{
    "protocol": "The PAMPS gel was synthesized by radical polymerization. An aqueous solution of 1.0 M 2-acrylamido-2-methyl-1-propanesulfonic acid (AMPS), 5.0 mol% cross-linking agent, N,N'-methylenebisacrylamide (MBAA), and 0.1 mol% initiator, 2-oxoglutaric acid, was prepared in the reaction cell, purged with nitrogen gas for 30-45 min, and irradiated with UV light for 5 h at 20 °C. The reaction was conducted between a pair of polystyrene substrates or glass substrates, separated by a 2 mm thick spacer. After polymerization, the gel was immersed in a large amount of water for 1 week to equilibrate and wash away residual chemicals. The swollen PAMPS gels were cut into square shapes of 1.0 x 1.0 cm² for friction measurement using a rheometer with a coaxial two parallel planar geometry. The average frictional force was calculated from the torque detected as the lower platen rotated in water at 25 °C."
}