Hydrophobic deep eutectic solvents as plasticizers in low-density polyethylene films

Abstract

In this study, the performance of hydrophobic deep eutectic solvents (HbDESs) as plasticizers for low-density polyethylene (LDPE) films was investigated, and the results were compared with those of di(2-ethylhexyl) phthalate (DEHP) plasticizers. DESs were produced by mixing choline chloride (ChCl) (hydrogen bond acceptor, HBA) with hexanoic acid (HA) and pentanoic acid (PA) as hydrogen bond donors (HBDs) at 1:1 and 1:2 molar ratios. The prepared DESs were added to LDPE at two different ratios based on polymer weight (10% and 30%), and twin-screw extruder was used for film production. The densities of the plasticizers were determined to be 1 g/cm³ and below, viscosities ranging from 11 to 203 mPa·s, the pH was above 1 and the volatility exceeded 0.9%. FTIR and DSC analyses indicated that bonding interactions between HBA and HBD were established, confirming the successful production of DESs. After adding the plasticizers to the LDPE films at specific rates, the films were characterized based on mechanical, barrier, optical, thermal, molecular bond, microstructural, water behavior properties, and overall migration (OM) analyses. Among the films, the first three with the best properties (CH1:30, CP1:30, and DEHP:30) were identified using the multicriteria decision hierarchy technique (TOPSIS). When comparing the films with DESs to the control group and those with DEHP, significantly better results were achieved in terms of the elongation, barrier performance, light transmittance, and OM values. These findings demonstrate the potential of HbDESs as effective plasticizers in LDPE films.