Effect of Structural Parameters on the Supramolecular Organization of Rigid-Flexible Polymers Dedicated to Prof. G. Wegner on the occasion of his 65 th birthday Benjamin Carbonnier, 1 Aikaterini K. Andreopoulou, 2 Tadeusz Pakula,* 1 Joannis K. Kallitsis* 2 1 Max-Planck-Institute for Polymer Research, Postfach 3148, 55021 Mainz, Germany E-mail: pakula@mpip-mainz.mpg.de 2 Department of Chemistry, University of Patras, GR-265 00 Patras, Greece, and Foundation for Research and Technology-Hellas, Institute of Chemical Engineering and High Temperature Chemical Processes, P.O. Box 1414, GR-265 00 Patras, Greece Fax: 0030-2610-997 122; E-mail: j.kallitsis@chemistry.upatras.gr Received: May 17, 2004; Revised: October 15, 2004; Accepted: October 19, 2004; DOI: 10.1002/macp.200400202 Keywords: dendrimers; polyethers; self-organization; structure-property relations; supramolecular structures Introduction Oligomeric or polymeric materials composed of various structural units incompatible with each other, have been considered as a very promising combination for the forma- tion of interesting, architectural patterns. This kind of imposed anisotropy into a macromolecular system has already been taken advantage of in a number of reports, indeed providing materials with different organizational characteristics depending on the detailed monomers’ chem- ical identity and on their arrangement, regular or not, into the final polymeric chain. [1–3] Alkoxy-group bearing aromatic polymers have been designated as a large area of such macromolecular systems. More particularly, alkoxy-substituted polymers show a significant tendency towards self-organization in a supramolecular level starting from the ‘‘hairy-rod’’ poly- mers, where the lateral attachment of alkoxy-substituents onto a rigid or semi-rigid polymeric backbone resulted in the formation of layered structures with different char- acteristics depending on the length of the side chains and the substitution density. [4–8] Additionally, alkoxy periphery decorated dendrons and dendrimers have revealed assemblies formed due to the Summary: Rigid-flexible polyethers consisting of terphenyl and aliphatic segments of various lengths along their main chains and disubstituted by dendritic wedges of various generations (G 0 ,G 1 , and G 2 ) are examined in their bulk states. Characterization of phase transitions has been performed by means of differential scanning calorimetry (DSC) and was supported by structural information obtained from small- angle light scattering (SALS) and polarized optical micro- scopy (POM) experiments. In order to characterize order on the molecular size scale, two-dimensional (2D) wide-angle X-ray diffraction (WAXS) experiments have been performed for macroscopically oriented samples. All results pointed out a highly ordered nature of these materials. Both monomers and polymers were characterized. In the case of polymers, structures consisting of layered backbone sheets separated by the side dendritic moieties filling the space between them were deduced. In all cases, strong effects of molecular para- meters, such as main chain flexible spacer’s length and sizes of substituents, on transition temperatures (odd-even effect), degree of orientation, and distances characteristic for the supramolecular structures, were observed. Example of 2D X-ray diffraction patterns recorded for oriented films of the polymers PETH-(2OC 12 H 25 ) (the zero generation). Macromol. Chem. Phys. 2005, 206, 66–76 DOI: 10.1002/macp.200400202 ß 2005 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim 66 Full Paper