UNCLASSIFIED

AD NUMBER

ADB037076

NEW LIMITATION CHANGE

TOApproved for public release, distributionunlimited

FROMDistribution authorized to U.S. Gov't.agencies only; Test and Evaluation; Jan1979. Other requests shall be referred toAir Force Matererials Laboratory,Nonmetallic materials Division, PolymerBranch, Attn: AFML/MBC, Wright-PattersonAFB, OH 45433.

AUTHORITY

AFWAL ltr, 27 Aug 1981 per DTIC Form 55

THIS PAGE IS UNCLASSIFIED

AFML-TR-78-175

SYNTHESIS OF HIGH MOLECULAR WEIGHTFLUOROALKYLARYLENESILOXANYLENE (FASIL)POLYMER

MIDWEST RESEARCH INSTITUTEKANSAS CITY, MISSOURI 64110

JANUARY 1979

TECHNICAL REPORT AFML-TR-78-175

Final Report for Period 1 August 1977 to 29 December 1978

Distribution limited to U. S. Government agencies only (test and evaluation). Other requests forthis document must be referred to the Air Force Materials Laboratory, Nonmetallic MaterialsDivision, Polymer Branch, AFML/MBP, Wright-Patterson Air Force Base, Ohio 45433.

AIR FORCE MATERIALS LABORATORY

AIR FORCE WRIGHT AERONAUTICAL LABORATORIES

AIR FORCE SYSTEMS COMMAND

WRIGHT-PATTERSON AIR FORCE BASE, OHIO 45433

NOTICE

When Government drawings, specifications, or other data are used forany purpose other than in connection with a definitely related Governmentprocurement operation, the United States Government thereby incurs no re-sponsibility nor any obligation whatsoever; and the fact that the Govern-ment may have formulated, furnished, or in any way supplied the said draw-ings, specifications, or other data, is not to be regarded by implication orotherwise as in any manner licensing the holder or any other person or cor-poration, or conveying any rights or permission to manufacture, use, or sellany patented invention that may in any way be related thereto.

This report has been reviewed by the Information Office (01) and isreleasable to the National Technical Information Service (NTIS)o At NTIS,it will be available to the general public, including foreign nations.

This technical report has been reviewed and is approved for publication.

H. Rosenberg R. L. Van Deusen, ChiefProject Scientist Polymer Branch

Nonmetallic Materials Division

J. /Kelble, ChiefNonmetallic Materials Division

"If your address has changed, if you wish to be removed from our mail-ing list, or if the addressee is no longer employed by your organizationplease notify RFP'W/Met, W-PAFB, OH 45433 to help us maintain a currentmailing list."

Copies of this report should not be returned unless return is required bysecurity considerations, contractual obligations, or notice on a specificdocument.

AIR FORCE/56780/5 April 1979 - 110

TTnr-l tq4 f PdSECURITY CLASSIFICATION OF THIS PAGE (When Data Entered)

REPORT DOCUMENTATION PAGE READ INSTRUCTIONSBEFORE COMPLETING FORM

I. REPORT NUMBER 2. GOVT ACCESSION NO. 3. RECIPIENT'S CATALOG NUMBER

AFML-TR-78-175

4. TITLE (and Subtitle) S. TYPE OF REPORT & PERIOD COVEREDTechnical Report - Final

Synthesis of High Molecular Weight August 1e r 29,197

Fluoroalkylarylenesiloxanylene (FASIL) Polymer August l,1977-December 29,197ý6. PERFORMING ORG. REPORT NUMBER

7. AUTHOR(S) 8. CONTRACT OR GRANT NUMBER(s)

Re L. Elliott F33615-77-C-5152

9. PERFORMING ORGANIZATION NAME AND ADDRESS 10. PROGRAM ELEMENT, PROJECT, TASKMidwest Research Institute AREA & WORK UNIT NUMBERS

425 Volker Boulevard

Kansas City, Missouri 64110

11. CONTROLLING OFFICE NAME AND ADDRESS 12. REPORT DATEAir Force Materials Laboratory January 1979Air Force Systems Command 13. NUMBER OF PAGES

Wright-Patterson AFB, Ohio 45433 3314. MONITORING AGENCY NAME & ADDRESS(If different from Controlling Office) 15. SECURITY CLASS. (of this report)

Unclassified

15a. DECL ASSI FICATION/DOWN GRADINGSCHEDULE

16. DISTRIBUTION STATEMENT (of this Report)

Distribution limited to U.S. Government agencies only (test and evaluation).

Other requests for this document must be referred to the Air Force MaterialsLaboratory, Nonmetallic Materials Division, Polymer Branch, AFML/MBP, Wright-Patterson AFB, Ohio 45433.

