Phenylene ring dynamics in phenoxy and the effect of intramolecular linkages on the dynamics of some engineering thermoplastics below the glass transition temperature

We have investigated the dynamics of phenylene rings in the engineering thermoplastic bisphenol-A poly(hydroxyether)—phenoxy—below its glass transition temperature by means of neutron scattering techniques. A relatively wide dynamic range has been covered thanks to the combination of two different types of neutron spectrometers, time of flight and backscattering. Partially deuterated samples have been used in order to isolate the phenylene ring dynamics. The resulting neutron scattering signal of phenoxy has been described by a model that considers π flips and oscillation motions for phenylene rings. The associated time scales are broadly distributed with mean activation energies equal to 0.41 and 0.21eV, respectively. Finally, a comparative study with the literature shows that the dielectric and mechanical γ relaxation in phenoxy exhibit good correlation with the characteristic times of the aliphatic chain published elsewhere and with the characteristic times observed for the motion of phenylene rings by neutron scattering. These findings are discussed in a more general framework that considers, in addition, previous results on other polymers, which also contain the bisphenol-A unit.We acknowledge “Donostia International Physics Center,” and the funding support of the following research projects: Project No. MAT 2004/01017 and Project No. 9/UPV00206.215-13568/2001.Peer reviewe