Trapping citronellal in a microporous polyethylene matrix

Abstract

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.

Mosquito‐repellent controlled‐release formulations for fighting infectious diseases

“…Microporous materials gained most interest in several potential membrane applications in the fields of microfiltration, ultrafiltration, reverse osmosis, gas separation, clean energy, catalysis and storage media due to their extraordinary high porosity and surface area [ 105 ]. Various solvents such as dioxane/water, chloroform, methanol, ethanol, hexane, or dichloromethane with polymers such as (i) polypropylene (PP) [ 102 , 106 – 108 ], polyvinylidene fluoride (PVDF) [ 109 – 112 ], (iii) poly(ethylene-co-vinyl alcohol) (EVOH) [ 113 , 114 ], (iv) polystyrene [ 115 , 116 ], (v) polyethylene (PE) [ 101 , 102 , 106 , 117 – 122 ], or poly (lactic acid) [ 123 ] have been used to form microporous structures through the TIPS method. Therefore, the preparation of microporous structures using polyolefins is widely explored due to their good thermal and solvent resistance as well as their low cost.…”

“…repellent). The liquid is mostly a low molecular weight and high-boiling-point diluent in which the polymer is actually insoluble at room temperature [ 117 ]; (ii) the solution is then rapidly cooled or quenched to induce solid-liquid or liquid-liquid (L-L) phase separation; (iii) the liquid is extracted from the polymer device by an appropriate solvent or by evaporation (at ambient temperature), and finally, (iii) a microporous polymer with the desired structure is formed.…”

Phase behavior of the polymer/drug system PLA/DEET: Effect of PLA molar mass on subambient liquid-liquid phase separation

“…The repellent can then be gradually delivered to the environment, with the evaporation rate expected to be adjustable by the crystallizationcontrolled scaffold morphology. A similar approach of forming a microporous polymer structure via TIPS for the system polyethylene/citronellal employed instead L-L demixing followed by crystallization [17].…”

Development, characterization and modeling of mosquito repellent release from microporous devices

“…It was important to estimate the degree of shrinkage of the polymer matrix strands containing repellents. According to Akhtar and Focke, [ 7 ] this dimensional instability is undesirable in products, such as insect repellent wearable devices. Swelling of the polymer strands implies the possibility of shrinkage when the repellent is released.…”

“…[ 6 ] One way is to force phase separation by spinodal decomposition to induce a co‐continuous phase structure with the liquid repellent trapped inside the pores defined by the polymer scaffold. [ 7 ] Such open‐cell foam phase structures are relatively easy to obtain by extruding hot homogeneous polymer‐repellent melts into an ice‐cold water bath. In the case of LLDPE as scaffold, the solubility of the polar repellent in the nonpolar semi‐crystalline polymer is very low.…”