Structure Development in Flexible Polyurethane Foam‐Layered Silicate Nanocomposites

Summary: Polyurethane foam nanocomposites were formed via in‐situ copolymerisations, in which polyether polyol/water‐montmorillonite mixtures were reacted with toluene diisocyanate. The unmodified Na + ‐ montmorillonite (MMT) was swollen in polyol/water using an ultrasound technique resulting in intercalated layers with increased basal spacings of 2.3 ± 0.1 nm. Measurements of quasi‐adiabatic temperature rise showed higher reaction rates as MMT loading increased from 0 to 10 wt.‐%. Forced‐adiabatic FTIR spectroscopy was used to determine the kinetics of both the copolymerisation and of the microphase separation between poly(ether‐urethane) soft segments and polyurea hard segments. The apparent microphase‐separation transition time decreased from 70 ± 3 to 42 ± 2 s upon addition of ≤10 wt.‐% MMT, but at reaction times >100 s there was significant retardation of the development of hydrogen bonding in the urea groups of the hard‐segment phase.