G. Petekidis et al., ORIENTATION FLUCTUATIONS IN CONCENTRATED-SOLUTIONS OF HAIRY-ROD POLYMERS, Colloid and polymer science, 272(11), 1994, pp. 1457-1465
Photon correlation spectroscopy in the depolarized geometry was employ
ed to measure the orientation relaxation correlation function C(q,t) i
n poly(p-2,5-dodecyl-1,4-phenylene)/toluene solutions at different sca
ttering wavevectors q. The large optical anisotropy of this hairy rod
molecule with an average length L = 117 nm allowed a detailed analysis
of both amplitude and shape of C(q,t) that revealed two mechanisms fo
r relaxing the orientation fluctuations in the concentrated regime (10
< cL(3) < 230). The comparison of the rotational diffusivity and the
anisotropic scattering intensity with theoretical, simulation and expe
rimental results of rigid rods indicated quantitatively different beha
vior for the present stiff-chain bearing two long side groups per repe
ating unit.