title: Characterisation and properties of homo- and heterogenously phosphorylated nanocellulose.
abstract: Nano-sized cellulose ester derivatives having phosphoryl side groups were synthesised by phosphorylation of nanofibrilated cellulose (NFC) and nanocrystaline cellulose (NCC), using different heterogeneous (in water) and homogeneous (in molten urea) processes with phosphoric acid as phosphoryl donor. The phosphorylation mechanism, efficacy, stability, as well as its influence on the NC crystallinity and thermal properties, were evaluated using ATR-FTIR and (13)C NMR spectroscopies, potentiometric titration, capillary electrophoresis, X-ray diffraction, colorimetry, thermogravimmetry and SEM. Phosphorylation under both processes created dibasic phosphate and monobasic tautomeric phosphite groups at C6 and C3 positioned hydroxyls of cellulose, yielded 60-fold (∼1,173 mmol/kg) and 2-fold (∼1.038 mmol/kg) higher surface charge density for p-NFC and p-NCC, respectively, under homogenous conditions. None of the phosphorylations affected neither the NC crystallinity degree nor the structure, and noticeably preventing the derivatives from weight loss during the pyrolysis process. The p-NC showed high hydrolytic stability to water at all pH mediums. Reusing of the treatment bath was examined after the heterogeneous process.
authors: University of Maribor, Faculty of Mechanical Engineering, Institute for Engineering Materials and Design, Maribor, Slovenia. Electronic address: vanja.kokol@um.si.
authors: Vanja
authors: V
authors: Kokol
authors: University of Maribor, Faculty of Mechanical Engineering, Institute for Engineering Materials and Design, Maribor, Slovenia.
authors: Mojca
authors: M
authors: Božič
authors: University of Maribor, Faculty of Mechanical Engineering, Institute for Engineering Materials and Design, Maribor, Slovenia.
authors: Robert
authors: R
authors: Vogrinčič
authors: Luleå University of Technology, Department of Civil, Environment and Natural Resources Engineering, Division of Process Engineering, Luleå, Sweden.
authors: Aji P
authors: AP
authors: Mathew
mesh_terms: D002482:Cellulose / Q000737:chemistry*; D006358:Hot Temperature; D006863:Hydrogen-Ion Concentration; D006868:Hydrolysis; D053758:Nanoparticles / Q000737:chemistry*; D010756:Phosphoric Acids / Q000737:chemistry*; D010766:Phosphorylation
chemical_list: D010756:Phosphoric Acids; D002482:Cellulose; C030242:phosphoric acid
keywords: Heterogeneously; Homogeneously; Hydrolytic stability; Nanocellulose; Phosphorylation; Treated solution re-usage