17. DISTRIBUTION STATEMENT (of the abstract entered in Block 20, if different from Report)

Same

18, SUPPLEMENTARY NOTES

19. KEY WORDS (Continue on reverse side if necessary and Identify by block number)

Fluoroalkylarylenesiloxanylene (FASIL) polymers and intermediates

Channel sealantFASIL monomers

20. ABSTRACT (Continue on reverse side If necessary and identify by block number)

The synthesis of high molecular weight FASIL polymers and the followingmonomers and intermediates is described:1e Methyl(393,3-trifluoropropyl)diethoxysilane

2. 13-Bis[ethoxymethyl(3,3,3-trifluoropropyl)silyl]benzene3. 1,3-BisEhydroxymethyl(3,3,3-trifluoropropyl)silyl]benzene4. I,3-Dichloro-I,3-dimethyl-I,3-bis(3,3,3-trifluoropropyl)disiloxane

5. I,3-Bis(dimethylamino)-I,3-dimethyl-I,3-bis(3 ,3,3-trifluoropropyl)disiloxane

DD 1 JAN73 1473 EDITION OF I NOV 65 IS OBSOLETE UnclassifiedSECURITY CLASSIFICATION OF THIS PAGE ("hen Data Entered)

FOREWORD

This report was prepared by Midwest Research Institute, 425 Volker

Boulevard, Kansas City, Missouri 64110, under USAF Contract No. F33615-77-

C-5152, "Development of Synthesis of High Molecular Weight Fluoroalkylarylene-siloxanylene (FASIL) Polymers." The work was administered under the direc-

tion of the Air Force Materials Laboratory, Air Force Systems Command,

Wright-Patterson Air Force Base, Ohio, with Dr. Harold Rosenberg (MBP) as

Project Scientist.

This technical report covers the work conducted from September 1977 to

September 1978.

The work at Midwest Research Institute, designated as Project No.

4453-L, was conducted under the supervision of Dr. Cecil C. Chappelow, Jr.,

Head, Organic and Polymer Technology Section, Environmental and Materials

Sciences Division. The work was carried out by Mr. T. J. Byerley, Mr. B. F.

Hauber, Mr. R, K. Ruckman, and Mr. R. L. Elliott who served as principalinvestigator and prepared this report.

