Bis(ether anhydride)s with 3- or 4-phthalimide moieties were prepared by reacting 3- or 4-nitrophthalodinitrile, respectively, with several diols and converting the resulting bis(ether dinitrile)s to bis(ether anhydride)s. Selected dianhydrides were converted into poly(ether imide)s in a two-stage solution polymerization and imidization process. It was found that, in most cases, the dianhydrides with 4-phthalic anhydride units gave high-molecular-weight polymers with any of several aromatic diamines. In contrast, dianhydrides with 3-phthalic anhydride units gave, primarily, low-molecular-weight products. Examination of several low-molecular-weight products by electrospray-ionization mass spectrometry demonstrated that the products consisted of small oligomers, cyclic or linear according to the structure of the diamine. A series of high-molecular-weight polymers were prepared from 4,4‘-bis(4‘ ‘-aminophenoxy)biphenyl (BAPB) and each of several bis(ether anhydride)s with 3- or 4-phthalic anhydride units; the anhydrides had isopropylidine or hexafluoroisopropylidine units or ortho-methyl or ortho-tert-butyl substituents in the diol residues. These polymers were characterized in terms of their molecular weights and glass-transition temperatures. The gas permeabilities, positron annihilation, and dielectric relaxation behaviors of the polymers were investigated and their properties related to their molecular structures. Dielectric relaxation spectroscopy measurements indicate that, in this group of polymers, the rates of the local chain mobility are comparable and are able to facilitate gas diffusion. An apparent linear correlation between the permeation coefficients and free volume as determined by positron annihilation lifetime spectroscopy was observed with certain gases. Comparison of polymers with similar molecular structures indicated that isomeric polymers with 3- and 4-linked phthalimide units have similar properties and that the introduction of branched chains or fluorinated groups leads to an increase in the free volume and consequently increased permeability.

Broad band dielectric relaxation spectra are reported for some poly(ether imide)s based on 2,2‐bis[4′‐(3″,4″‐dicarboxyphenoxy)phenyl]hexafluoropropane dianhydride and 1,2‐bis(4‐aminophenyl) diamines derived from ethylene glycol oligomers of different specific lengths. Spectra were obtained over the temperature range −150–−20 °C and which covers the low temperature relaxation region for these materials. In the case of the polymer with no EO units, a single broad dipole relaxation feature is observed. The introduction of a single CH2CH2O unit significantly broadens the relaxation suggesting the existence of two separate relaxation processes. Increasing the number of EO units per repeat to 3 and 6, allows resolution of two relaxations processes; one due to an oscillatory–librational motion of the imide segment and the other to conformational changes involving the EO sequences. Analysis of the relaxation using the Havriliak‐Negami equation indicates that both processes deviate for the description of a simple dipole relaxation and indicate cooperativity of bond motion in the relaxation process. The ability of a polymer to change its packing density is reflected in changes in the relaxation spectra on annealing and changes in the value of the higher frequency limiting values of the permittivity. The activation energy for dipole reorientation ranges from a value of 34 kJ mol−1 for the relaxation of the dipole associated with the imide relaxation process to a value of 60 kJ mol−1 for the polymer containing 3 EO segments. In this latter polymer, system a lower activation energy process is observed with a magnitude of ∼15 kJ mol−1 associated with conformational changes of the aliphatic ether. © 2014 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2014, 52, 1326–1336

Broad band dielectric relaxation spectra are reported on a range of polymers created by varying the ether segment in a series of poly(ether imide)s. Changes in the structure allow the effects of steric constraints on the local conformational dynamics of the polymer chain to be explored. These changes have a significant effect on the glass transition temperatures of these polymers which range from 245 to over 420°C. In contrast, the low temperature dielectric relaxation behavior of these polymers is very similar and is attributed to cooperative local oscillatory—librational motions. Changes in the stereochemistry effect the amplitude, activation energy for the relaxation process, the packing chain density, and values of the high frequency limiting permittivity, ε∞′. This latter parameter is sensitive to the extent of dipole induced dipole and π‐π electron interactions and is influenced by the packing density. The magnitude of ε∞′ is a very important parameter in determining the suitability of poly(imide)s for electrical applications. The magnitude of ε∞′ increases with the density; however, deviations from this general trend are observed when large nonpolar groups inhibit the interaction of neighboring chains. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014, 131, 41191.