Question

Currently working on a project where we want to functionalize PP membranes with various monomers. Our chemistries are aqueous and have therefore not been compatible with the membranes. The work-around we've been using is to utilize methanol to wet-out the PP.

I'm curious as to why this works. There isn't too much of a difference between water and methanol. Both are low molecular weight, both are polar and protic, both are capable of hydrogen bonding. What explanation is there for methanol readily absorbing into the membranes when water cannot?

Answer 1

Methanol can wet-out PP membranes due to its organic nature, lower polarity compared to water, and lower surface tension, making it more compatible with the hydrophobic membrane.

Step-by-step explanation:

The ability of methanol to wet-out polypropylene (PP) membranes as opposed to water can be attributed to its organic nature and lower surface tension compared to water.

Despite both liquids being polar and capable of forming hydrogen bonds, methanol has a methyl group, which is less polar and more compatible with the hydrophobic nature of PP.

Moreover, methanol's lower surface tension allows it to more easily penetrate the nonpolar regions of the membrane. As methanol molecules intercalate into the PP structure, they act as a carrier for the otherwise incompatible aqueous solutions.