INFLUENCE OF POLING METHODS ON THE ORIENTATIONAL DYNAMICS OF 2-METHYL-4-NITRO-ANILINE IN POLY(METHYL METHACRYLATE) STUDIED BY SECOND-HARMONIC GENERATION
Pc. Ray et Pk. Das, INFLUENCE OF POLING METHODS ON THE ORIENTATIONAL DYNAMICS OF 2-METHYL-4-NITRO-ANILINE IN POLY(METHYL METHACRYLATE) STUDIED BY SECOND-HARMONIC GENERATION, European Polymer Journal, 32(1), 1996, pp. 51-55
The magnitude and stability of the induced dipolar orientation of 2-me
thyl-4-nitroaniline (MNA)/poly(methyl methacrylate) (PMMA) guest/host
system is investigated. The chromophores are aligned using both the co
rona discharge and contact electrode poling techniques. The magnitude
of order parameter (also an indicator for the second order nonlinear s
usceptibility) is measured by recording absorbances of the poled (by t
he two different techniques) and unpoled PMMA films at different conce
ntrations of MNA. Under the same conditions the corona poling techniqu
e creates a higher alignment of molecules along the field direction. T
he time dependence of the second harmonic intensity of the MNA/PMMA fi
lm prepared by the two techniques can be described by a Kohlrausch-Wil
liams-Watts stretched exponential. The temperature dependence of the d
ecay time constant is found to generally follow a modified Williams-La
ndel-Ferry (WLF) or Vogel-Tamann-Fulcher (VTF) equation. The glass tra
nsition temperature seems to be the single most important parameter fo
r determining the relaxation time tau(T).