Poly{2-vinyloxyethyl 3,4,5-tris[4-(n-dodecanyloxy)benzyloxy]benzoate}: a self-assembled supramolecular polymer similar to tobacco mosaic virus

Abstract

The synthesis of 2-vinyloxyethyl 3,4,5-tris[4-(n-dodecanyloxy)benzyloxy]benzoate (3), its cationic polymerization to poly{2-vinyloxyethyl 3,4,5-tris[4-(n-dodecanyloxy)benzyloxy]benzoate}(4) with relative number-average degrees of polymerization (DP) from 3.7 to 16 and narrow molecular-weight distributions (i.e. M_w/M_n⩽ 1.28), and the characterization of 4 by a combination of techniques consisting of differential scanning calorimetry, thermal optically polarized microscopy, and X-ray scattering experiments are presented. Regardless of molecular weight, compound 4 displays an enantiotropic columnar hexagonal (Φ_h) mesophase and an enantiotropic nematic (N) mesophase. The structural unit of 4 has a tapered shape. At low DP values (i.e. DP ⩽ 4) the tapered side-groups of 4 self-assemble into a disc-like supramolecular architecture which generates the Φ_h and the N mesophases. At DP ⩽ 4, 4 self-assembles directly into a column-like supramolecular architecture In this last case the backbone of the polymer penetrates through the middle of the column from which the tapered side groups are radiating out to the edge of the column. It is believed that the disc-like and column-like supramolecular architectures exist in the Φ_h, N, and the isotropic phases except that in the last one the structure lacks long-range positional order. The mechanism of self-assembly of 4 resembles that of the tobacco mosaic virus (TMV) except that in the first case the tapered side groups are linked to the polymer backbone via covalent bonds and in the latter case via non-covalent bonds.