iii

TABLE OF CONTENTS

Page

Is INTRODUCTION. .... . . . .• ....... .• • .e 1 I

II* DISCUSSION& *. . . . . • • • . . . . 2

1. Synthesis of Monomers and Intermediates .. . . 22. Initial Study of FASIL Polymer . o .* e . * . . 3

3. FASIL Polymer Sample Preparation . . . * . . . e 4

III. EXPERIMENTAL. . e e . . e . * e * e . . . . . . . . . . . 6

1. Methyl(3,3,3-trifluoropropyl)diethoxysilane. . . 6

2. I,3-Bis[ethoxymethyl(3,3,3-trifluoropropyl)-silyl]benzene .*. . . . . . . . . . . . . . . 6

3. i,3-Bis[hydroxymethyl(3,3,3-trifluoropropyl)-

silyl]benzene .e. . . . . . . . . . . . . . . 7

4. i,3-Dichloro-i,3-dimethyl-i,3-bis(3,3,3-tri-

fluoropropyl)disiloxane .*. . . . . . . . . . 8

5. i,3-Bis(dimethylamino)-i,3-dimethyl-I,3-bis-

(3,3,3-trifluoropropyl)disiloxane.. . . . . . 8

6. Initial Study of FASIL Polymer Preparation e e . 8

7. FASIL Polymer Sample Preparation ........ 10

REFERENCES . . . ........ .. . . . . . . . 12

LIST OF TABLES

Table Title Page

Effect of Solvent Amount and Monomer Stoichiometry

on FASIL Polymer Preparation. .&. . . . . . . . . . . . 9

2 Synthesis of High Molecular Weight FASIL Polymers . . . . 11

v

LIST OF ILLUSTRATIONS

Figure Title Page

1 Infrared Spectrum of Methyl(3,3,3-trifluoropropyl)diethoxysilane (Neat) .............. ........... .... .. 13

2 Infrared Spectrum of 1,3-Bis[ethoxymethyl(3,3,3-trifluoropropyl)silyl]benzene (Neat) ..... ............ .. 14

3 GPC Curve of 1,3-Bis [ethoxymethyl(3 ,3 ,3-trifluoropropyl)silyl]benzene ................ ..................... .. 15

4 GPC Curve of 1,3-Bis [ethoxymethyl (3,3,3-trifluoropropyl)silyl]benzene Containing an Impurity ...... .......... .. 16

5 Infrared Spectrum of Ethoxymethyl(3,3,3-trifluoropropyl)silylbenzene (Neat) ............ .................... .. 17

6 Infrared Spectrum of 1,3-Bis[hydroxymethyl(3,3,3-

trifluoropropyl)silyl]benzene (Neat) ..... ............ .. 18

7 GPC Curve of 1,3-Bis[hydroxymethyl(3,3,3-trifluoropropyl)silyl]benzene .................. ................... .. 19

8 GPC Curve of 1,3-Bis[hydroxymethyl(3,3,3-trifluoropropyl)silylj]benzene with Impurity ........ ............... .. 20

9 Infrared Spectrum of 1,3-Bis(dimethylamino)-l,3-dimethyl-1,3-bis-(3,3,3-trifluoropropyl)disiloxane (Neat) ......... 21

10 Infrared Spectrum of FASIL Polymer Sample No. 1 (Neat). . . . 22

11 Infrared Spectrum of FASIL Polymer Sample No. 2 (Neat). . . . 23

12 Infrared Spectrum of FASIL Polymer Sample No. 3 (Neat). . . . 24

13 GPC Curve of FASIL Polymer Sample No. 1 (q inh = 0.216) . . . 25

14 GPC Curve of FASIL Polymer Sample No. 2 (n inh = 0.258) . . . 26

15 GPC Curve of FASIL Polymer Sample No. 3 (n inh = 0.340) . . . 27

vi

SECTION I

INTRODUCTION

This report covers work carried out in support of the Air Force efforton the synthesis of novel high molecular weight fluoroalkylarylenesilox-anylene (FASIL) polymers (References 1, 2, 3, and 4) to be used in the sub-sequent development of aircraft integral fuel tank channel sealants to meetlong-life and broad-temperature range applications. Channel sealants for-mulated by AFML from this polymer exhibit improved fuel and oxidationresistance, coupled with better flexibility at low temperatures, when com-pared with all other candidate materials (Reference 5).

This work encompased the study of the synthesis of linear high molecu-lar weight FASIL polymers, their intermediates and monomers (Reference 4).

SECTION II

DISCUSSION

The synthesis of monomers, intermediates and high molecular weight FASIL

polymers is discussed in this section.

l. Synthesis of Monomers and Intermediates

The following sequence of reactions was followed to synthesize 1,3-bis[hydroxymethyl(3,3,3-trifluoropropyl)silyl]benzene, the diol.

CH3 YH3Cl-i-Cl + 2 C2 H5OH > C2 H5 0-Si-OC2H5 + 2 HCI

Rf Rf

YH3 CH3M T03

Br- -Br + 2 Mg + C2H50"Si'OC2H5 C2 H5 0-Si' ý'-•C 5 H5+ 2 MgBr 2

Rf if0 fCH• CH• CH• H

C. CH3 aq. NaOH C CM1 MC CH3

C2H50-Si-•[D -Si-OC 2 H5 aqf2NaO-P i-O-Si-ONa 2 'MO-Si-OH

f fRf 0 i f Kl2PO4 if2 ifRf = -CH 2 CH2CF 3

Treatment of methyl(3,3,3-trifluoropropyl)dichlorosilane with excess

ethanol gave methyl(3,3,3-trifluoropropyl)diethoxysilane. A Grignard reac-

tion of m-dibromobenzene with this compound gave the diethoxy Grignard inter-

mediate, l,3-[ethoxymethyl(3,3,3-trifluoropropyl)silyl]benzene, which must

be purified carefully to remove ethoxymethyl(3,3,3-trifluoropropyl)silyl-benzene, an impurity that probably results from partial reduction of m-di-

bromobenzene during the Grignard reaction. The monoethoxy material is

hydrolyzed to the silanol during the synthesis of the diol, and the silanol

acts as a chain stopper in the oligomer preparation.

Hydrolysis of the diethoxy Grignard product gave the diol, 1,3-bis[hy-

droxymethyl(3,3,3-trifluoropropyl)silyl]benzene. The diol could be purified

by flash distillation if all traces of base were removed, and using "pure"

diethoxy compound gave pure diol. The impurity in the diol which was identi-

fied as hydroxymethyl(3,3,3-trifluoropropyl)silylbenzene, was first detected

by gel permeation chromatography using Waters Micro Styrogel columns (106,

105, 10$, 103, 500, 102, 102 A) with tetrahydrofuran as solvent and a UV

2

detector. The corresponding monoethoxy derivative was found in the diethoxyGrignard compound before hydrolysis and its presence is shown in the GPC inFigure 4. The monoethoxy impurity appears at an elution volume of 73 ml,and,although it appears to be a major contaminant, it is actually present inless than 1% concentration (by GLC), but highly absorptive in ultra-violetlight. Its presence could be detected by TLC on silica gel with methylenechloride elutant as a small spot proceeding the diethoxy Grignard product.

Occasionally the diol would polymerize rather than distill during purifi-cation by flash distillation. This polymeric material could be reconstitutedto the diol by redissolving it in basic solution and neutralizing it againin the buffered solution.

The other monomer, 1,3-bis(dimethylamino)-l,3-dimethyl-l,3-bis(3,3,3-trifluoropropyl)disiloxane, was prepared by the following sequence of reac-tions.

ýH3 YH3 OH3Cl-Si-Cl + H20 - Cl-Si-O-Si-CI + 2 HC1

hf Rf if

CH03 OH3 H3 913Cl-Si-O-Si-Cl + 4 (CHB) 2NH -> (CH3 )2N-i-0- i-N(CH3 ) 2 + 2 (CH3 ) 2 NH2 CI

Rf Rf Rf Rf

Rf = -CH 2 CH2 CF3

The intermediate compound, 1,3-dichloro-l,3-dimethyl-l,3-bis(3,3,3-trifluoropropyl)disiloxane, was prepared by the addition of water to anexcess of methyl-(3,3,3-trifluoropropyl)dichlorosilane in ether. The bestyields were obtained when a 3:1 molar excess of dichlorosilane was employed.About 31% of the dichlorosilane could be recovered for reuse and the amountof higher boiling oligomers was kept to a minimum.

