Pretreatment-dependent surface chemistry of wood nanocellulose for pH-sensitive hydrogels.
Bottom Line: The pre-treatments yielded a highly nanofibrillated material, with significant amounts of aldehyde and carboxyl groups.This is due to the swelling capacity of the 3D micro-porous structures, which have ionisable functional groups.In this study, we demonstrated that nanocellulose gels have a significantly higher swelling degree in neutral and alkaline conditions, compared to an acid environment (pH 3).
Affiliation: Paper and Fibre Research Institute (PFI) - Høgskoleringen 6b, Trondheim, Norway email@example.com.Show MeSH
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Mentions: Assessment of the surface microstructure was complemented with a detailed assessment of the surface nano-structure with AFM (Figure 2). Note that the CMNC-sample has a major fraction of cellulose nanofibrils with average width 15 nm (±0.8 nm). Interestingly, the CMPNC-sample seems to be composed of relatively thicker and apparently shorter nanofibrils (Figure 2(b)). The average width of the CMPNC sample is 20 nm (±0.8 nm) as quantified automatically by image analysis of the AFM images. The nanofibril width distribution of the CMNC and CMPNC samples is given in Figure 3. Care must be taken when quantifying the width distribution of nanofibrils with AFM as the lateral dimensions may be overestimated depending on the used AFM tip. In this study, the thicker morphology of the nanofibrils is in accordance with the quantification performed by Liimatainen et al.,12 who reported nanofibril widths of approximately 25 nm (±6 nm). Note that individualized nanofibrils yielded by e.g. TEMPO-mediated oxidation or carboxymethylation have been reported to have widths of less than 20 nm.2,11,31–33Figure 2.
Affiliation: Paper and Fibre Research Institute (PFI) - Høgskoleringen 6b, Trondheim, Norway firstname.lastname@example.org.