Synthesis of polyfluorobutadiene by polymerization of perfluorobutadiene with diisopropyl peroxydicarbonat

Newman, J. M.

Toy, M. S.

English

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NOTICE 
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The invention is owned by NASA and is therefore available for 
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https://ntrs.nasa.gov/search.jsp?R=19700001947 2020-03-12T04:51:41+00:00Z
Inventors: Madeline S. Toy 
James M. Newrnan 
NASA Case NPO-10863 
Contractor: McDonnell-Douglas Astro- April, 1969 
nautics Co. 
Astropower Laboratory 
NEW POLYMERS OF PERFLUOROBUTADIENE 
AND METHOD OF MANUFACTURE 
Polyperfluorobutadiene can be used as a chemical 
resistant polymer and is further particularly useful as an 
intermediate to form higher molecular weight materials when 
it is cross-linked. Prior to the herein invention, conditions 
for polymerizing perfluorobutadiene were extremely severe and the 
yields quite poor. The object of this invention is to provide a 
simple method of such polymerization and greatly increase the 
yield of product. Further, in the course of development of the 
novel method of the invention, a new copolymer form of polyper- 
fluorobutadiene was found. 
The herein invention comprises polymerization of 
perfluorobutadiene utilizing diisopropyl peroxydicarbonate as 
a catalyst for the polymerization. The catalyst is miscible in 
the perfluorobutadiene monomer. Preferably at least one weight 
percent of catalyst is utilized. The catalyst and monomer are 
vacuum sealed in a reaction flask which is maintained at ambient 
temperature and the reaction is allowed to proceed at autogenous 
pressure. Reaction periods have been from 24 hours up to 
several weeks. The yield is a homopolymer, which is in fact a 
copolymer of perfluoro-1,2- and 1,4-butadiene. This is the first 
time that such a copolymer form has been identified. 
Prior to the herein invention, perfluorobutadiene required 
extremely high pressures, on the order of 10,000 atmospheres 
in order to achieve polymerization. This places severe limitations 
on the equipment utilized as well as greatly increasing the 
costs and hazards of producing the polymer. The herein method 
provides a much simpler method for achieving the polymerization. 
Further, as an additional benefit, it was found that the material 
was a copolymer of the 1,2- and 1,4-butadienes, thus providing 
double bonds on side chains that were along the main backbone 
of the polymer. These double bonds could be readily attacked 
for graft polymerization and other desirable cross-linking reactions. 
Contract No. NAS7-603 
Serial No. 848,325 
Filing Date August 7, 1969 
NASA NPO-10863 Serial No. 848,325 
Filing Date August 7, 1969 
S P E C I F I C A T I O N  
- - - - - - - - - - - - -  
TO ALL WHOM IT MAY CONCERN: 
BE IT KNOWN THAT, MAEELINE S. TOY and JAMES M. NEWMAN, 
citizens of the United States of America, residing at Fountain 
Valley, County of Orange, State of California, and Tustin, 
County of Orange, State of California, respectively, have 
invented new and useful 
NEW POLYMERS OF PERFLUOROBUTADIENE 
AND METHOD OF MANUFACTURE 
of which the following is a specification. 
' ABSTRACT OF THE DISCLOSURE 
ORIGIN OF THE INVENTION 
The invention described herein was made in 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, Public Law 83-568 (72 Stat. 435; 42 USC 2457). 
BACKGROUND OF THE INVENTION 
1. Field of the Invention: 
4 
This invention is in the field of new polymers and their 
method of manufacture. More particularly, the invention relates 
2. Description of the Prior Art: 
Prior to the herein invention, perfluorobutadiene had 
-1- 
the order of 10,000 atm. Though good yields were obtained, 
it can be readily appreciated that operating at such high 
pressures placed severe limitations on the equipment utilized, 
as well as greatly increasing the hazards and costs of 
producing the polymer. In some instances, catalysts were also 
utilized. However, the high pressures were still maintained. 
Additionally, the polyperfluorobutadiene that had been 
previously made and reported is indicated as being a relatively 
straight chain with the double bonds of the butadiene in 
the straight chain. Such double bonds are not often readily 
