Dendronized Rigid−Flexible Macromolecular Architectures:  Syntheses, Structure, and Properties in Bulk

Side-chain dendronized polymers consisting of regularly segmented alternating rigid−flexible main-chain units and side dendritic wedges are synthesized and analyzed in their bulk state using various experimental methods. High molecular weight polymers were obtained in most cases enabling the formation of self-supporting films. The thermal and mechanical characterization of these polymers, by means of DSC and dynamic mechanical analyses, has revealed a highly ordered nature, which was further supported from SALS and POM experiments. Additionally, their transition temperatures seem to strongly depend on the main-chain flexible spacer's length, in a manner resembling the odd−even effect. The existence of organizational features in both isotropic and macroscopically oriented samples was concluded for these polymeric materials due to the intense and well-resolved diffractions in their WAXS patterns. From qualitative analyses of the WAXS patterns corresponding to oriented filaments, the development of layered structures is postulated, comprised of main-chain polymeric backbones while the side dendrons occupy the space between the layers. Actually, two types of LC ordering for the extended backbones within the main-chain layers could be distinguished. In general, the exact polymeric structure, side-dendrons' generation and main-chain flexible spacers' length, greatly influence the final polymeric properties, such as phase transitions and structural parameters.