Formation of molecular membranes in water from ionene oligomers and related amphiphiles

Abstract

Ionenes were prepared by reaction of α,ω-dibromoalkanes and α,ω-bis(dimethylamino)alkanes at room temperature. The degree of polymerization as estimated from NMR data was 2 to 5. The oligomeric ammonium amphiphiles (ionenes) thus obtained gave molecular weights of 105 to 108 in water. Vesicles of the molecular membrane were formed by self-assembly of the C20 ionene. A related bis-ammonium amphiphile gave similar results. The introduction of symmetrical aromatic rings into the middle of the C20 chain did not change the general aggregation behavior. Differential scanning calorimetry indicated the presence of gel-to-liquid crystal phase transition in these cases. No membrane formation was observed when the methylene chain length was shorter (C10 and C12) or the two methylene portions were uneven in length (C20 and C16). © 1985 The Society of Polymer Science, Japan.