Preparation of electrically conductive polymers

A process for the preparation of electrically conductive polymers by polymerizing acenaphthylene, N-vinyl-heterocyclics, eg. N-vinylcarbazole or N-vinylpyridine, or N,N-divinylaniline at from -80.degree. to +100.degree. C. in the presence of a cationtic catalyst, wherein from 1 to 50 percent by weight of an oxidizing Lewis acid, preferably FeCl.sub.3, FeBr.sub.3, SbCl.sub.5, SbF.sub.5, AsF.sub.5 or CF.sub.3 -SO.sub.3 H, or a combination of AlCl.sub.3 or TiCl.sub.4 with the said compounds or with CrO.sub.3 or OsO.sub.4 is used as the catalyst. In a preferred embodiment of the process, thin films of the monomers to be polymerized, applied to glass or to a polymeric base, preferably to a plastic film, are treated with gaseous SbCl.sub.5, SbF.sub.5 or AsF.sub.5. The conductive polymers obtained can be used in the electrical industry for the production of solar cells, for the conversion and fixing of radiation and for the production of electrical and magnetic switches, as well as for the antistatic treatment of plastics.

The present invention relates to a process for the preparation of 
electrically conductive polymers by polymerizing acenaphthylene, 
N-vinyl-heterocyclics, eg. N-vinylcarbazole or N-vinylpyridine, or 
N,N-divinylaniline at from -80.degree. to +100.degree. C. in the presence 
of a cationic catalyst. 
These polymerization processes require from 0.001 to 10% by weight, based 
on weight of monomers, of the cationic catalysts in order to cause the 
polymerization to proceed. 
The polymerization of vinyl compounds with cationic catalysts has been 
disclosed (cf. W. R. Soerenson and T. W. Campbell "Preparative Methods of 
Polymer Chemistry", Interscience Publ., New York 1968, page 265). 
It has also been disclosed that electrically conductive polymers may be 
prepared by oxidative coupling of aromatic compounds by means of Lewis 
acids (cf. Naturwissenschaften, 56 (1969), 308). However, this process has 
only been carried out with aromatic and cycloaliphatic systems. The 
polymers obtained had relatively low molecular weights, with degrees of 
polymerization of up to about 50, and were accordingly brittle and 
difficult to process. 
It is an object of the present invention to provide high molecular weight, 
non-brittle polymers possessing good processability and high electrical 
conductivity. 
We have found that this object is achieved by using, as the catalyst for 
the polymerization of acenaphthylene, N-vinyl-heterocyclics, eg. 
N-vinylcarbazole or N-vinylpyridine, or N,N-divinylaniline, from 1 to 50, 
preferably from 10 to 40, % by weight, based on the weight of monomer 
employed, of an oxidizing Lewis acid. 
Preferred Lewis acids are FeCl.sub.3, FeBr.sub.3, SbCl.sub.5, SbF.sub.5, 
AsF.sub.5 and CF.sub.3 -SO.sub.3 -H, or a combination of AlCl.sub.3 or 
TiCl.sub.4 with the said compounds or with CrO.sub.3 or OsO.sub.4. 
In a particularly preferred embodiment, thin films of the monomers to be 
polymerized, applied to glass or to a plastic film, are treated with 
gaseous SbCl.sub.5, SbF.sub.5 or AsF.sub.5. 
The polymerization temperature used is from -80.degree. to +100.degree. C., 
preferably from -30.degree. to +100.degree. C. The polymerization process 
according to the invention can be carried out in conventional solvents and 
auxiliary fluids but can also be carried out as a mass polymerization. 
A particularly preferred embodiment is an oxidative cationic polymerization 
wherein thin films of the above monomers, applied to one or both sides of 
glass or of a polymeric base, preferably a polymer film, are polymerized 
by means of gaseous initiators, eg. SbCl.sub.5, SbF.sub.5 or AsF.sub.5. 
The polymers prepared by the process according to the invention are soluble 
and have intrinsic viscosities of [.eta.]&gt;0.5, ie. molecular weights 
greater than 25,000 (according to the conversion formula given in 
Macromolecular Synthesis, volume I (1974), 83, published by John Wiley, 
New York). The polymers thus produced have electrical conductivities of 
about 10.sup.-10 --10.sup.-3 S/cm, depending on the amount of catalyst 
which has remained in the polymer. 
By increasing the amount of catalyst employed according to the invention, 
during or after the polymerization, to figures of up to 50% by weight, it 
is possible to achieve electrical conductivities of up to 10.sup.+2 S/cm. 
The electrical conductivity is measured by the method of F. Beck, Ber. der 
Bunsenges. 68 (1964), 559. 
The electrically conductive polymers prepared according to the invention 
and having conductivities greater than 10.sup.-2 S/cm may be used for the 
antistatic treatment of plastics, for the production of solar cells, for 
the conversion and fixing of radiation and for the production of 
electrical and magnetic switches. The addition of the strong Lewis acids 
to the monomers or polymers results in p-conductors (cf. J. Chem. Educ., 
46 (1969), No. 2, 82.