Molecular mobility in comb‐like copolymethacrylates with chalcone‐containing side‐chains

The molecular mobility of comb‐like copolymers of amyl methacrylate with N‐methacryloyl‐(4‐amino‐4′‐bromochalcone) with various concentrations (20, 30, 40, 50 and 60 mol%) of chalcone‐containing comonomer was studied using dielectric spectroscopy. It was found that chalcone chromophores participate in two forms of molecular mobility: cooperative motion in the rubbery state (δ‐relaxation) and local motion in the glassy state (β‐relaxation). In addition, α‐, β₁‐ and γ‐processes, being related to cooperative segmental mobility, to local motion of ester groups adjacent to the backbone and to local motion of terminal side‐groups, respectively, were evident. The molecular mobility of the β₁‐, β‐ and γ‐processes changed slightly with the concentration of chromophore groups. For the δ‐ and α‐processes, the glass transition temperatures, T_δ and T_g, increased with the molar fraction of chalcone groups, the difference between them remaining nearly constant (ca 55 °C). The T_δ values obtained should be considered as optimal temperatures for the corona‐poling of the chromophore‐containing polymers for the preparation of second‐order nonlinear optical polymer films with non‐centrosymmetric arrangement of chromophore groups. Copyright © 2011 Society of Chemical Industry