Compositions of poly(fluoroacetylene) useful for providing electrically conductive properties to plastics by a method of dehydrofluorination of saturated fluoroethylene polymers.

BACKGROUND OF THE INVENTION 
Preparation of plastic materials of high stability with electrically 
conductive properties has been a major goal of the plastic and electronics 
industry for some time. Such a plastic product would, for example, 
revolutionize the battery powered electric motor industry, such as in the 
automotive field, by making light weight batteries of high storage 
capacity available. In such batteries the lead plates would be replaced 
with a relatively light weight plastic material, making long range 
electric powered automobiles a reality. 
Such light weight plastics with electrical conductive properties would also 
be beneficial in solar to electrical conversion equipment and provide 
equipment of far lighter weight. Such plastics would find a myriad of uses 
in many varying types of electrical equipment or in components thereof. 
The production of isolatable films of poly(fluoroacetylene) or 
poly(difluoroacetylene) by the basic dehydrofluorination of 
poly(vinylidene fluoride) or poly(trifluoroethylene) containing polymers 
has not been reported in the literature. 
A number of experimentors have proposed such dehydrofluorination but have 
failed to achieve such dehydrofluorinated polymers. For examples, in a 
brief report by McCarthy and Dias [Chem. & Eng. News. Sept. 5, 1983, p. 26 
and Preprints of the Division of Polymeric Materials Science and 
Engineering, 49, 574 (1983)] the authors speculated that poly(vinylidene 
fluoride) would undergo dehydrofluorination when treated with aqueous 
caustic using a phase transfer catalyst. The authors isolated a polymer 
containing ketone groups after treatment with aqueous sulfuric acid. 
In U.S. Pat. No. 2,857,366 that issued Oct. 21, 1956 to Middleton, 
monofluoroacetylene was prepared by thermal decomposition of 
monofluoromaleic anhydride and monofluoroacetylene polymers prepared 
therefrom. Such a process is expensive, dangerous, and is limited to 
monofluoroacetylene. 
In Japanese Patent Jpn Kohai Tokkyo Koho JP No. 58 59,208 [83 59,208] April 
3, 1983 by Mitsubishi Chemical Industries Co., Ltd. (Chem. Abstr. 99, 
140600q 1983) poly(difluoroacetylene) was prepared by the polymerization 
of difluoroacetylene monomer in tetrahydrofuran solution at 0.degree. C. 
The process of the present invention merely removes HF from a wide variety 
of existing, commercially available, fluorine substituted polymers in a 
relatively inexpensive treatment with a basic solution. No catalyst is 
required for the process to proceed at commercial rates, although such 
catalysts might be economically beneficial for some conversions. 
BRIEF SUMMARY OF THE INVENTION 
The process of the invention is defined as a process for 
dehydrofluorinating a fluorine substituted polymer to provide a 
dehydrofluorinated polymeric composition which comprises treating a 
starting polymer selected from the group of starting polymers consisting 
essentially of a homopolymer of vinylidene fluoride monomeric units or 
trifluoroethylene monomeric units, copolymers or terpolymers containing a 
major portion of vinylidene fluoride monomeric units with at least one 
copolymerized monomeric unit selected from the group consisting 
essentially of hexafluoroproplene, trifluoroethylene, vinyl fluoride, 
vinyl chloride, chlorotrifluoroethylene, and mixtures of the homopolymer, 
copolymer, and terpolymer; with a basic solution for a sufficent period of 
time to remove HF from the polymer to provide a dehydrofluorinated polymer 
having at least 5 monomeric mol percent of the dehydrofluorinated unit 
##STR1## 
wherein X is H or F and the dehydrofluorinated units form conjugated 
double bonds that impart electrical conductivity to articles prepared from 
the dehydrofluorinated polymer. 
The starting polymers can be in film or powder form and the basic solution 
can contain alkali hydroxides or organic amines. 
