The BET and BJH results of MIP showed a higher surface area and pore volume compared to the non-imprinted polymer (NIP). Can we say that the difference in morphology is because of the cavities present in the MIP? Or it is necessary for both the MIP and NIP to show similar morphology?
Dear Sonia, as you might know, the size of the cavities existing in the structure of MIP depends on the template molecule being used as the precursor. Since most of the molecules are significantly larger than the nitrogen molecules, the resulting cavities will be big enough for the nitrogen molecules to penetrate in and get adsorbed. Alternatively, since such cavities do not exist in NIP, we should expect to observe larger specific surface area for MIP in comparison with NIP. Not to mention, this justification is valid just in case the NIP and MIP particles are totally identical in terms of particle size, morphology, and internal struture and the only the difference is the existence of the template induced cavities. Otherwise, this rationale is not applicable at all.
Confirming what Mr. Ghamsari said, I should add that in most cases the presence of template in the porogenic solvent changes the chemicophysical properties of the polymerization reaction medium and results in relatively smaller particles. The smaller the particle size the higher the BET surface area. So, I would say that BET analysis is not sufficient to prove the imprinting effect. Beside the BET, you need to check the particles size (MIP and NIP) with SEM or DLS analysis. If the sizes are not the same you cannot say that the difference in the area is because of the cavities present in the MIP. To show the imprinting effect, you should calculate the imprinting factor (IF) and the selectivity.
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