Homopolymerization Of Cation-type Surface Active Monomer AMC₁₄AB And P(AMC₁₄AB) Micellization Behaviour Of Unimolecular Micelles

Cation-type Surface active monomer of (2-acrylamido)ethyltetradecyldimethyl ammonium bromide(AMC14AB)was synthesized by using acrylic acid, N,N-dimethyl ethylenediamine and bromotetradecane as main raw materials, and its chemical structure was characterized with FTIR and 1H-NMR. The solubility of AMC14AB was determined by UV spectrophotometry, and the critical micelle concentrations at different temperatures were measured at the same time by using two methods, surface tension and conductivity measurements. The experiment results show that the Krafft temperature of AMC14AB is 21.3℃, its critical micelle concentration (CMC) is 6.51×10-4mol·L-1 at 25℃, and the corresponding surface tensionγCMC is 46.3mN·m-1 which displays that AMC14AB possesses higher surface activity.The polymerization kinetics of (2-acrylamido)ethyltetradecyldimethylammonium bromide (AMC14AB) in aqueous solution has been studied with KBrO3-KBr method.The effects of initiator concentrations,monomer concentrations and temperature on kinetics of AMC14AB polymerization in aqueous solutions have been studied,the polymerization rate equation was determined ,and the polymerization active energy was measured.,at the same time the polymerization mechanism was shown ; The research indicated that the polymerization rate equation for AMC14AB is which displays that the chain termination reaction is according to the bimolecular mode, and the intitate process is independent on monomer concentration,and the apparent polymerization active energy is 80.72 kJ/mol. The reaction mechanism can explain the ploymerization process correctly.The Homopolymer of a cationic surface-active monomer(,2-acrylamido)ethyl tetradecyl dimethylammonium bromide (AMC14AB), was prepared through aqueous solution polymerization, and the homopolymer P(AMC14AB) was obtained. Besides, the critical micelle concentrations of AMC14AB do not change nearly with temperature ; the micellization behaviour in aqueous solution and surface adsorption on solution surface for P (AMC14AB) were mainly examined by using fluorescence probe method, surface tension measurement and conductometry. In aqueous solution, homopolymer P(AMC14AB) exists as monomolecular micelles and has zero critical micellar concentration (CMC=0), and once P(AMC14AB) is added into water, monomolecular micelles form immediately. There is no Krafft temperature for P (AMC14AB). The adsorption phenomenon of P (AMC14AB) on solution surface also takes place, and leads to the decrease of surface tension. In the beginning, the surface adsorption amount of P (AMC14AB) increases and the surface tension decreases continuously with the increase of concentration. When the surface adsorption gets up to saturation, a turning point will appear on the curve of surface tension vs concentration. This point should be termed as"saturated surface adsorption concentration", instead of critical miccelar concentration. The solubilization of the monomolecular micelles for hydrophobic organic substances is different from multiple-molecule micelles of common surfactants, and there is no mutational site on the curve of the solubilization amount of toluene vs P(AMC14AB) concentration. Moreover, the ability to solubilize toluene for the monomolecular micelles solution of P (AMC14AB) is higher than that of the multiple-molecule micelles solution of common surfactant cetyl trimethyl ammonium bromide(CTAB).