Segmented Poly(tetramethylene oxide) Zwitterionomers and Their Homologous Ionenes. 1. Synthesis, Molecular Characterization, and Thermal Stability
Résumé
The synthesis of segmented poly(tetramethylene oxide) (PTMO) zwitterionomers and their homologous ionenes was achieved through a multistep strategy involving (i) polyaddition of living bifunctional monodisperse PTMO chains (THF/(CF3SO2)2O/20 °C, ~ (2–7) × 103) over diamines (CH3)2N(CH2)xN(CH3)2 (x = 2, 3, 6) or α,ω-dimethylamino-PTMO to yield segmented PTMO ionenes with fairly high degrees of chain extension (, ~ 20–170), (ii) quantitative exchange of the triflate anion on the ionene by propanesulfonate (CH3(CH2)2SO3 –) and ethoxydicyanoethenolate (C2H5OCOC–(CN)2) anions, (iii) quasi-quantitative and selective demethylation of the original ionene (LiEt3BH in THF at 50 °C, demethylation selectivity s = 0.97 ± 0.01) to yield tertiary amino segmented PTMO with only weak chain degradation, and (iv) quantitative functionalization of the tertiary amino polymeric precursor into the zwitterionomers of the ammonioalkanesulfonate (N+(CH2)pSO3 –, p = 3, 4) or (ammonioalkoxy)dicyanoethenolate (N+(CH2)pOCOC–(CN)2, p = 2, 3) type. For all the functionalized polymers, weight loss under nitrogen does not occur below 200 °C, and the thermal stability of the zwitterionic structure at 130 °C over long periods (24 h) is well ascertained. Because of the good control of their structural parameters, these tailor-made segmented PTMO should allow a comprehensive analysis of the typical microphase separation of the hard dipolar units within the soft PTMO matrix as a function of their structure (dipole moment, bulkiness, comparison between zwitterions and ion pairs) and of their density along the chain. © 1995, American Chemical Society. All rights reserved.