CONJUGATED IONIC POLYACETYLENES .8. AMPHIPHILIC POLY(N-OCTADECYL-2-ETHYNYLPYRIDINIUM BROMIDE)

An amphiphilic, ionic, conjugated polymer, poly(N-octadecyl-2-ethynylp yridinium bromide) (PNO2EPB), was prepared by two different synthetic processes. One involved a direct reaction of 2-ethynylpyridine (2EPY) with 1-bromooctadecane (1-BO), the other involved quaternization of th e uncharged poly(2-ethynylpyridine) (P2EPY) with 1-BO. A fully quatern ized PNO2EPB homopolymer was produced in the former reaction, but a co polymer of 2EPY and N-octadecyl-2-ethynylpyridinium bromide (NO2EPB) w as obtained in the latter due to partial quaternization of P2EPY. The structure and properties of these polymers were investigated. The stud y of PNO2EPB formation using differential scanning calorimetry and ult raviolet-visible spectrophotometry indicated that quaternization of 2E PY monomer by 1-BO preceded polymerization of quaternized 2EPY monomer . Fully quaternized PNO2EPB displays a longer conjugation length and a n enhanced thermal stability compared with the partially quaternized P 2EPY-q-octa and the non-quaternized P2EPY. The study of compression is otherms of monolayers of the fully quaternized polymer leads to the co nclusion that the alkyl (octadecyl) chains of the repeating unit are p erpendicular to the water interface while the conjugated polymer chain s are in the plane of the interface. Copyright (C) 1996 Elsevier Scien ce Ltd.