Alkyl vinylidene cyanide polymers exhibiting nonlinear optical and piezoelectric properties

A second order nonlinear optically active medium comprises a thin film of a polymer which is characterized by repeating units corresponding to the formula:

• ##STR10## where R represents C.sub.1 -C.sub.6 primary alkyl group, P represents a vinyl monomer moiety, m and s are integers which total at least 50, and the m monomer comprises between about 10-50 mole % of the total (m+s) monomer units.

An electret film of a thermoplastic polymer which is characterized by repeating units corresponding to the formula ##STR11## where R represents a C.sub.1 -C.sub.6 primary alkyl group, P represents a vinyl monomer moiety, m and s are integers which total at least 50, and the m monomer comprises between about 10-50 mole % of the total (m+s) monomer units, and the film exhibits piezoelectric properties.

An electro-acoustic conversion or electro-mechanic conversion or pressure-sensitive device having an electret film component of a polymer which is characterized by repeating units corresponding to the formula:

• ##STR12## where R represents a C.sub.1 -C.sub.6 primary alkyl group, P represents a vinyl monomer moiety, m and s are integers which total at least 50, and the m monomer comprises between about 10-50 mole % of the total (m+s) monomer units, and wherein the film has an external field-induced net dipolar orientation of polymer molecules, and the film exhibits piezoelectric properties.