ABSTRACT
Quaternization and dequaternization of tertiary amines were employed to generate thermally reversible covalent ionene networks. Chlorine or tertiary amine containing polymers were cross-linked with ditertiary amines and dihalide compounds, respectively, to generate ionene networks. The cross-linking reactivity of the dihalide decreased with decreasing carbonium ion character of its alkyl, and the reactivity of the ditertiary amine was dependent on the steric effect of its alkyl groups and the flexibility of the alkyl connecting the two nitrogen atoms of its molecule. IR and NMR tests, reactive solubility experiments and conductivity, differential scanning calorimetry, and flowability (at 215°C) determinations have been carried out to investigate the thermal reversibility of cross-linked polymers. The thermal de-cross-linking/re-cross-linking was markedly affected by the nature of the tertiary amine and halide that took part in quaternization. Poor reversibility was found when the Cl-containing polymer was cross-linked with a diamine whose nitrogen atoms belonged to a saturated ring, such as dipiperidinomethane and 1,4-dimethylpiperazine. The de-cross-linking and re-cross-linking were rapid when either one or both bridging alkyls of the nitrogen atoms possessed a higher carbonium ion character than the two nonbridging alkyls. The (co)-polymers obtained through the (co)-polymerization of chloromethylstyrene, 2-(dimethylamino)ethyl acrylate, 196or vinylpyridine could be effectively quaternized with selected cross-linkers under moderate conditions to generate networks that exhibited thermal reversibility.
