The synthesis, morphology, and properties of segmented poly(ether amide)s based on flexible PTHF segments (M n = 1.1 × 103 g mol–1) and uniform rigid oxalamide segments were investigated. The amount of oxalamide groups in the hard segment and the spacer length of bisoxalamide-based hydrogen bonded arrays were varied systematically. The segmented poly(ether amide) with single oxalamide groups connecting the polyether blocks was a sticky solid with a melting temperature of ∼25 °C. Incorporation of uniform hard segments consisting of two interconnected oxalamide units provided highly phase-separated thermoplastic elastomers with a broad temperature-independent rubber plateau. By decreasing the aliphatic spacer length separating two oxalamide units from 10 to 2 methylene groups, the melting transitions increased from 140 to 200 °C. FT-IR evidenced strongly hydrogen bonded and highly ordered bisoxalamide hard segments with degrees of ordering between 66 and 90%. AFM revealed the presence of fiber-like nanocrystals with lengths up to several hundreds of nanometers randomly dispersed in the soft PTHF matrix. The long dimension of the crystals was found parallel to the direction of the hydrogen bonds. One of the other small dimensions of the crystal approximately equals the length of the oxalamide segment, whereas the other one may correspond to the height of a stack containing ca. 10–20 hydrogen-bonded sheets. Upon heating, the crystalline phase melts over a broad temperature range to give a homogeneous melt according to temperature-dependent FT-IR, SAXS, and rheology data. Increasing the number of oxalamide groups in the hard segment to three afforded a highly phase-separated material with a melting transition above 200 °C. The segmented copolymers with two or three oxalamide groups in the hard segment show a distinct yield point and have an elastic modulus between 121 and 210 MPa, a stress at break ranging from 15 to 27 MPa, and strain at break of 150 up to 900%. The results demonstrate that alternating block copolymers with soft PTHF segments and uniform hard segments containing two or three oxalamide groups are TPEs with good thermal and mechanical properties.

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Polyether polyols are often used in formulated systems, but their complete characterization is challenging, because of simultaneous heterogeneities in chemical composition, molecular weight and functionality. One-dimensional liquid chromatography-mass spectrometry is commonly used to characterize polyether polyols. However, the separation power of this technique is not sufficient to resolve the complexity of such samples entirely. In this study, comprehensive two-dimensional liquid chromatography hyphenated with high-resolution mass spectrometry (LC × LC-HRMS) was used for the characterization of (i) castor oil ethoxylates (COEs) reacted with different mole equivalents of ethylene oxide and (ii) a blended formulation consisting of glycerol ethoxylate, glycerol propoxylate and glycerol ethoxylate-random-propoxylate copolymers. Retention in the first (hydrophilic-interaction-chromatography) dimension was mainly governed by degree of ethoxylation, while the second reversed-phase dimension resolved the samples based on degree of propoxylation (blended formulation) or alkyl chain length (COEs). For different COE samples, we observed the separation of isomer distributions of various di-, tri- and tetra-esters, and such positional isomers were studied by tandem mass spectrometry (LC-MS/MS). This revealed characteristic fragmentation patterns, which allowed discrimination of the isomers based on terminal or internal positioning of the fatty-acid moieties and provided insight in the LC × LC retention behavior of such species.