\ \ \ \ \ \ \ \ \ ! \ \ \

I I I I 50 100 I SO 200 250 300 350 400 4 I

Fig. 2. Vicat softening curves of acetylene-terminated oligomer IIc and cured polymer IIc: (-) cured polymer IIc; (- -) oligomer IIc.

as yellow irregular prisms; mp 200-210°C (dec.). The infrared spectrum (KBr) showed absorptions at 3270,3040,1655,1580,1485,1400,1315,1280,1245,1170, 1152,1070,1010,922,865,830,782,756,682, and 564 cm-'. The inherent vis- cosity qinh was 0.132 in dimethylformamide (0.5 g/100 ml) at 3OOC.

ANAL. Calcd for C74He01&: C, 74.62%; H, 3.86%; S, 5.38%. Found: C, 71.97% H, 4.06% S, 4.95%.

POLYAROMATIC ETHER-KETONE-SULFONES. X 2789

Crosslinking of the Acetylene-Terminated Oligomers

All crosslinking reactions were carried out in test tubes equipped with a ni- trogen inlet and a side-outlet. An aluminum foil thimble containing about 400 mg of the acetylene-terminated oligomer was placed in the test tube under ni- trogen. The test tube was then placed in a preheated aluminum heating block at 33OOC for 24 hr. The resultant dark product was stirred in 150 ml of chloro- form for 24 hr, filtered from the solvent, washed, and vacuum-dried. About 90-100% yield of the insoluble crosslinked polymer was obtained. Samples of the crosslinked polymers were taken for elemental and infrared analysis, Vicat softening point determination, and isothermal aging studies.

The infrared spectrum (KBr) of crosslinked polymer from oligomer Ic showed absorptions at 3040,1640,1565,1480,1390,1245,1150,1005,932,860,825,675, 565,545, and 480 cm-l.

ANAL. Calcd for (C&&6S),: c , 76.60%; H, 3.95%; s, 4.86%. Found: c , 73.76% H, 3.77%; s,

The infrared spectrum (KBr) of crosslinked polymer from oligomer IIc showed absorptions at 3040,1650,1575,1480,1400,1314,1245,1150,1102,1072,1008, 920,865,827,485,742,680,545, and 485 cm-l.

s, 5.52%.

4.22%.

ANAL. Calcd for (C~~HGO&&: C, 74.62%; H, 3.86% S, 5.38%. Found: C, 72.19%; H, 3.76%;

Isothermal Aging of the Crosslinked Polymers

Isothermal aging experiments were carried out by heating the cured polymers in an oven in an atmosphere of circulating air. Isothermal aging of the polymer Ic showed 8.7% weight loss at 300OC in 3 days and 15% loss in 8 days. The cured polymer IIc showed weight loss of 5.5% at 3OOOC in 3 days and 9.8% in 8 days.

RESULTS AND DISCUSSION

The acetylene-terminated oligomers (Ic and IIc) were synthesized by Friedel-Crafts acylation of 4,4’-diphenoxydiphenyl sulfone with p-acetylbenzoyl chloride or p-acetylbenzoyl chloride and terphthaloyl chloride to give Ia and IIa, respectively, followed by the conversion of the acetyl end groups to the acetylenic functions. The conversion of an acetyl group to an acetylene group has been a known reaction for simple organic molecules,24 oligomers,l and polymer^.^ Treatment of the oligomers, Ia and IIa, with Vilsmeier reagent afforded the p- chloro unsaturated aldehydes, Ib and IIb, respectively. Final conversion of the

0

0 0 II

Ia: X = -C CH3 I b X = -CCl=CHCHO Ic: X = -C=CH

2790 HUANG AND MARVEL

0 [x~l!+~~$J-oq--~ / \ - / / / \ - 0 2

0 II

IIa: X = -CCH, I h x = -CCI=CHCHO IIc: X = -CBCH

P-chloroaldehydes to the acetylene-terminated oligomers was carried out with potassium hydroxide in 95% ethanol-dimethylformamide.

These acetylene-terminated oligomers are soluble in common organic solvents such as chloroform, dioxane, and dimethylformamide. The inherent viscosities of these oligomers, Ic and IIc, are 0.091 and 0.132, respectively.

Oligomer Ic had a softening point of 120-130OC. When this oligomer was cured at 33OOC for 24 hr, it gave an insoluble polymer which had a Vicat softening range from 280 to 29OOC as shown in Figure 1. Isothermal aging studies showed that this cured polymer lost 8.7% of its weight in 3 days at 3OOOC in circulating air. Oligomer IIc softened a t 90-100°C, and it cured at 33OOC in 24 hr to give an intractable polymer with a Vicat softening point of 240-250°C as shown in Figure 2. This cured polymer lost only 5.5% of its weight at 3OOOC in 3 days and 9.8% in 8 days. In addition, the cured polymer from oligomer IIc showed less than 20% penetration up to 4OOOC and possessed greater thermal stability than the cured polymer from oligomer Ic. The greater thermal stability can be ex- plained by the higher crosslinking density which results from the greater chain mobility in oligomer IIc. The properties of these materials are very promising for use as thermally stable laminating resins.

The authors are indebted to the U S . Army Research Office-Durham, Durham, North Carolina, ARO-D project No. 20061102B13B, Contract No. DAHC04-72-C-0024 for financial support.

References

1. R. Kellman and C. S. Marvel, J. Polym. Sci. Polym. Chem. Ed., 14,2033 (1976). 2. K. Bodendorf and P. Kloss, Angew. Chem. Intern. Ed., 2,98 (1963). 3. K. Bodendorf and R. Mayer, Chem. Ber., 98,3554 (1965). 4. James M. Watson, Macromolecules, 5,331 (1972). 5. C. Samyn and C. S. Marvel, J . Polym. Sci. Polym. Chem. Ed., 13,1095 (1975).

Received January 28,1976