Quaternised cellulosic materials prepared from chain-growth polymerisation of a grafted reactive ionic liquid

Grafting-onto modified cellulosic materials using reactive ionic liquids (RILs) is emerging as a green and versatile strategy to tailor surface chemistry and functionality. This paper investigates the process–structure–property relationships of quaternised celluloses using glycidyltriethylammonium chloride (GTEAC) as a RIL, and microfibrillated cellulose (MFC) and nanocrystalline cellulose (NCC) as core materials. The resulting quaternised materials, QMFC and QNCC, exhibited distinct chemical and structural changes confirmed by FTIR, SEM/EDX, and WAXS/SAXS. The chain-growth polymerisation of GTEAC on MFC or NCC led to a substantial reduction in crystallinity, or an increase in the amorphous content (QMFC: from 85% to 54%; QNCC: from 82% to 60%), while the crystalline domains remain intact. Moreover, grafting increased the intercrystallite spacing (QMFC: from 4.3 to 5.8 nm; QNCC: from 3.7 to 5.0 nm), indicating that the poly-GTEAC chains intercalate in the amorphous domains and between crystallites. Thermal analyses (TGA/DSC) demonstrated that grafted materials start decomposing at lower temperatures (QMFC: from 283 °C to 133 °C; QNCC: from 281 °C to 142 °C). Dynamic vapour sorption (DVS) studies showed that equilibrium moisture uptake at aw = 0.95, as well as the monolayer capacity and the specific surface area values, nearly doubled. Notably, QNCC exhibited superior grafting efficiency and sorptive performance due to its high surface-to-volume ratio.