Abstract
Perturbations in typical dielectric or calorimetric features of the molecular relaxation dynamics in amorphous poly(methyl methacrylate) and two blends with a neutral/apolar brominated perylene dye were analyzed to explore guest-host nanoscale interactions and their role on lasing properties. Aside from a gradual increase of the relaxation strength Δεβ (plasticization), the local β relaxation is nearly independent of the presence of dye. By contrast, segmental dynamics are moderately hampered: both the dielectric (Tα) and calorimetric (Tg) estimates of the glass transition temperature rise with increasing dye content, probably as a result of modifications in the free volume (antiplasticization). Analogous shifts are observed in the peak temperature of the space-charge relaxation (Tρ) and the α′ (liquid-liquid) transition (TLL), with Tρ∕Tα=1.04±0.01 and TLL∕Tα=1.10±0.01.
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