Non-covalent assembly of poly(allylamine hydrochloride)/triethylamine microcapsules with ionic strength-responsiveness and auto-fluorescence

Ionic strength-responsive microcapsules with auto-fluorescence were fabricated by incubation of poly(allylamine hydrochloride) (PAH)-doped CaCO 3 particles in triethylamine (Et 3 N), followed by core removal using HCl. Based on the combination of hydrophobic interaction and hydrogen bonding , PAH and Et 3 N formed a complex with a molar ratio of 3:1 (repeating unit of PAH: Et 3 N). The as-prepared capsules showed extraordinary stability against 1   M HCl, 1   M NaOH and 6   M urea solutions, and could swell or shrink reversibly in response to the ionic strength. Furthermore, the capsules possessed auto-fluorescence, allowing easily tracking of capsules during applications. Such interaction may be expanded to formation of stimuli-responsive multilayer films and other colloidal particles.