VIBRATIONAL ANALYSIS OF DERIVATIVES OF POLYPARAPHENYLENE

Some new conjugated polymers are the subject of extensive studies sinc e one found their ability to be used in the fabrication of light emitt ing diodes. For a purpose of optimization of such materials, a good kn owledge of their electronic properties is essential. Therefore, we hav e studied their optical properties by means of vibrational techniques. In this paper, we report on two derivatives of Polyparaphenylene : on e is an alkyl chain substituted PPP and the other is a deuterated ladd er polymer, which has a planar conformation. Both are soluble because of alkyl substitution on phenyl rings. We present off-resonance Raman spectra of both compounds in solid state and assign the different mode s with the help of dynamical calculations based on a valence force fie ld model. The force constants of the phenyl rings have been taken from calculations performed on PPP and a good agreement is obtained betwee n calculated and experimental data.