Preparation of Cellulose Nanofibrils by Multi-Site Regioselective Oxidation

Nanocellulose by Ammonium Persulfate Oxidation: An Alternative to TEMPO-Mediated Oxidation

“…The development of carboxylic acid content approaches an asymptotic limit at approximately 1.5 mmol/g after 10 h of oxidation. This is close to the theoretical maximum of 1.71 mmol/g using the 110 and (110) plane dimensions reported by Nishiyama for the unit cell and the average length and diameter for the nanofibers produced in this investigation. − …”

Fluorescent labeling and characterization of dicarboxylic cellulose nanocrystals prepared by sequential periodate–chlorite oxidation

“…The FTIR spectrum of CNC has evident cellulose spectral characteristics: 3419 cm −1 , 2903 cm −1 , and 1747 cm −1 correspond to the tensile vibration of –OH in cellulose, CH, and C O on the carboxyl group, respectively. 42 In the FTIR spectrum of FCNC, the spectral characteristics of CNC are clearly observed, and two new peaks appeared at 1623 cm −1 and 1534 cm −1 . The peak at 1623 cm −1 corresponds to the C C tensile vibration of the aromatic ring of AMC on the FCNC surface, and 1534 cm −1 corresponds to the N–H bending vibration and C–N tensile vibration of the newly formed amide group.…”

“…Assuming that the dicarboxylic CNC is a rectangular parallelepiped model with a length of 105.3 nm and a width of 9.4 nm (square section), the microstructure model previously studied was applied. 42 Thus, the values considered were: length of cellobiose of 1.03 nm, lateral interval between cellulose molecular chains of 0.53 nm, and longitudinal interval of 0.61 nm. 42 The number of cellulose molecular chains on the CNC cross section was (9.4/0.53 + 1) × (9.4/0.61 + 1) = 307.…”

“… 42 Thus, the values considered were: length of cellobiose of 1.03 nm, lateral interval between cellulose molecular chains of 0.53 nm, and longitudinal interval of 0.61 nm. 42 The number of cellulose molecular chains on the CNC cross section was (9.4/0.53 + 1) × (9.4/0.61 + 1) = 307. The number of AGUs per cellulose chain was 105.3/0.515 = 204, and the total number of AGUs contained in a single CNC particle was 62 864.…”

Regioselectively Carboxylated Cellulose Nanofibril Models from Dissolving Pulp: C6 via TEMPO Oxidation and C2,C3 via Periodate–Chlorite Oxidation

“…With blending, CNFs in 10–20 nm widths have been reported in yields up to 50% [ 15 ] while thinner 2.6–6 nm wide CNFs could be produced in higher 84–100% yields but with an excess of both PC oxidants and aided by microfluidization [ 16 ] or high-pressure homogenization [ 18 ]. Applications of both TEMPO and periodate oxidations have only been reported on microcrystalline cellulose [ 19 ]. Since microcrystalline cellulose is already hydrolyzed (commonly by hydrochloric acid) and mechanically refined from pulp or other sources of cellulose, these oxidations are expected to affect the surfaces of 15–30 μm sized microcrystalline cellulose particles; therefore, they do not provide insight into how these oxidants access and react with the C6 vs. C2 and C3 hydroxl groups in native or chemically unmodified cellulose.…”