Kinetics of the Adsorption of a PDMS-g-PEO Copolymer at the PDMS/PEO Interface

The kinetics of interface formation between poly(dimethylsiloxane) (PDMS) and poly(ethylene oxide) (PEO) with and without low molecular weight copolymer PDMS-g-PEO has been studied by interfacial tensiometry. For the PDMS/PEO interface, interfacial tension is constant with time and the interface is immediately formed. For the PDMS/PEO interface with copolymer, interfacial tension decreases slowly or goes to a minimum (unexpected) with time before reaching its equilibrium value, depending on copolymer concentration in the PEO. This kinetics of interface formation with an overshoot has been explained with two processes: adsorption of the copolymer at the interface by transfer over an energy barrier and relaxation of the interfacial layer.