available for grafting monomer materials onto such a backbone 
and thus if one is desirous of such grafting or providing a cross- 
linked network, such a straight chain of polybutadiene is 
not particularly desirable. 
OBJECTS AND SUMMARY OF THE INVENTION 
An object of this invention is to provide a new method 
of forming polyperfluorobutadiene under mild reaction conditions. 
Another object of this invention is to provide a novel 
copolymer form of polyperfluorobutadiene. 
Still another object of this invention is to provide 
a method of obtaining polyperfluorobutadiene in high yield. 
The above and other objects of this invention are 
accomplished by initiating the polymerization of polyperfluoro- 
butadiene with diisopropyl peroxydicarbonate as a catalyst 
therefor. The peroxydicarbonate is dissolved directly in the 
liquid polyperfluorobutadiene and the reaction is preferably 
carried out in a sealed vessel at the autogenous pressure of 
the polymerization. The degree of the polymerization and the 
yield of the product depend upon the reaction temperature and 
1 1  the yield of polymer will increase with an increasing percent 
3 1 1  of catalyst. However, at the higher amount of catalyst the I 
4 1 1  polymer is of a lower molecular weight. Generally the reaction / 
5 temperature is preferably about ambient. Though the material 
6 1 1  can be heated, the resulting product will tend to have a I 
7 1 1  lower molecular weight. Analysis of the resulting 
8 1 1  fluorobutadiene indicates that it is a copolymer of perfluoro-1.2- 
9 1 and 1.4-butadiene , having the general formulas : I 
wherein x and y are positive integers. I 
1411 It can be seen that the foregoing copolymer has the advantage 
1 5 1  of a site change with terminal double bonds which are easily I 
sisceptible to cross linking reactions and graft copolymerizations. 
DESCRIPTION OF THE PREFERRED EMBODIMENTS 
It is believed that a free radical initiation mechanism I 
2o 1 1  is involved in the polymerization of perfluorobutadiene by 
21//  diisopropyl peroxydicarbonate. At relatively low temperatures I 
22 I1 diisopropyl peroxydicarbonate is a source of free radicals. 
231 The first step is a homolysis of the oxygen-oxygen bond into iso- 1 
24 1 propoxycarboxy radicals in accord with the following reaction: 1 
3011 
or a fraction of the radical of equation (1) may undergo 
31 1 1  decarboxylation: 
/ I  followed by chain initiations. I /  One particular advantage in the utilization of the 
4 / /  diisopropyl peroxydicarbonate catalyst is that it is miscible I 
5 
6 
9 1 1  weight percent is required, however, in order to obtain a I 
with the perfluorobutadiene monomer. It is believed that this 
miscibility particularly leads to the attainment of the high 
7 
8 
yield of polymer product. In carrying out the reaction, the 
amount of catalyst is not critical. Generally at least 0.10 
10 
11 
polymerization. As will be shown, there is a point of catalyst 
i 
percent where the molecular weight of the end polymer is 
12 
13 
maximized. Above this percentage of catalyst a decrease in 
polymer weight is obtained. The reaction is preferably carried 
14 
15 
18 1 1  chilled and evacuated vessel is then cooled in liquid nitrogen I 
out in a pressure bottle which has been chilled by ice bath 
or the like since the catalyst decomposes at 5OC. Thus, the 
16 
17 
1 9  / or dry-ice acetone bath and perf luorobutadiene is condensed . I 
solid catalyst is placed into the ice-bath chilled pressure 
vessel which is attached to a vacuum line and evacuated. The 
20 into the vessel. The bottle is then sealed or closed off from 
21 1 1  the vacuum line and the materials are continually mixed during 
2211 the course of reaction. The closed bottle can be heated to about 1 
2 3  50°C during the reaction period. which can last from 2 1  hours 
24 1 1  up to several weeks. Satisfactory results are obtainable, I 
25 / /  however, at ambient temperature and heating thus is not 
26 / (  necessarily required. However, at ambient conditions the I 
2711 yield is somewhat lower. At 50°C the liquid, mostly unreacted 
28 / /  monomer, remains colorless and solid polymer remains white. 
29 1 1  When heated above 50°C, such as 75OC, the liquid turns yellow 