It is preferred that the basic treatment solution include at least one 
solvent selected from the group consisting essentially of water, dimethyl 
formamide, dimethyl acetamide, dimethyl sulfoxide, methanol, ethanol, and 
butanol. 
It is preferred that the basic solution contain either sodium hydroxide, 
potassium hydroxide, lithium hydroxide, rubidium hydroxide, 
tetrabutylammonium hydroxide, or a tetrabutylammonium halide to provide a 
treatment pH within the range of about 10 to about 14. 
Preferably, the starting polymer is treated to provide at least 40 
monomeric mol percent of the dehydrofluorinated units. 
Monomeric mol percent, with respect to the repeating dehydrofluorinated 
unit in (b), is the number of monomer units in the polymeric composition 
having a conjugated double bond divided by the total number of monomer 
units forming the particular polymer, times 100. 
It is, of course, understood that other noninterfering monomeric units can 
be included or other polymers, such as polyacrylates, grafted onto the 
polymeric composition of the invention while remaining within the spirit 
and scope of applicant's invention. 
Typically, the starting polymer is treated with the basic solution for a 
time period of at least about five minutes at a temperature within the 
range of about 20.degree. C. to about 100.degree. C. 
The product or composition of this invention is defined as a fluorine 
substituted, conjugated carbon-to-carbon double bond containing polymeric 
composition that imparts electrical conductivity to structures made 
therefrom, consisting essentially of 
(a) 0 to 95 monomeric mol percent of (i) vinylidene fluoride monomeric 
units or trifluoroethylene monomeric units, or (ii) a major portion of 
vinylidene fluoride monomeric units with at least one copolymerized 
monomeric unit selected from the group consisting essentially of 
hexafluoropropylene, trifluoroethylene, vinyl chloride, vinyl fluoride, 
chlorotrifluoroethylene, and tetrafluoroethylene monomeric units, and 
mixtures of (i) and (ii); and 
(b) 100 to 5 monomeric mol percent of the unit 
##STR2## 
wherein X is H or F and the monomeric units of (b) are arranged to form 
conjugated double bonds, with the proviso that when a homopolymer of 
(a)(i) is present, the mol percent in (b) is 95 to 5 and the mol percent 
in (a) is 5 to 95, to provide a polymeric composition that imparts 
electrical conductivity to articles prepared therefrom. 
The preferred monomeric units in (a)(i) above are vinylidene fluoride or 
trifluoroethylene or both vinylidene fluoride and trifluoroethylene. It is 
preferred that the monomeric mol percent of the dehydrofluorinated unit in 
(a)(ii) above be at least 40. The product of the invention includes 
electrically conductive film and tubular structures, or other shapes, 
formed of the above polymeric compositions. 
DETAILED DESCRIPTION OF THE INVENTION 
The product of the invention is prepared by treating the appropriate 
commercially available, fluorine substituted polymer, in film or powder 
form, with a basic treatment solution (preferred pH of 10 to 14) that 
removes HF to such an extent that at least 5 monomeric mole percent of the 
treated polymer contains double bonds. The double bonds are conjugated, 
which means that at least 5 mole percent of the double bond containing 
units occur in pairs to provide a sequence of: single, double, single, 
double, single bonds. Other dehydrofluorinated units may occur, 
permissively, randomly throughout the polymer chain, but these units are 
not included in the threshold of 5%. 
By way of illustration, equations I, II, and III below illustrate the 
process where full dehydrofluorination occurs. In I the starting polymer 
is poly(vinylidene fluoride) to provide poly(monofluoroacetylene) (PMFA); 
in II the starting polymer is poly(trifluoroethylene) to provide 
poly(difluoroacetylene) (PDFA); and in III the starting polymer is a 
copolymer of vinylidene fluoride and trifluoroethylene to provide 
poly(monofluoroacetylene, difluoroacetylene) copolymers. 
