G. Floudas et al., Dielectric relaxation in poly(styrene-b-butadiene) copolymers with perfluorinated side chains, J CHEM PHYS, 113(8), 2000, pp. 3447-3451
The dynamics of several poly(styrene-b-butadiene) (PS-PB) copolymers with f
luorocarbon side chains have been studied with dielectric spectroscopy, cov
ering two different mesophases with long spacings between 10 and 30 nm, and
two different tail lengths. It is found that fluorination results in compa
rably rigid side chains in the PB domains with highly anisotropic propertie
s. In the glassy state an Arrhenius relaxation was found with an activation
energy of 7.4 kcal/mol reflecting some local side chain relaxation. Above
the PB glass transition a bimodal relaxation exists, comprising two coopera
tive processes reflecting solely the anisotropic dynamics of the side chain
. The dual relaxation resembles the anisotropic dielectric properties of si
de chain liquid crystalline polymers in the absence of macroscopic orientat
ion. (C) 2000 American Institute of Physics. [S0021-9606(00)50832-0].