Adsorption of PEO-PPO-PEO triblock copolymers at the solid/liquid interface: A surface plasmon resonance study

Poly(ethylene oxide)-poly(propylene oxide)-poly(ethylene oxide) (PEO-PPO-PEO) triblock copolymers are used in a wide range of industrial applications from detergents to pharmaceutical materials. We have employed surface plasmon resonance (SPR) to monitor the adsorption of these materials, from aqueous solutions to a model hydrophobic surface. The effect of varying the PPO or PEO block size of the copolymer on adsorption has been investigated, and a linear increase in SPR angle shift with increasing PPO or PEO chain length is observed. The SPR angle shifts show a greater increase in SPR angle with increasing PPO block size compared to an equivalent increase in PEO block size. This has been explained by considering the effect each block has on the dielectric properties of the adsorbed polymer at the interface. The presence of micelles in solution and their influence on Pluronic adsorption has also been considered, and adsorption from micellar solutions has been determined to be dependent on the PPO content of the copolymer.