##STR3## 
It is thus apparent, that the X substituents forming the adjacent pairs of 
dehydrofluorinated units 
##STR4## 
that form the conjugated double bonds, need not be the same. X can be H in 
one unit and F in the adjacent unit, or X could be the same in adjacent 
units. Moreover, the degree of dehydrofluorination can be such that from 5 
to 100 monomeric mol percent of the polymer contains the 
dehydrofluorinated units that occur in pairs. 
The polymeric composition of this invention may be prepared by the basic 
dehydrofluorination of poly(vinylidene fluoride) and 
poly(trifluoroethylene) and copolymers incorporating either or both of 
these polymers. The bases are derived either from alkali hydroxides or 
organic amines in aqueous or organic solvents at room temperatures 
(preferably 25.degree. to 100.degree. C. at pH of 10 to 14). The period of 
treatment is from about five minutes to 90 hours, or longer. 
Preferred solvents for the basic solution are those selected from water, 
dimethyl formamide, dimethyl acetamide, dimethyl sulfoxide, methanol, 
ethanol or butanol. 
Typical bases that can be included in the basic solution are: sodium 
hydroxide, potassium hydroxide, lithium hydroxide, rubidium hydroxide, and 
either quaternary ammonium compounds such as tetrabutylammonium hydroxide 
or tetrabutylammonium halides. 
In some cases the addition of a surfactant aids the rate of reaction. 
Optionally aliphatic, heterocyclic or aromatic amines such as 
triethylamine, pyridine, quinoline and salts derived from them, can be 
used as the basic producing agent.

The following examples illustrate the invention and are not to be taken as 
a limitation thereof. 
EXAMPLE 1 
To a mixture of 45 ml of 10% alcoholic potassium hydroxide (prepared from 
10 g KOH and 90 g of ethanol) and 10 ml of dimethyl acetamide (DMAC) as 
solvent at 25.degree. C. was added 0.005 g of a piece of commercially 
available poly(vinylidene fluoride) film (Kynar.RTM. 900 film, of about 
0.003 in. thickness having about 2,400 monomer units, sold by Pennwalt 
Corporation under the Kynar trademark). After 90 hours at 25.degree. C. 
the film turned brown and the solution was orange in color. The film was 
washed with water, dried and an infrared (IR) spectrum run on both the 
treated and untreated film. A comparison of the IR spectra show that 
significant amounts of poly(fluoroacetylene) was produced, as evidenced by 
the absorption bond at the 1595.7 wave number which is absent in the 
spectrum of the untreated poly(vinylidene fluoride) film. 
EXAMPLE 2 
12.8 of a commercially available powdered poly(vinylidene fluoride) 
homopolymer (Kynar.RTM. 901, sold by Pennwalt Corporation) was dissolved 
in 150 ml of DMAC and added to a solution of 11.2 KOH in 100 ml CH.sub.3 
OH, to provide a gel. The gel was washed with water and dried at 
100.degree. C. overnight to provide 9.5 g of product. The product was not 
soluble in DMAC, methyl isobutyl ketone (MIBK), or NaOH solution, and had 
a melting point in excess of 300.degree. C. The IR spectra for the product 
showed an absorption band at about 1600 wave number [corresponding to 
poly(difluoroacetylene) units] which was absent with the starting polymer. 
The C, H, and F analysis in weight percent was: 
______________________________________ 
C H F 
______________________________________ 
Starting Polymer 
38.8 3.00 59.10 
Final Product 
48.6 3.16 38.60 
______________________________________ 
which also shows significant elimination of HF to provide the conjugated 
double bonds in the product (monomeric mole percent about 100 would be 
equal to a polymer with 43% fluorine). 
EXAMPLE 3 
3.0 g of a commercially available poly(vinylidene fluoride) powder (sold 
under Kynar.RTM. trademark of Pennwalt Corporation) was dissolved in 100 
ml DMAC and then the solution added to 21 g of 
1,8-diazabicyclo[5,4,0]undec-7-ene. After 3 to 4 minutes the solution 
turned black. The next day the black solid was filtered, washed and dried 
at 110.degree. C. to provide 2.6 g of product. The product did not show 
any melt flow behavior and exhibited an IR absorption at a wave number of 
about 1600, indicating the presence of poly(difluoroacetylene) units. The 
C, H, and F analysis in weight percent was: 
______________________________________ 
C H F 
______________________________________ 
Starting Polymer 
38.8 3.00 59.10 
Final Product 
39.8 3.44 54.20 
______________________________________ 
which indicates elimination of a substantial amount of HF to form the 
conjugated double bonds (approximately 30 mole % dehydrofluorination). 
