K. Usami et al., Anisotropic decomposition of polyimide molecules induced by irradiation oflinearly polarized UV light, MOLEC CRYST, 347, 2000, pp. 269-279
We have investigated the anisotropic decomposition of polyimide (poly[bis(4
,4'-oxydiphenylene)-dimetylmetyl-pyromellitimide]) molecules induced by exp
osure to linearly polarized ultraviolet light (LPUVL) of wavelength similar
to 300 nm. The decomposition of the polyimide molecule was monitored by me
asuring the polarized infrared (IR) absorption spectra as a function of LPU
VL exposure. We propose an empirical equation that describes the relation b
etween the orientational distribution of polyimide chains and LPUVL exposur
e. We consider two decomposition rates beta (//) and beta (perpendicular to
) for the polyimide chains oriented parallel and perpendicular to the polar
ization direction of LPUVL, respectively. By taking account of the increase
the decomposition rates around 30 J(.)cm(-2), the IR absorption data could
be reproduced with beta (//)/beta (perpendicular to) = 1.23 +/- 0.02. The
decomposition rate beta (//) is (4.5 +/- 1.0) x 10(-3)J(-1.)cm(2) for the L
PUVL exposure range up to similar to 30 J cm, and (1.6 +/- 0.1) x 10(-2) J(
-1.)cm(2) beyond similar to 30 J.cm(-2).