The third order nonlinear optical susceptibility, chi((3)), of an open-shel
l and alternant polymer based on a pi-conjugated polymer poly(1,2-phenylene
vinylene) bearing phenoxylradicals at 4-position, was evaluated. The real a
nd imaginary parts of chi((3)) of the poly(1,2-phenylenevinylene) derivativ
e were enhanced three orders of magnitude at ca. 680 nm and reached ca. 10(
-9) esu due to the phenoxyl radical formation.