Tailoring sustainable electrospun poly(vinyl alcohol)/carboxymethyl cellulose (PVA/CMC) nanofibrous films: Enhanced mechanical, thermal, and barrier properties via methanol stabilization for multifunctional applications.

Electrospun poly(vinyl alcohol) (PVA)-based nanofibrous membranes are promising sustainable alternatives to conventional plastics; however, achieving simultaneous control over mechanical integrity, moisture sensitivity, and optical shielding remains challenging. In this study, PVA/carboxymethyl cellulose (CMC) nanofibrous membranes with varying blend ratios (PVA:CMC = 10:0, 9:1, 8:2, and 7:3) were fabricated by electrospinning and stabilized via methanol post-treatment to tune structure and performance. Morphology, intermolecular interactions, thermal behavior, mechanical properties, water interactions, barrier performance, and optical transmittance were evaluated. CMC incorporation refined fibre morphology by reducing fibre diameter and enhancing UV-shielding ability, while improving thermal stability through stronger PVA-CMC intermolecular interactions. In untreated membranes, increasing CMC content decreased solubility and moderated swelling through formation of a denser interpolymer network; however, water vapor permeability increased from 5.28 ± 0.16 × 10-10 g·m/(m2·Pa·s) for neat PVA to 13.6 ± 0.41 × 10-10 g·m/(m2·Pa·s) for the 7:3 blend. Methanol post-treatment effectively addressed this limitation by inducing hydrogen-bond reorganization and network densification, resulting in enhanced mechanical integrity, thermal resistance, and reduced solubility across all compositions. Although methanol treatment caused a modest increase in swelling due to solvent-induced chain rearrangement, it substantially improved moisture-barrier performance, reducing WVP by approximately 40-90%, reaching as low as 1.35 ± 0.1 × 10-10 g·m/(m2·Pa·s). Among all formulations, the PVA/CMC (8:2) membrane exhibited the most balanced multifunctional performance. These findings demonstrate that CMC incorporation and methanol post-treatment act as complementary design tools, enabling a scalable, crosslinker-free strategy to engineer biodegradable nanofibrous membranes with tunable mechanical, thermal, barrier, and optical properties.