Print Email Facebook Twitter Molecular Arrangement and Thermal Properties of Bisamide Organogelators in the Solid State Title Molecular Arrangement and Thermal Properties of Bisamide Organogelators in the Solid State Author Ghanbari, E. (TU Delft ChemE/Advanced Soft Matter) Krishnamurthy, Aravind (Student TU Delft) Picken, S.J. (TU Delft ChemE/Advanced Soft Matter) Klop, Enno A. (Teijin Aramid Research and Innovation Centre, Arnhem) Bannenberg, L.J. (TU Delft RID/TS/Instrumenten groep) van Esch, J.H. (TU Delft ChemE/Advanced Soft Matter) Date 2022 Abstract The crystal structure and phase behavior of bisamide gelators are investigated using differential scanning calorimetry (DSC), Fourier transform infrared spectroscopy, X-ray diffraction (XRD), and molecular modeling, aiming at a better understanding of bisamide gel systems. A homologous series of bisamide model compounds (nBAs) was prepared with the (CH2)nspacer between the two amide groups, where n varies from 5 to 10, and with two symmetric C17 alkyl tails. With increasing spacer length, the thermal properties show a clear odd-even effect, which was characterized using our newly developed analytical model DSCN(T). Using XRD, all studied nBA compounds turn out to have a layer-like structure. The XRD patterns of the odd BA series are very similar but show marked differences compared to the XRD patterns of the even series, which in turn are very similar. The odd-membered 5BA molecules are nearly perpendicular to the stacked layers, as described by a pseudo-orthorhombic unit cell, whereas the even-membered 6BA molecules are tilted at an angle with respect to the layer normal, as described by a triclinic unit cell. In both the odd and even series, the inter-layer interaction is the van der Waals interaction. The 6BA hydrogen bonding scheme is very similar to that of Nylon 6,10 α, unlike the 5BA H bonding scheme. The packing of the C17 alkyl tails in the 5BA layers is similar to polyethylene, and unlike 6BA. The slightly higher crystalline density of 6BA (1.038 g cm-3) as compared to 5BA (1.018 g cm-3) explains the higher melting point, higher enthalpy of fusion, and the observed shift of N-H stretch bands to higher wave numbers. The structural differences observed between the odd and even BA series reflect the different structure-directing effect of parallel versus antiparallel amide hydrogen bonding motifs. These differences underlie the observed odd-even effect in the thermal properties of nBA compounds. To reference this document use: http://resolver.tudelft.nl/uuid:9961c543-4fef-4e81-9904-ed300c8a2fc5 DOI https://doi.org/10.1021/acs.langmuir.2c02679 ISSN 0743-7463 Source Langmuir: the ACS journal of surfaces and colloids, 38 (50), 15782-15795 Part of collection Institutional Repository Document type journal article Rights © 2022 E. Ghanbari, Aravind Krishnamurthy, S.J. Picken, Enno A. Klop, L.J. Bannenberg, J.H. van Esch Files PDF acs.langmuir.2c02679.pdf 6.62 MB Close viewer /islandora/object/uuid:9961c543-4fef-4e81-9904-ed300c8a2fc5/datastream/OBJ/view