Hello, I measured the zeta potential of PEGDA hydrogel microparticles which is a cube with a side length is 20 um. Particles are suspended on DI water + tween 20
Since particles are only composed of PEGDA, I expected the ~ zero zeta potential value, but the results were -40 mv with 0.0404 mS/cm conductivity.
Is it possible for nonionic PEG particles to have negative zeta potential value? or is it because of tween 20?
Please note that the pH of solution was ~7
Thanks in advance.
Yoonho Roh A quoted zeta potential (ZP) without an associated pH value is not very useful... Mobility of 20 micron particles is slow and, further, ZP is not very useful as a marker of stability for particles this size. Inertial effects will overcome any van der Waals attractive forces.
Yoonho Roh
I want to draw your attention to two oddities.
1.You have synthesized a hydrogel or shaped it into a cube. Hydrogels in solution form spherical coils.
2.PEGDA in aqueous solution must be partially hydrolyzed with the presence of a dissociated carboxyl group in the solution
If the pH is 7, this indicates that the proton is bound by non-covalent oxygen electron pairs in the PEG. When an electric field is applied, an excess of protons appears and forces the hydrogel to move to the negative electrode during electrophoresis. Therefore, the device displays a negative zeta potential.
Roughly at pH=9 the zeta potential could be zero for PEGDA. However, you should titrate the solution (measure the zeta potential at different pHs) to find the isoelectric point (a pH at which the zeta potential is zero).
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