TEMPO-oxidized cellulose nanofiber films: effect of surface morphology on water resistance

Abstract

2,2,6,6-Tetramethylpiperidine-1-oxyl radical (TEMPO)-oxidized cellulose nanofibers were prepared from two kraft pulps (Norway spruce and mixed eucalyptus) using the TEMPO/NaBr/NaClO system at pH 10 and 22°C. After reaction and mechanical treatment, the TEMPO-oxidized celluloses were used for preparation of self-standing films and coatings of laminate films on 50-lm-thick polyethylene terephthalate films. Characterization of the films was performed based on water contact angle measurements, laser profilometry, scanning electron microscopy, and field-emission scanning electron microscopy. The purpose of this study is to understand how the measured contact angles are affected by the film's physical properties (morphology, thickness, density, and roughness).

Nanofibrillated Cellulose from Appalachian Hardwoods Logging Residues as Template for Antimicrobial Copper

“…Saito et al (2009) [44] also reported that TEMPO/NaClO/NaClO 2 system provides CNF with up to approximately 1.5 times higher tensile strength (312 MPa) compared to those CNF from TEMPO/ NaBr/NaClO, which was again attributed to the higher DP of the final CNF. Moreover, Rodionova et al (2012) [8] reported that the final refining and homogenization process results in significantly higher defects and shorter lengths for hardwood nanofibers compared to softwood nanofibers; so, the correspondent tensile strengths of the softwood nanofiber films were significantly higher than the strengths of the hardwood nanofiber films.…”

“…In aqueous environments, TEMPO catalyzes the conversion of carbohydrate primary alcohols to carboxylate (COO-) functional groups in the presence of a primary oxidizing agent, for example, sodium hypochlorite (NaOCl). In particular, wood fibers can be 2 Journal of Nanomaterials converted to individual nanofibers 3-4 nm wide with several microns length by TEMPO-mediated oxidation and successive mild disintegration in water [7,8]. During this reaction significant amounts of C6 carboxylate groups are selectively formed on each cellulose microfibril surface with minimum changes of the original crystallinity of the cellulosic material.…”

Properties of hydroxypropyl guar/TEMPO-oxidized cellulose nanofibrils composite films

“…A rigid hydrogenbond network of cellulose nanofibrils governed by percolation might also form in the composite films (Zhou et al 2012). Figure 5 shows the contact angle (CA) change of a water droplet on the films with the increase of (Rodionova et al 2012a). The initial water contact angle of pure TOCNs film was 46.2°, consistent with the high hydrophilicity of the TOCNs film reported elsewhere (Fukuzumi et al 2009).…”

“…Cellulose nanofibrils (CNs) have attracted considerable attention in recent years due to their biodegradability, large surface area, high strength and high filmforming capacity (Rodionova et al 2012a). It is a highly reproducible and environmentally friendly nanomaterial (Fujisawa et al 2011) and has been used as the nano-fillers (Iwatake et al 2008), thin coating layers (Aulin and Strom 2013), and films (Song et al 2014) for many generic and cutting-edge products.…”

Self-assembled optically transparent cellulose nanofibril films: effect of nanofibril morphology and drying procedure

“…Casting is a time-consuming process, typically taking days or weeks. For example, Sehaqui et al (2010) reported that preparing 40-lmthick films with a diameter of 80 mm under atmospheric conditions starting with CNF concentration of 0.2 wt% took more than 120 h. To accelerate the processing, the castings are sometimes carried out with slight heating under vacuum (Spence et al 2010;Xhanari et al 2011;Rodionova et al 2012). A second popular and relatively fast method to produce CNF films involves the filtration of CNF solutions and drying the obtained hydrogels (Henriksson et al 2008;Qing et al 2013b).…”