Treatment of the dichlorodisiloxane with excess dimethylamine gave thedimethylmnino monomer.

2. Initial Study of FASIL Polymer

The polymer was prepared by the reaction of the diol, 1,3-bis[hydroxymethyl-(3,3,3-trifluoropropyl)silyl] benzene, and the diamine, 1,3-bis(dimethylamino)-l,3-dimethyl-l,3-bis(3,3, 3 -trifluoropropyl)disiloxane.

3

?H3 9113 9113 013HO-Si-[3 -Si-OH + n (H3C) 2N-Si-O-Si-N(CH3 ) 2 --- >

Rf t f if if

H- -O 0 O-F•- i-O-i- -OH + 2n(CH3)2NHR f Rf ýf f

Rf = -CH2GH2CF3

The initial study of polymer preparation investigated the effect ofmonomer stoichiometry and, to a lesser extent, the effect of solvent. Meltpolymerizations, which gave higher molecular weight polymers, were conductedby heating about 5 g of the diol monomer with the desired amount of the dia-mine monomer at 1500 to 200' for 3 hr. Results were assessed in terms ofinherent viscosities, which were determined in tetrahydrofuran at 300 at aconcentration of 0.5 g per 100 ml. The polymers were hydrolyzed to removeany amino end groups and washed with methanol to remove any low molecularweight oligomers. The results are summarized in Table 1.

Polymerizations employing a solvent (toluene) gave lower molecularweight polymers, but decreasing the solvent amount gave higher molecularweights. Higher molecular weight polymers were obtained by melt polymeri-zations using a monomer stoichiometry (the ratio of diamine to diol) between95 and 100% with lower molecular weight polymers being formed on either sideof that range. Since the viscosity increased after a methanol wash for somepolymers, some lower molecular weight material was removed during that step.Experiment No. 16 shows the effect of adding the diamine in increments dur-ing the polymerization, and the viscosity appeared to peak near 947% ofstoichiometry.

3. FASIL Polymer Sample Preparation

At the request of AFML, three 50 g samples of FASIL polymers were pre-pared. The desired molecular weight ranges were 70,000, 90,000 and 110,000,and the corresponding inherent viscosities (from K = 1.89 x 10-4 and a =0.63 from the Mark-Houwink equation) were calculated to be 0.216, 0.253 and0.287 dl/g, respectively.

The preparation of these samples used a scale-up factor of 4 to 5 overthe initial polymer study. A small amount of toluene was used as solvent inthe first two samples to assist in dispersing the monomers (Table 2). Afterthe diol had dissolved, the solution was heated to reflux. Dimethyl amine

4

evolution began at about 550. The desired viscosity range was obtained byadding small increments of diamine. The melt polymerizations were conductedby first mixing the monomers and warming the mixture slowly to assist indissolving the diol. Usually the polymerization initiated at 50' with anaccompanying exotherm to 750 or higher and a rapid evolution of dimethylamine.

Experiment No. 7 (Table 2) was actually an attempt to prepare a polymerwith a viscosity near 0.287 dl/g, or slightly higher than Experiment No. 4.The last incremental addition of diamine raised the viscosity to 0.341 dl/g,and apparently during the hydrolysis to remove amino-end groups, additionalpolymerization occurred, because the viscosity was increased to 0.541 dl/g(Iyv = 300,000).

5

SECTION III

EXPERIMENTAL

Temperatures are recorded in degrees Centigrade. IR spectra weremeasured on a Perkin-Elmer Infracord 137 in the phases noted. NMR spectra

were measured on a Varian 360 A. GLC spectra, for quality control, weremeasured on a Perkin-Elmer Model 154 Fractometer. GPC curves were mea-sured on a Waters 301 UV detector (254 nm). Microanalytical work was per-formed by Sprang Microanalytical Laboratory. All inherent viscosities were

determined at 300 using tetrahydrofuran as solvent and at polymer concentra-tion of 0.5 g/100 ml.

1. Methyl(3,3,3-trifluoropropyl)diethoxysilane

In a 1-1, three-necked flask (flamed-dried under nitrogen) was placed422 g (2.0 moles) of methyl(3,3,3-trifluoropropyl)dichlorosilane. Absoluteethanol (230 g,5.0 moles) was added slowly in 1 hr. The reaction initiallywas endothermic and the temperature was maintained at 150 with an ice bath.The reaction mixture was purged with nitrogen while it was heated to 600 in2 hr. The excess ethanol was removed by distillation, and distillation ofthe residue (using an unpacked column) gave 382.8 g (82%) b.p. 920 (90 mm).(infrared spectrum, Figure 1).

