Correlation between the polymerization kinetics and the chemical structure of poly(urethane–urea) nanocapsule membrane obtained by interfacial step polymerization in miniemulsion

Kinetics of the interfacial step polymerization in direct miniemulsion between 1,6-hexanediol and isophorone diisocyanate, at different temperatures and with different organic solvents as dispersed phase was investigated. Despite the complexity of the reaction system due to the specific experimental conditions, the profiles of consumption of the isocyanate groups and diisocyanate monomer, and the chemical structure of the being formed polymer membrane, were concurrently determined by gas chromatography, FTIR spectroscopy, 13C NMR and MALDI-TOF mass spectrometry. The results were connected with the key-steps of the membrane formation by interfacial polymerization, pointing out the prevailing influence of the organic dispersed phase on the hydrophilic monomer diffusion and the swelling rate of the polymeric membrane.

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► Poly(urethane–urea) nanocapsules prepared by interfacial step polymerization in miniemulsion.
► Determination of NCO groups and IPDI free molecules conversion rates.
► Study of the chemical structure by 13C NMR and MALDI-TOF versus reaction time.
► Three specific kinetics profiles according to the membrane formation stages.