Molecular interactions of polymer oleogelation

Abstract

We have successfully gelled ethyl cellulose (EC) in different vegetable oils. This work investigated the molecular interactions responsible for such gelation process. Rheological measurements show that flaxseed oil gels need a larger yield force than soybean and canola analogues. We have used both Raman and IR spectroscopy to elucidate which functional groups are involved in the gelation process. We have found that the glycerol group of the triglycerides behaves in the same way in the free oil as in the gel. This is an indication that the specificity seen by using different oils is not due to electrostatic interactions involving this functional group. Our results show that the conformation of the lipid chains is mainly responsible for solvent–solvent interaction. However, the difference seen in the rheological properties is explained in terms of polymer–solvent interactions. These are influenced by the molar volume of the solvent, which is dependent on the amount of unsaturations, such that the larger volume leads to an increased separation of the polymer strands and a decrease in the number of tie points in the polymer network.