Junya Wang, Peisen Gao, An Zhang, Sheng Chen, Feng Xu
Lignocellulosic nanofibrils (LCNFs) are promising bio-based nanofillers for constructing multifunctional polymer composite films, yet their efficient production from raw lignocellulosic biomass remains challenging. Herein, microwave-assisted deep eutectic solvent pretreatment (MW-DES) coupled with high-pressure homogenization (HPH) was used to produce LCNFs from giant reed (Arundo donax L.). An acidic benzyltrimethylammonium chloride/oxalic acid dihydrate (BTMAC/OAD) DES enabled rapid fractionation within 10-20 min by selectively removing hemicellulose and part of the lignin, yielding cellulose-rich solid residues (SRs) that were readily nanofibrillated. The obtained LCNFs exhibited high aspect ratios, with diameters mainly in the 2-12 nm range (all below 20 nm) and lengths typically ranging from approximately 300 to 600 nm. FTIR analysis supported the retention of residual lignin, whereas XRD confirmed the preservation of the cellulose I allomorph and an increase in apparent crystallinity relative to the raw material (RM). When incorporated into polyvinyl alcohol (PVA), the LCNFs imparted pronounced UV attenuation across 200-400 nm and tunable haze while maintaining high visible-light transparency and substantially improving mechanical strength. The best-performing film reached a tensile strength of 72.9 MPa, approximately 143% higher than neat PVA. This work demonstrates a rapid route to LCNFs and highlights their potential as multifunctional reinforcements for transparent, light-managing polymer composite films.