Enhancing Mechanical Flexibility and Water-Barrier Properties of Ethyl Cellulose Gels Using Hydroxylated Linseed Oil as a Sustainable Plasticizer

The growing demand for sustainable, natural-based polymeric materials has accelerated research into cellulose-derived gels. Ethyl cellulose (EC) is a promising candidate; however, its high brittleness, limited flexibility, and insufficient water barrier properties often require the use of a plasticizer to improve its performance. In this study, we synthesized hydroxylated linseed oil polyol (LPO) and evaluated its performance as a bio-based plasticizer for EC-derived dried gels. LPO was characterized by 1H NMR, 13C NMR and FTIR. In addition, quantitative tests further confirmed high hydroxyl value of 280.36 ± 28.96 mg KOH/g. Incorporating LPO into the EC organogel matrix improved the functional performance of dried gel composites, including their mechanical, water vapor barrier, thermal, and morphological properties. The greatest plasticizing performance was achieved at the highest concentration investigated (30% w/w), with a fivefold increase in elongation at break compared to the pristine EC, together with the lowest WVP value (~13 g·mm·m−2·kPa−1·day−1), while maintaining good thermal stability and a smooth, homogeneous surface morphology. In addition, FTIR, SEM, and accelerated aging analyses supported the good compatibility and stability of the EC/LPO system. These effects are attributed to intermolecular interactions between EC chains and LPO. Overall, LPO is demonstrated to be an effective bio-based plasticizer for advancing sustainable bioplastic materials, highlighting its potential to replace conventional plasticizers.