EXAMPLE 4 
To a flask containing a solution of 4 g (0.1 mole) of sodium hydroxide in 
20 ml of water and the mixture stirred magnetically at 70.degree. C. for a 
few minutes. Then 1.0 g of poly(trifluoroethylene) film was added 
(softening point of 200.degree.-202.degree. C.). The flask was sealed with 
a stopper and the mixture stirred at 70.degree. C. for five hours. The 
polymer turned dark brown and the solution was amber colored. The polymer 
film was rinsed with water and dried at room temperature for three days. 
In infrared spectrum of the film (attenuated total reflectance) shows that 
poly(difluoroacetylene) was produced as evidenced by absorption at the 
1618.9 wave number which is absent in the control (before reaction) film. 
EXAMPLE 5 
This example illustrates severe over dehydrofluorination of the 
commercially available polyvinylidene fluoride powder of Example 2. 
1.5 g of the Kynar.RTM. powder in 50 ml of DMAC was added to 10.7 g of 96% 
1,8 diazabicyclo [5,4,0]undec-7-ene, then heated at reflux for 3 hours and 
allowed to remain at room temperature. The resulting polymer product 
obtained by filtration was then washed with water and dried. 
The final product analysis of C, H, and F (weight %) was: 
______________________________________ 
C H F 
______________________________________ 
Starting Polymer 
38.8 3.00 59.10 
Final Product 
67.6 5.52 7.68 
______________________________________ 
which indicates severe over dehydrofluorination as the final F% is 7.68, 
whereas at 100 mol percent of the conjugated double bond containing 
monomeric unit, the %F should be about 43%. 
EXAMPLE 6 
To a stainless steel pressure vessel was added 1.0 g of poly(vinylidene 
fluoride) powder and 10 ml of triethylamine. The temperature was raised to 
110.degree.-155.degree. C. (20-60 psig) and held there for 7 hours. The 
vessel was cooled, opened and the solid polymer washed with water. After 
drying at 110.degree. C. the polymer had an analysis of C, H, and F as 
follows: 
______________________________________ 
C H F 
______________________________________ 
Starting Polymer 
38.8 3.00 59.10 
Final Product 
41.7 3.08 53.00 
______________________________________ 
This corresponds to about 37.5% dehydrofluorination. 
EXAMPLE 7 
To a flask containing the caustic solution described in Example 4 is added 
1.0 g of poly(vinylidene fluoride/trifluoroethylene) copolymer (22.8% 
trifluoroethylene content) and reacted as in Example 4. The infrared 
spectrum of the dried film indicates that dehydrofluorination took place 
to a polyacetylene structure as indicated in the absorption at about 1609 
wave number. 
EXAMPLE 8 
Other starting polymers, including copolymers and terpolymers containing a 
major portion of vinylidene fluoride monomeric units with at least one 
copolymerized monomeric unit selected from the group consisting 
essentially of hexafluoroproplene, trifluoroethylene, vinyl fluoride, 
vinyl chloride, chlorotrifluoroethylene, and mixtures of the copolymers, 
terpolymers, or homopolymers of vinylidene fluoride or trifluoroethylene, 
can be dehydrofluorinated by treating similarly as described in the 
preceding Examples 1-4 and 6-7, to provide the polymeric composition of 
the invention. The severity of the basic treatment, including the strength 
of the basic solution, time and temperature of exposure can be regulated 
to provide the degree of HF elimination desired to yield a polymer with up 
to 100 mole percent of conjugated double bond containing units.