Deep eutectic solvent as plasticizing agent for the zein based films

This study explores, the impacts of incorporating of deep eutectic solvent (DES) as plasticizer on the characteristics of zein films. Investigation focused on examining the mechanical, thermal, surface, and microstructural properties of zein films that were plasticized using DES. The findings of the study revealed that by adding DES to zein films, there was an observed improvement in transparency. Additionally, it was observed that up to a 20% addition of DES led to a reduction in water vapor permeability (WVP). However, beyond this level, the WVP increased as the surface hydrophobicity decreased. The films that were plasticized with DES showed higher tensile and burst strength values than control. However, there was a decrease in the elongation at break and burst distance, except for the film containing 30% DES. The addition of DES as plasticizer resulted in smoother surface morphology compared to the control, and all films revealed homogeneous and non-porous surface and cross-section microstructure. The films plasticized with DES displayed three different thermal degradation temperatures resulting in higher thermal stability. The FT-IR spectrum of films showed similar backbone structure including Amide I, II and III bands. However, 5% DES plasticized film showed different secondary structural peaks of Amide I band due to lower α-helix and higher β-sheet and random coil content. The findings of this investigation indicate that the employment of DES as plasticizer in biodegradable polymer films can yield enhanced mechanical and barrier characteristics compared to conventional plasticizers, thus demonstrating its potential for effective use.