2. 1,3-Bis[ethoxymethyl(3,3,3-trifluoropropyl)silyl]benzene

Into a 2-1 flask (flame-dried under nitrogen) was placed 40.0 g (1.65g-atom) of oven-dried magnesium turnings, 100 ml of THF, and 2-5 g of thetotal 188 g (0.80 mole) of 1,3-dibromobenzene, and the reaction was initiatedby use of a heating mantle. The remaining 1,3-dibromobenzene in 360 ml ofTHF was added in about I hr. After the mixture was refluxed for 4 hr, 450ml of THF was added, and the mixture was cooled to ice bath temperature.Methyl(3,3,3-trifluoropropyl)diethoxysilane (386 g, 1.6 moles) was added in

0.5 hr. The mixture was refluxed for 2 hr, then cooled to room temperatureand filtered. Solvent was removed from the filtrate on a rotary evaporator.The gummy residue was washed with about 3 liters of petroleum ether in a

Waring blender until the salts were a fine, white, free-flowing powder.

After the solvent was flashed off, distillation through a 4-plate Oldershaw

column gave 230 g (647%) of product, boiling range 100-108° (0.2 mm).

Redistillation through a 10-plate Oldershaw column gave pure material,b.p. 93-94P (0.05 mm), single pot, TLC. An infrared spectrum is shown in

Figure 2, and a GPC curve is shown in Figure 3. A GPC curve showing the

material before removal of "the impurity component" is shown in Figure 4.

6

When methyl(3,3,3-trifluoropropyl)diethoxysilane was added to theGrignard reagent at reflux instead of at 00, the yield of product was 47%(for eight reactions). Concomitant addition, where the diethoxysilane andm-dibromobenzene were added together, gave only a 34% yield. Inverse addi-

tion, where the Grignard reagent was added to the diethoxysilane,gave a 43%yield.

An impurity, ethoxymethyl(3,3,3-trifluoropropyl)silylbenzene, b.p. 800

(2 mm), n25 1.4451, is present in the early distillation fractions. Thismaterial can be hydrblyzed to the silanol, and if it is not removed at thisstep, it will carry over into the diol preparation and act as a chain stopperin polymerization reactions. An infrared spectrum is shown in Figure 5.

3. 1,3-Bis[hydroxymethyl(3,3,3-trifluoropropyl)silyl]benzene

This compound was prepared by a modification of the procedure describedby Pike (Reference 6). To a solution of 16.0 g (0.40 mole) of sodium hy-droxide in 15 ml of water and 70 ml of methanol was added 44.6 g (0.10 mole)of 1,3-bis[ethoxymethyl(3,3,3-trifluoropropyl)silyl]benzene in 5 min. Asolution of 16 g (0.40 mole) of sodium hydroxide in 80 ml of water was addedin 5 min, and the solution was stirred for 0.5 hr. After the solution waspoured slowly into a solution of 122.4 g (0.9 mole) of potassium phosphate(monobasic) in 1 liter of water and 500 ml of crushed ice, it was allowed tostand for 0.5 hr. The water layer was decanted from the lower viscous layerand extracted three times with 50 ml of methylene chloride. The lower viscouslayer was also extracted with two washes of methylene chloride. The combined

methylene chloride layers were washed four times with 100 ml of water, andstripped of solvent. A short-path distillation gave 37.2 g (94%) of diol,

b.p. 126-1320 (0.03 ram), (infrared spectrum, Figure 6). A GPC curve of thepure diol is shown in Figure 7 and a GPC curve of the diol with "the im-purity" is shown in Figure 8.

Sometimes during the course of a distillation of the diol, the materialin the distillation pot will undergo self-condensation to dimer and highermaterial because of the presence of trace amounts of base. Such material maybe reconverted to the diol as demonstrated by the following procedure:

The pot residue of an aborted distillation of the diol, weighing 80.9 g(0.207 mole based on the diolý was diluted with a solution of 49.8 g (1.245moles) of sodium hydroxide in 110 ml of methanol and 125 ml of water. Themixture was stirred for 5 hr and allowed to stand for 90 hr. The clearsolution was slowly poured into an ice water solution containing 170 g

(1.245 moles) of potassium phosphate (monobasic) and worked up as a regular

diol preparation. Distillation gave 68.6 g (85%) of diol boiling at 138-

1400 (0.08 mm).

7

4. l3-Dichloro-l,3-dimethyl-l,3-bis(3,3,3-trifluoropropyl)disiloxane

In a 500-ml flask (flame-dried under nitrogen) were placed 200 ml ofether and 211 g (1.0 mole) of methyl(3,3,3-trifluoropropyl)dichlorosilane.A solution of 6.0 g (0.33 mole) of water dissolved in 44 ml of tetrahydro-furan was added slowly with rapid stirring. Hydrochloric acid evolved dur-ing the addition was swept into a water trap with nitrogen. After the addi-tion was completed, the ether was removed by distillation. Distillation ofthe residue gave 64.6 g (31% recovery) of methyl(3,3,3-trifluoropropyl)di-chlorosilane, b.p. 75' (140 mm) and 80.3 g (66%) of the disiloxane, b.p. 110-1110 (15 mm).

