The reaction of tetrafunctional diamines and bifunctional amines with monoepoxy compounds was investigated by gel‐permeation chromatography. At a stoichiometrically equivalent ratio of the functional groups or excess of amine, the consecutive reaction of the epoxide groups with the hydrogen atoms of the amino groups is the only reaction that is taking place; if epoxide is present in excess, the OH groups formed in the reaction are gradually added to the epoxide groups. The ratio of the rate constants of the reaction of the epoxy group with the hydrogen atoms of the primary and secondary amino group was calculated from the concentrations of the reaction products at various excess amounts of amines. The ratio is in good accord with the value calculated from the gel points and limiting stoichiometric ratios in the curing of diepoxides with diamines.
The curing of epoxy resins with amine curing agents has been statistically treated as irreversible alternating polyaddition with the aid of the theory of cascade processes for cases when the polymerization of epoxy groups and cyclization are negligible. The coefficients of vectorial generating functions are obtained by solving kinetic differential equations. The solution has been carried out for the reaction of diepoxide with diamine with an independent reactivity of epoxy groups in diepoxide and amino groups in diamine, but with a different reactivity of hydrogen atoms in the primary and secondary amino group. Relationships have been derived for changes in the molecular weight averages, in the sol and gel fractions and their composition, and in the concentration of elastically active network chains as a function of conversion. The conditions for the gel point have been determined. The structural parameters depend on the ratio of the rate constants of hydrogen atoms in the primary and secondary amino group, k2/k1 = r, and on the stoichiometric ratio of functionalities. In a stoichiometrically equivalent system the critical conversion at the gel point increases from 1/2 for r → oo up to (1/2) (51/2 – 1) for r → 0. The critical stoichiometric ratio for gel formation at full conversion of (epoxide) functionalities in deficiency is < 3 or > 3 for r < 1 or r > 1, respectively.
Four different derivatives of diphenyl-diketo-pyrrolopyrrole (DPP) with alkyl side groups were synthesized to increase their solubility. Quantum chemical calculations revealed that the substitution influenced molecular geometry and subsequently modified absorption and photoluminescence spectra. The theoretical results were confirmed by experimental characterization. With increasing phenyl torsion the vibrational structure was less pronounced and larger Stokes shift was observed. Simultaneously, the molar absorption coefficient decreased as the deformation increased. On the other hand, the measured fluorescence quantum yields were modified only slightly. This indicates the possibility to prepare soluble derivatives without loss of quantum yields and to use these materials for construction of efficient and stable electroluminescent devices. Furthermore, the electroluminescence of the thin layer devices based on the soluble low molecular DPPs were characterized and discussed.
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