Polyionene bilayer vesicles

Abstract

3-Bromopropyldialkylamine hydrogen bromide of different alkyl groups could be synthesized from 3-aminopropanol by reacting first with alkyl halide, and then with $PBr_3$. Other substituted dialkylamine salts including hexyl, undodecyl, ethoxyethyl, ethoxyethoxyethyl derivatives were also prepared according to the similar method. Most of the amine salts mentioned above could be dispered by forming vesicles in water by sonication or vortex mixing, but failed to polymerize. Polymeric vesicle dispersion by ultra-sonic irradiation were obtained only in the case of 3-bromopropyldialkyl-amine salts even though the molecular weights were low. During the dispersion process of 3-bromopropyl-didodecylamine hydrogen bromide, coded as BPDH, dispersed in water by ultra-sonic irradiation, oligomerization of BPDH also took place in vesicle form. The polymerization was probably facilitated by amphiphilic aggregation. The pH of thus obtained dispersion was then adjusted to 10 with 1.0 M NaOH. And the resulting dispersion was again sonicated for polymerization through quaternization. The pH of the polymeric dispersion thus obtained was 8.2-8.6 indicating that the quaternization of amines had taken place. Electron micrographs confirmed the presence of closed vesicles of polymeric BPDH having diameters ranging between 300 and $1400 \mbox{\AA}$. The vesicles are mostly multi-lamellae of bilayers of ca. $50 \mbox{\AA}$ width. Polymeric BPDH gave well developed multi-walled vesicles compared with monomeric analogue 3-bromopropylmethyldidodecylammonium bromide (BDMA). Further evidence for closed vesicles comes from the entrapment of [$14_C$] sucrose. The amount of [$14_C$] sucrose entrapped into vesicles of polymeric BPDH were about 2\%. It was also confirmed by electron micrographs that other amphiphiles formed vesicles. And chromatograms of GPC showed the lyophilized BPDH possess oligomeric structures. Lyophilized polymeric product was quite different in solubility compared with BPDH...