and the solid polymer turns slightly yellow. The time of 
reaction required to obtain a product can be determined by 
a trial and error method for each set of conditions for the 
polymerization. One merely tests the resultant product at 
various lengths of time to determine that no further reaction 
has transpired. 
It is believed that the invention will be better 
understood from the following detailed examples: 
EXAMPLE I 
Into an ice chilled 125mm pressure bottle was placed 
3.4 grams of solid diisopropyl peroxydicarbonate. The pressure 
bottle was then attached to a vacuum line and evacuated while 
the bottle was cooling to a liquid nitrogen temperature. The 
bottle was then charged with 41.7 grams of perfluorobutadiene. 
Thus, the amount of catalyst was equivalent to 7.4 weight 
percent. The bottle was then sealed and heated with agitation 
under autogenous pressure at 50°C for two weeks. White polymer 
precipitated in the course of the reaction. At the end of 
the two week period, the pressure bottle was chilled to liquid 
nitrogen temperature to be opened, then attached to a vacuum 
line being evacuated, followed by warming to ambient to dis- 
charge the unreacted monomer under reduced pressure. At 
ambient temperature, the catalyst decomposes to gaseous products 
which are easily removed by evacuation. The white homopolymer 
resulting was then evacuated and dried at 50°C to give 25.2 
grams of white wax. This is equivalent to a 60% conversion to 
a polymer. The wax had a melting point between 73 and 76°C 
and a molecular weight of 1580. The infrared spectrum of the 
a s  evidenced by peaks a t  5.6 microns i n d i c a t i n g  t h e  per-  
f l u o r o v i n y l  group,  (-CF=CF2), and a t  5 .8  microns i n d i c a t i n g  
i n t e r n a l  -CF=CF- groups.  
EXAMPLE I1 
The procedure  i n  Example I was r epea t ed  excep t  t h a t  
t h e  amount of c a t a l y s t  was reduced t o  1 . 9  weight  p e r c e n t ,  
and t h e  po lymer iza t ion  temperature  was decreased  t o  ambient .  
Under t h e s e  c o n d i t i o n s  only  16% convers ion t o  a polymer product  
was ob ta ined .  The polymer, however, was a w h i t e  and ha rd  
e las tomer  having a me l t i ng  p o i n t  between 90' and lEO°C and 
molecular  weight  of a t  l e a s t  7070. The molecular  weight  of 
t h e  produc t  cou ld  have cons ide rab ly  exceeded t h e  7070 determined,  
however t h e  molecular  weight  was ob ta ined  by t h e  Ras t  method 
which l i m i t s  t h e  t e rmina t ion  t o  t h e  7070 f i g u r e .  The i n f r a r e d  
spectrum of t h e  homopolymer ob ta ined  once aga in  i n d i c a t e s  
copolymer per f luoro-1 ,2-  and l , 4 -bu tad i ene .  
EXAMPLE I11 
The procedure  of Example I1 was r epea t ed .  However, t h e  
amount of c a t a l y s t  was i nc reased  t o  2.7 weight  p e r c e n t .  A wh i t e  
hard  e l a s tomer  was ob ta ined  a f t e r  t h e  two weeks of r e a c t i o n .  
The y i e l d  was cons ide rab ly  improved, t o  31%. The produc t  had 
a me l t i ng  p o i n t  between 80' and 90°C and a molecular  weight  
of 5690. The i n f r a r e d  spectrum i n d i c a t e d  a copolymer per-  
f  luoro-1,2- and 1 ,4-butadiene.  
Thus it can be seen  from t h e  above Examples t h a t  t h e  
produc t  w i t h  t h e  h i g h e s t  molecular  weight  was ob ta ined  wi th  
t h e  s m a l l e s t  amount of c a t a l y s t .  However, a  p e n a l t y  was pa id  
i n  t h a t  t h e  y i e l d  was q u i t e  low. A l t e r n a t i v e l y ,  t h e  produc t  
w i th  t h e  h i g h e s t  y i e l d  u t i l i z e d  t h e  most c a t a l y s t ,  y e t  t h i s  
product as set forth in Example I was a light wax. The high 
yield of wax is particularly desirable because the low 
molecular weight wax is costable at low temperature. 
The polyperfluorobutadiene formed in accord with the 
method of the invention has good chemical resistance and can 
be used where a hard elastomer is desirable. Further, the 
polymer can serve as a prepolymer to form high molecular weight 
material that has excellent temperature and other properties. 


New polymers of perfluorobutadiene and method of manufacture Patent application

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