Molecular Design and Polymer Structure Control Based on Polymer Crystal Engineering. Topochemical Polymerization of 1,3-Diene Mono- and Dicarboxylic Acid Derivatives Bearing a Naphthylmethylammonium Group as the Countercation

The topochemical polymerization of the alkylammonium salts of (Z,Z)-, (E,Z)-, and (E,E)-1,3-diene mono- or dicarboxylic acids, i.e., of the muconic and sorbic acid derivatives, is described from the viewpoint of polymer crystal engineering. Not only the (Z,Z)- but also the (E,E)-derivatives polymerize to give a high molecular weight polymer in the crystalline state under UV irradiation when a naphthylmethylammonium moiety is introduced to these monomers as the countercation. NMR spectroscopy confirms the formation of the stereoregular meso- or erythro-diisotactic-trans-2,5-polymer during the polymerization, irrespective of the configuration of the monomers and the structure of the substituents. The single-crystal structure analysis of the naphthylmethylammonium salt of sorbic acid reveals the stacking of the diene moieties in the columns formed in the crystals, favorable for the topochemical polymerization. The photopolymerization reactivity and the stereochemistry of the resulting polymers are determined by the molecular packing in the crystals during the topochemical polymerization of the diene monomers.