Amino silane electroosmosis
Membrane chips were amino-silanized with APTES in the YES system. I performed the standard electroosmosis tests with these chips. Here are the flow rates in comparison with non treated and oxidized membranes:
Here are the calculated zeta potentials:
As you can see, amino silane reduces the rate of electroosmosis and the zeta potential. We would expect that if we have changed the surface potential from negative to positive through the application of amines, that zeta potential would change sign and electroosmosis would go in the opposite direction. However, we do know from our old diffusion experiments that amino silane membranes can prevent positive molecules from diffusing through.
One way to explain both of these observations is that perhaps we are not getting as many positive groups on the inside of the pores as compared to the planar surface. Amino groups on the surface could prevent positive molecules from getting close enough, but in order to affect electrokinetics you must have the amino groups inside of the pores.