Study of the kinetics of the pancake-to-brush transition of poly(N-isopropylacrylamide) chains.
The chemical grafting of thiol-terminated poly(N-isopropylacrylamide) (HS-PNIPAM) chains to a gold surface from a solution was investigated with a quartz crystal microbalance (QCM) in real time. The frequency and energy dissipation responses revealed that short HS-PNIPAM chains exhibit three-regime kinetics of the grafting. In regimes I and II, the HS-PNIPAM chains form pancake and mushroom structures, respectively. In regime III, the chains form brushes. From regime II to regime III, the mushroom-to-brush transition occurs. For the longer HS-PNIPAM chains, because of the strong segment-surface interaction, the segments cannot desorb from the surface, and the chains do not undergo a pancake-to-brush transition.
Liu
Guangming
G
Hefei National Laboratory for Physical Sciences at Microscale, Department of Chemical Physics, University of Science and Technology of China, Hefei, Anhui, China.
Cheng
He
H
Yan
Lifeng
L
Zhang
Guangzhao
G