The best yields were obtained when the molar ratio of dichlorosilaneto water was 3:1. Lower ratios of 2.25 and 2.5:1 gave yields of 55 and 58%,respectively, and a higher ratio of 4:1 gave about 53% yields.

5. 1,3-Bis(dimethylamino)-l,3-dimethyl-l,3-bis(3,3,3-trifluoropropyl)di-si loxane

About 70 ml of dimethylamine was condensed into a flask cooled to -70° andthen diluted with 475 ml of petroleum ether. As the temperature was main-tained at -200, 78.4 g (0.21 mole) of 1,3-dichloro-l,3-dimethyl-l,3-bis-(3,3,3-trifluoropropyl)disiloxane was added in 0.5 hr. The reaction mixturewas stirred at -200 for 0.5 hr and allowed to warm to room temperature. Thesalts were removed by filtration and washed with petroleum ether. The com-bined filtrates were stripped of solvent, and distillation of the residue gave61.3 g (75%) of product, b.p. 109-110' (9 mm) (infrared spectrum, Figure 9).

6. Initial Study of FASIL Polymer Preparation

The study of the preparation of high molecular weight FASIL polymersfrom the diol, 1,3-bis[hydroxymethyl(3,3,3-trifluoropropyl)silyl benzene,and the diamine, 1,3-bis(dimethylamino)-l,3-dimethyl-l,3-bis(3,3,3-tri-trifluoropropyl)disiloxane, dealt largely with the stoichiometry of themonomers, and to a smaller extent, with the effect of solvent amounts.Most of the experiments were carried out without a solvent (melt poly-merizations). The initial series of experiments is summarized in Table 1,and the general preparative procedure was as follows:

A flame-dried flask containing 5.003 g (0.0128 mole) of the diol and4.7038 g (0.0122 mole, 95% of stoichiometry) of diamine was heated to 1500in 1 hr and to 1950 in 2 more hours. The polymerization reaction generallyinitiated at 50' to 55'. A nitrogen sweep was maintained to remove thedimethylamine formed. The polymer was cooled to 1100, dissolved in 10 mlof toluene and I ml of water and refluxed for 0.5 hr to hydrolyze any

8

diamino end groups. The solvent and water were flashed off on a rotary

evaporator, and the residue was heated to 200' (0.1 mm) for 2 hr to removeall traces of solvent. The inherent viscosity of the polymer (determinedat 0.5 g/100 ml concentration in tetrahydrofuran at 300) was 0.184 dl/g.The polymer, washed with methanol and dried at 2000 (0.1 mm), weighed 8.1 g(97%) and had an inherent viscosity of 0.185 dl/g.

Experiment No. 16 is an example of incremental addition of the diamineto the polymer mix. Starting with 87% of stiochiometry, incremental amountsof diamine were added at 1-hr time intervals, and inherent viscosities weredetermined at each level. Such a procedure has been described by Patterson

(Reference 7) and allows the preparation of a polymer in a desired viscosityrange.

TABLE I

EFFECT OF SOLVENT AMOUNT AND MONOMER STOICHIOMETRYON FASIL POLYMER PREPARATION

Inherent InherentDiamine/Diol Solvent/Diol Viscosity Viscosity

Experiment Ratio Ratio Initial Finala/

No. (%) (ml/g) (dl/g) (dl/g)

1 90 Melt 0.139 0.1542 91 Melt 0.293 --

3 92.5 Melt 0.161 0.1644 95 Melt 0.142 0.1715 95 Melt 0.184 0.1856 95 Melt 0.248 --

7 97.5 Melt 0.144 0.1658 100 2:1 0.101 --

9 100 2.5:1 0.162 --

10 100 Melt 0.373 --11 101 Melt 0.995 0.16912 102 2:1 0.119 0.15713 102 1:1 0.160 0.16914 102 Melt 0.178 --15 105 2:1 0.095 --

16L/ a. 87 Melt 0.133 --

b. 90 0.136 --

c. 92 0.164 --

d. 94 0.188 --

e. 96 0 179 --f. 98 0.173 0.195

a! The polymer was washed with methanol.b/ The diamine was added incrementally.

9

7. FASIL Polymer Sample Preparation

Three 50-g polymer samples were prepared. The three molecular weight

levels desired and their corresponding inherent viscosities (calculated from

K = 1.89 x 10-4 and a = 0.63) were 70,000 (7 inh = 0.216), 90,000 (q inh =

0.253), and 110,000 (n inh = 0.287). These polymer samples were prepared

in about 25-g batches using the following procedure.

A solution of 19.9494 g (0.0512 mole) of diol (freshly distilled) and

19.7756 g (0.0515 mole) of the diamine monomer in 10 ml of toluene was re-

fluxed under nitrogen for 2 hr. The inherent viscosity (in tetrahydrofuran

at 30*) of the polymer at this stage was 0.142 dl/g. About 2 ml of water

and 10 ml of toluene were added and after I hr at reflux, the water was re-

moved in a Dean-Stark trap with toluene. To the solution was added 0.01 g

of diamine and after 2 hr at reflux the inherent viscosity of a polymer sample

was 0.213 dl/g. About 10 ml of toluene was removed by distillation, and after

4 hr at reflux, the inherent viscosity had increased to 0.258 dl/g. After

another hydrolysis, solvent was removed on a rotary evaporator and devoli-

talization at 200' (0.1 mm) for 2 hr gave 33.7 g (90%) of polymer with an

inherent viscosity of 0.263 dl/g.

