University of Maribor, Faculty of Mechanical Engineering, Institute for Engineering Materials and Design, Maribor, Slovenia.
University of Maribor, Faculty of Mechanical Engineering, Institute for Engineering Materials and Design, Maribor, Slovenia.
Carbohydr Polym. 2015 Jul 10;125:301-13. doi: 10.1016/j.carbpol.2015.02.056. Epub 2015 Mar 12.
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.
具有磷酸侧基的纳米级纤维素酯衍生物是通过使用不同的异相（在水中）和均相（在熔融尿素中）过程，用磷酸作为磷酸供体，对纳米原纤化纤维素（NFC）和纳米纤维素晶体（NCC）进行磷酸化合成的。使用 ATR-FTIR 和（13）C NMR 光谱、电位滴定、毛细管电泳、X 射线衍射、比色法、热重法和 SEM 评估了磷酸化的机理、功效、稳定性，以及其对 NC 结晶度和热性能的影响。在这两种过程下，磷酸化在纤维素的 C6 和 C3 位的羟基上产生了磷酸二酯和磷酸单酯基团，在均相条件下，p-NFC 和 p-NCC 的表面电荷密度分别提高了 60 倍（约 1,173 mmol/kg）和 2 倍（约 1.038 mmol/kg）。这些磷酸化都没有影响 NC 的结晶度和结构，并且显著地防止了衍生物在热解过程中的失重。p-NC 在所有 pH 介质中对水具有高的水解稳定性。在异相过程之后，考察了处理浴的再利用。
