Take a look at the following product.
http://www.stabilant.com/

Stabilant 22 is an initially non-conductive amorphous-semiconductive block
polymer that when used in thin films within contacts acts under the effect of
the electrical field and switches to a conductive state. The electric field
gradient at which this occurs is established during its manufacture so that the
material will remain non-conductive
Thus, when applied to electromechanical contacts, Stabilant 22 provides the
connection reliability of a soldered joint without bonding the contacting
surfaces together!

Its switching speed is too slow to allow it to be used in the more traditional
semiconductor applications, however this means that signals of frequencies
substantiallyabove five cycles per hour will not be modulated by the switching
characteristics of Stabilant 22.
Chemically, Stabilant 22 is a polyoxyethylene-polyoxypropyline block polymer
with a molecular weight of about 2800. It has a very low vapor-pressure and
therefore there is no appreciable loss of material from evaporation. It has
been in some applications for more than fifteen years without renewal, and it
is probably safe to say that in the majority of cases, the equipment on which
it is used will be retired for obsolescence before the Stabilant must be
renewed.
In its undiluted form at room temperature Stabilant 22 has the viscosity of
medium weight motor oil, although it thins out with increasing temperature,
starting to decompose into the two polymers it is formed from about
240'Ceicius,