The results of the three polymer preparations are summarized in Table

2. The two samples in each set were combined and the viscosity was re-

determined. These three samples were forwarded to the Air Force Materials

Laboratory. An infrared spectrum for samples 1, 2, and 3 are shown in

Figures 10, 11, and 12, respectively, and the GPC curves are shown in

Figures 13, 14, and 15.

The melt polymerization experiments (Nos. 5 and 6) were heated at 1750

for a total of 20 hr, during which time additional amounts of diamine were

added incrementally.

Experiment No. 7 gave a high molecular weight polymer (n inh = 0.541dl/g) that was beyond the desired range. A stoichiometric amount of monomers

in a small amount of toluene had been heated for 2 hr at 150'. Since the

viscosity (0.284 dl/g) at that time was near the desired level of 0.287 dl/g,

the polymer was hydrolyzed to remove any amino-end groups. After hydrolysis,

the viscosity had dropped to 0.085 dl/g; consequently, diamine monomer (0.4 g

total over a 4 hr period) was added incrementally until an inherent viscosity

of 0.341 dl/g was obtained. Hydrolysis treatment and devolatilization of the

polymer gave a material with an inherent viscosity of 0.541 dl/g, Mv =

300,000.

10

TABLE 2

SYNTHESIS OF HIGH MOLECULAR WEIGHT FASIL POLYMERS

Experiment Diamine/Diol Solvent/Diol inh Weight

No. M (ml/g) (dH/g) (g)

Sample No. 1 (7 inh desired = 0.216 dl/g)

1 100 1.5:1 0.210 27.52 100 1:1 0.220 25.6

1 + 2 -- -- 0.216 53.1

Sample No. 2 (n inh desired = 0.253 dl/g)

3 100 1:1 0.251 23.14 100 0.5:1 0.263 33.7

3 + 4 -- -- 0.258 56.8

Sample No. 3 (n inh desired - 0.287 dl/g)

5 100 Melt 0.285 37.66 98 Melt 0.328 29.5

5 + 6 -- -- 0.340 67.1

7 100 0.25:1 0.541 24.7

11

REFERENCES

1. Choe, E. W. and Rosenberg, H., "Arylenesiloxane Polymers for Use asHigh-Temperature Aircraft Integral Fuel Tank Sealants", AFML-TR-75-182, Part I, December 1976; ibid., Part II, December 1977.

2. Rosenberg, H. and Choe, E. W., Coatings and Plastics Preprints,37(1), 166 (1977); ibid., in Organometallic Polymers (C. E. Carraher,J. E. Scheats and C. U. Pittman, Jr. Eds.), Academic Press, New York1978.

3. Goldfarb, I. J., Choe, E. W. and Rosenberg, H., Coatings and PlasticsPreprints, 37(1), 172 (1977); ibid., in Organometallic Polymers(C. E. Carraher, J. E. Sheats and C. U. Pittman, Jr. Eds.), AcademicPress, New York, 1978.

4. Rosenberg, H. and Choe, E. W., Abstracts of Papers, 172nd Nat. Meet-ing, Amer. Chem. Soc., San Francisco, CA., August 1976, FLUO 41.

5. Rosenberg, H. and Choe, E. W., Coatings and Plastics Preprints,40(1), 793 (1979).

6. Pike, R. M., J. Polym. Sci., 50,151 (1961).

7. Patterson, W. J., S. P. McManus, and C. U. Pittman, Jr., Macromole-cular Syn., 6,99 (1977).

12

00

CN 0

- -r4

* 0 4

4-3

-4

T-.

ý4

0 00 ur C

13-

oo 0t C

-44

0

0 044

'41

Zo -

r-4

0 Wi

0

-4'-

-- 0

-- -0

0 0 0 C)

00 40

14-

41 --

Figure 3 -GPO Curve of 1,3-Bis[ethoxymethy1(3,3,3-trifluoro-propyl) silyl] benzene

15

i I t I

i f ! 1 ! 1 I f ; [ I ! i !

I t I I I I I I I I I i

=-ZýFf i l l i i : ! 1 " 1 1 1 1 1 f i l l i l l i

7b;:if

if,

==L7

I J;;To

;4+,LýU ýM' if I

I I t I I I I1 ! 1 1 J I

L 8044040 60 70

7777771 -H E.-L'9 , ' 1 1 '11 i H 1 , 1

Figure 4 GPC Curve of 1,3-Bis[ethoxyrnethyl(3$3,3-trifluoro-

propyl)silyl]benzene Containing an Impurity

16

oo 0 0

- 04

-i -r- 4-

I4-

.. .... . C )

CClq

LL-4

00

0n

(4-J4r

UU

4 -4

= **~. 0

0. : 0 X

17

0 o 0 N 0

zdJ ' ; .

