I
GlFFlN D. JONES, JAMES R. RUNYON, and JOSEPHINE ONG' Physical Research Laboratory, The Dow Chemical Co., Midland, Mich.
Isobutylene Copolymers Styrene derivatives can be copolymerized into useful polymers with reactive halogens
STYRENE DERIVATIVES, vinylbenzyl chloride and isopropenylbenzyl chloride, were prepared and copolymerized with isobutylene and propylene to produce polymers with reactive halogens. These copolymers were vulcanized, either with amines or with a conventional butyl rubber cure. Permselective membranes were prepared from copolymers rich in benzyl chlorine.
T H E
Preparation of Monomers Vinylbenzyl chloride was prepared by the dehydrochlorination of a-(chloroethy1)benzyl chloride (4, and was a mixture of ortho and para isomers, 30 to 40% ortho. og-Isopropylbenzyl chloride (8970 para, 11% ortho) was chlorinated a t 50' C. under ultraviolet light. The product dehydrochlorinated during distillation, but with two distillations, a fraction boiling at 73' to 74' C. at 0.03 mm. contained 84.870isopropenylbenzyl chloride by unsaturation determination. By a single crystallization, monomer of 96.7%, purity was obtained. The purified monomer was all para, had a boiling point of 96' C. at 5 mm., freezing point 27.34' C., ND30 1.5600, and d30 1.0573. Vinylbenzyldimethylamine was prepared by adding vinylbenzyl chloride to a dioxane solution of aqueous dimethylamine a t room Jemperature. A purified fraction, 90% para, 10% ortho, had a boiling point of 82O to 83' C. at 5 mm. The boiling point reported for the ortho isomer is 102O C . at 17 mm. (7).
and ethyl chloride. All equipment was swept for several hours with dry, oxygen-free nitrogen before use, and a slow stream of nitrogen was passed into the reactor during polymerizations to prevent entrance of moisture. The styrene derivative was washed with caustic to remove inhibitor, and dried over calcium chloride. The isobutylene and ;he ethyl chloride, used as diluent for the reaction, were dried in the gas phase before being condensed into the reaction flask. Boron trifluoride was added either above or below the liquid surface a few milliliters a t a time. After a n induction period of variable length (due to varying amounts of residual moisture), the effect of each addition of boron trifluoride could be noted as a temperature rise. The polymer was purified by repeated precipitations from toluene. The composition of the resulting copolymers, as indicated by chloride determinations, was considerably different from that of the starting monomer mixture. Vinylbenzyl chloride proved to be considerably less reactive than isobutylene, while isopropenylbenzyl chloride was somewhat more active. The r l , r2 values, calculated by the method of Mayo and Walling ( 3 ) , are given in the table.
Values for Styrene Derivatives (MI) and Isobutylene (Mz) Mi 71 r2 Vinylbenzyl 0 . 7 2~0.1 4 . 5 1 chloride Isopropenyl benzyl 1 0.4 chloride Styrenea 0.6 i 0.3 3 1* r1, r2
*
a References (1, d , 6). Reference ( 8 ) .
References (1, 6).
Reactive Site Available The benzyl chlorine provides a site further reaction with a variety of nucleophilic reagents. Thus these copolymers can be aminated or otherwise substituted to impart special properties. Cross linking can be accomplished by various means. The ease of cross linking and the properties imparted depend on the amount of benzyl chlorine in the copolymer, its molecular weight, and the crosslinking agent chosen. Copolymers con0 chlorine taining as little as 0.8 mole 7 were cross-linked to insoluble polymers. Ammonia, methyl, ethyl, and propyl amines cross linked chlorine-containing polymers even when present in excess. Higher mono amines failed to do so at ~~~~
Copolymers of Isobutylene Pofenfial uses
Copolymerizations
b
Cationic rubber like butyl rubber
The polymerizations were carried out a t about -looo C. in a 1-liter stirred glass reactor cooled with liquid nitrogen
b
Sites for grafting polymerization
Present address, Department of Chemistry, Oregon State College, Corvallis,
* .
