Poly(N-isopropyl acrylamide) (PNIPAM) is a thermoresponsive polymer with a bulk lower critical solution temperature (TC) of ?32 ? in water A few recent studies explored the effect of confinement on the solution behavior of PNIPAM. Specifically, the phase transition behavior of surface-grafted PNIPAM was inferred from wettability changes, thickness measurements using surface-plasmon resonance, neutron reflectivity4 and quartz crystal microbalance techniques. While PNIPAM is not a polyelectrolyte, previous studies7-9 performed on bulk PNIPAM solution, revealed that due to the Hofmeister effect, increase in concentration of salt in water caused shifts in the solution TC. In this work we use quartz crystal microbalance with dissipation monitoring (QCM-D) to examine the effect of temperature and ionic strength on TC of PNIPAM brushes grafted on a solid substrate. The initial experimental results reveal that QCM-D is a powerful tool capable of probing minute changes in the brush conformation.
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