Preparation and reactions of hydrophilic isocyanate micelles dispersed in water

We investigated the abnormal reaction behavior of NCO units in micellar hydrophilic isocyanate in water through titration, particle size, FT-IR spectroscopy and GPC and mechanical properties. Hexamethylene diisocyanate (HDI) allophanate was modified with methoxy polyethyleneglycol (MPEG), yielding novel hydrophilic isocyanate, which formed stable and homogeneous micelles in water. The results we obtained showed that the rapid reduction of the NCO group took place at a specific time (with an induction period) after dispersing hydrophilic isocyanate into water. The induction period, which is equal to the lifetime of the NCO group, was largely dependent on the diameter of micelles determined by the content of MPEG introduced. The result of GPC measurement indicated that there are three types of reactions between NCO groups and water. The rapid reduction of NCO in water was explained by the stepwise progress of the reactions, according to the location of NCO units in the core-shell structure of hydrophilic isocyanate micelles.