1 6c
0.17
Permselective membranes
Ore. VOL. 53, NO. 4
APRIL 1961
297
a detectable rate, probably because of the decrease in nucleophilicity caused by the increasing steric hindrance of the product first formed. Treatment of a low viscosity copolymer (IOOj, solution in toluene had a viscosity of 29 cps.) containing 5.17 mole % vinylbenzyl chloride with a polyamine, 3,3 '-diaminodipropylamine, at 110' C. for 4.5 hours increased the tensile strength from about 20 to 237 p.s.i. A sample of about twice the viscosity, but about the same chlorine content. increased in tensile from 220 to 500 p.s.i. under similar treatment. With a higher initial viscosity, curing produced more interesting rubbers. A sample having a lOy0 viscosity of 148 cps. and only 1.3 mole Yo isopropenylbenzyl chloride gave a rubber with a tensile of 730 and elongation of 200 with the above treatment. With a "standard" rubber cure (sulfur, stearic acid, tetramethylthiuram disulfide, 2mercaptobenzothiazole, zinc oxide, and carbon black), this same copolymer gave rubber with a tensile strength of 1780 p.s.i. and 760% elongation, which compares favorably with butyl rubber. Morrissey (5) has described bromineand chlorine-containing butyl rubber which can be vulcanized Tvith various conventional rubber cures. Our copolymers should have more stability in the unvulcanized state than Morrissey's halogenated aliphatics.
Permselective Membranes Permselective membranes were prepared by casting films of copolymers containing 50 to 60 mole 70 vinylbenzyl chloride. These films were simultaneously quaternized and cross-linked by immersion in a mixture of dimethylethanolamine and diethylenetriamine for 2 days. The properties of these films are shown above along with two commercially available membranesRohm and Haas Amberplex C-I and in Ionics CR-51. A high specific conductivity is desirable, and permselectivity of 1.0 is perfect. Our conductivity is somewhat higher than the examples, but selectivity is lower.
298
Permselective Membranes Specific
Triamine, S T t . yo
Conductivity, Mhos/Cm.
Perniselectivity
51.5
10 20
14 x 1 0 - 3 1 1 . 3 x 10-3
61
20
0.685 0.905 0.75 0.98 0.97
Copolymer Mole % VBC
Amberplex C-1 Ionics CR-51 Ci - --_0.05 _:\I_
cy
19 x 10-3 I x 10-3 7 x 10-3
0.1 N
Vinyl-Bearing Polymers for Grafting An attempt was made to produce a site for grafting by aminating the benzyl chlorine with a vinyl-bearing amine:
ployee at Dow in 1954, and of W. K. Glesner on this project. The mechanical tests were made by Leo Kin or this laboratory.
copolymer
-I
H I
>\
I
n
CH 3
i +
CH%-N-CH
2-
I L",
c1
Amination of the copolymer was attempted in cumene solution and bromine consumption of the Product indicated that the reaction had proceeded at least to half the theoreiical conversion. The vinyl-containing polymer was recovered by precipitation, dissolved in a-methylstyrene, and a grafting copolymerization was attempted, using sodium biphenyl complex for catalyst. The polymers formed showed no improvement in properties over poly-nmethylstyrene. They showed, in fact, the presence of incompatible polymers, suggesting that grafting was incomplete.
Acknowledgment The authors wish to acknowledge the work of D. F. Barringer, a summer em-
INDUSTRIALAND ENGINEERINGCHEMISTRY
Literature Cited (1) Leary, R. F. (to Standard Oil Development C o . ) , U. S. Patent 2,641,595
/June 9.1953).
(2)' Ludwig, E: B., Gantmacher. A. R., Medvcdev, S. S., Sect. 3, paper 12, Sym-
posium on Macromolecules, Internatl. Union Purc and Appl. Chcm., Wicsbaden, Germany, November 1959. (3) Mayo, F. B.. Walling, C., Chem. Reis. 46, No. 2. 191 (1950). (4) McMaster, E. L., Stowe, S. C. (The Dow Chemical Co.), Brit. Patents 792,859. and 792,860 (April 2, 1958). (5) Morrissey. R. T., IND. ENG. CHEDI. 47, 1562-9 (1955) ; Rubber World 138, 725 (1958). (6) Tegge, D. R. (to Standard Oil Development Co.), U. s. Patent 2,643,993 (June 30. 1953). (7) Von Braun, J., Ber. deut. chem. Ges. 50, 45 (1917). RECEIVEDfor review August 24, 1960 ACCEPr m January 30, 1961