-771

CV)

0 0

Zo- 00

cn

-00

184

Figure 7 -GPO Curve of I,3-Bis[hydroxymnethyI(3,3,3-trif1uoro-

propyl)silyl]benzene

19

44+, z±±

-4ý -ý4-+ 4++-ý 1.0it ;i

!EEE

4 -

1 t If

It

Ailit

41 L

-7-1

140.

1 1 ý 1 I f

'i f i f I

-60

if ;.-Itit

Figure 8 GPC Curve of 1,3-Bis[hydroxymethyl(3s3,3-trifluoro-

propyl)silyl]benzene with Impurity

20

0o C0 0O

NC

-4

C>~

00

oo UJ 0M -4

14-4

0

4. -4

(ci LOlIWN~

21q

CC

'0~_

0

zc:-4

00

-4

0 UCl

00

-u 0

4-42

C))

+ C)

0

i0 Co10 q C- t%) DNVLUIWSNVZI1

22

COc oI IC

IC _l i H "l11 i~ il f~l1 11 1 il i I ~ i d li l k i l i li l ll l l 11 1 1 i l 11 1 1 11 H lh ill ill lli ~ i l IN " Il ilh 111 Il l 1 111 111 111 1111 lil Ill 11 l ik ! hil

1 Il il 1 11 h il I 1, H I II 1 11 11 l ll I W HzIl i ill 1111 !111 1111 !i l N I IN ~ i lil

11111:1iliij~l j l'~ iIl~lC

mUiT i il i id H H T 1iil Il'!l I 111 11!1 !I il

I i ii i i~ i il [ ll j I 11 1L T I i I 1 1I H 11 1 i l il 1il 1 1 11 i l~ l ~ i i !I IM . l H 11 1 11 1 1 1 1 11 o11 tllI

11111 111J ll 1 0 0

111 11 J M ill ll ! 1i fl III II II I l l~ l il, H 4 1 11 il il 1 .11 !i l Il O

CN ~ ~ ~~ ~ ~ ~ ~ 1111 .I-Jlfll li:11!l1 ITit11 11hI l il11illilil~ ~ ~ ~ Ui i i r l il . i l l i iT I I I I l 1 1 1 l i l 11

!Il illh il :I11;1lli 11 i~ i lijil! ~ il .. ',T ! I I l H P 1 Hi l M

J !II HIM 1111W I 1, 111 1 Hll M 1111 . H il :1

H ilii~ i 0111111M HM M I ! kilhil IN 1, 'M !fil

11 , 1 1 1 i l i 1 111 , , I I l I II I II I M I I 1 ; 1 I l il il i li 1 11 1 :1 l i f I [ i lI i 1: 1 1i W ll i 1 1 , M M I 1 : W I 1 11 1 11 1 11 1 i C1 1I i M li,11T I W ~ itl i IT " lft +ýý If1111il i I CH l

o HI i(ill IIIL.4Nt'1-711It111 l

23 D

c01 v C

0

70

z

IMHIIII .t ~LII 11 o -4

444-4. o, 0

fillil Ilpi

II : 11 i f ilil if lI ;' I J JJ JJ [l l

00

1-4

0-0 [ifHH 11111 t!o "

Ill ~ ~ fif ilCIIINII IC

11.' Hil tl H l IIi

I l~ i 111 il 1 101ujlit 1111 it lit 111 1 lil -111 04L~0

011 02 it MIL A

> it 24

4- 7

4'I

46

L

I 4-t

II -

t i t

_ _ I

I A I -

Figure 13 -GPC Curve of FASIL Polymer Sample No. 1 ( inh 0.216)

25

t/ . . .t

: I ! l i l . . . .I f l l I

II . . .I I I

-lil

l• i l :: :Il l

; i t l i l . . . .

i l l $ i t I '

t i l l I ', I!

i 1 I I: I

-ii ! +I'~i I{• .•t

l i l t • •--. -

Figue 14- GC Cuve ff FSILPo~yer ampl No 2 ( [n = 0-58

I I I26

4 LTFII.LLL LI

I LLL .1 1 _LF I=- L

1 1 F I I I i I I I I 44_-ý 1 1 -+ ýý l -4 ,1

++- .:i7 #1 L

++_,L r7+4+ +H--',-

_0 L I Lit i t 1 ; 1 1 1

4ý -L -L. it-i I L

it

MT-L t-ELL-L.

_4

At

.- j i EL --- L I L it 1

_14Ei= El ITLL LL4ý

4I i I t+

1++ L

1 1; 14ý 1,11 ++4I-L I

1 ! 1 ; i f i l ; i I I t ' ll I I I [ ! i r P A i I2J .1 L

tt-t T-ý

44-

0 +++ 60 "ý-Týo20 30L4: LJ-I Tý I I

-7

Figure 15 GPC Curve of FASIL Polymer Sample No. 3 inh = 0.340)

27*U.S.Government Printing Office: 1979 - 657-002/535