The Flory-Huggins theory was used to model the phase behaviour of linear low density polyethylene-citronellal binary mixtures. The model parameters were obtained from fitting the bimodal phase envelope using data points from cloud point determinations. This allowed the prediction of the melting point depression curve as well as the location of the spinodal region. A microporous polyethylene matrix was obtained by quenching homogeneous liquid mixtures at temperatures well below the spinodal phase boundary. This strategy makes it possible to trap, and effectively solidify, large amounts of citronellal in a polyethylene (LLDPE) matrix. This has potential implications for the development of long-lasting insect repellent bracelets and anklets.