Specific water uptake of thin films from nanofibrillar cellulose

Kontturi, Katri S.; Kontturi, Eero; Laine, Janne

doi:10.1039/c3ta12998e

Cited by 53 publications

(79 citation statements)

References 84 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Figure 2e displays the same features however, the SPR peak has shifted to higher angles due to the presence of CNCs at the sensor surface. 29 In addition, the breadth of the SPR peak increases following CNC deposition indicating that the roughness at the air interfaces has increased, correlating with AFM roughness measurements. 34 Figure 2f presents the n-d continuum from which d and n of the film were determined.…”

Section: Cnc Films In Airmentioning

confidence: 61%

“…Plotting the two continua on the same axis determined the intersection point and solutions for n and d. Assuming CNC films behave as Cauchy materials, when used, the chromatic dispersion relation (dn/dλ) of pure cellulose was taken to be 0.0271 µm -1 and used to shift the 670 nm continuum. 29,51 Notably dn/dλ for air was considered negligible. Both shifted and non-shifted continua displayed intersection points and the difference between the two is taken as the uncertainty in the fitting and is discussed below.…”

Section: Surface Plasmon Resonancementioning

confidence: 99%

“…29 Importantly, the authors note that sample heterogeneity within the cellulose nanofibril film made SPR measurements and data fitting very challenging. Here we test smooth and uniform CNC films in a variety of suitable SPR solvents: water, acetone, methanol, acetonitrile, isopropanol, and ethanol, and although they do not represent common hydrophobic polymers in terms of their solubility parameters (i.e., polyethylene or polystyrene), they do mimic polymers aimed towards biodegradable composites and biomedical applications such as poly(vinyl alcohol), poly(lactic acid) and poly(vinyl pyrrolidone).…”

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Cellulose nanocrystal interactions probed by thin film swelling to predict dispersibility

2016

View full text Add to dashboard Cite

The production of well-dispersed reinforced polymer nanocomposites has been limited due to poor understanding of the interactions between components. Measuring the cohesive particle-particle interactions and the adhesive particlepolymer interactions is challenging due to nanoscale dimensions and poor colloidal stability of nanoparticles in many solvents. We demonstrate a new cohesive interaction measurement method using cellulose nanocrystals (CNCs) as a model system; CNCs have recently gained attention in the composites community due to their mechanical strength and renewable nature. Multi-wavelength surface plasmon resonance spectroscopy (SPR) was used to monitor the swelling of CNC thin films to elucidate the primary forces between CNCs. This was achieved by measuring swelling in situ in water, acetone, methanol, acetonitrile, isopropanol, and ethanol and relating the degree of swelling to solvent properties. Films swelled the most in water where we estimate 1.2-1.6 nm spacings between CNCs (or 4-6 molecular layers of water).Furthermore, a correlation was found between film swelling and the solvent's Hildebrand solubility parameter (R 2 =0.9068). The hydrogen bonding component of the solubility parameters was more closely linked to swelling than the polar or dispersive components. The films remained intact in all solvents, and using DLVO theory we have identified van der Waals forces as the main cohesive interaction between CNCs. The trends observed suggest that solvents (and polymers) alone are not sufficient to overcome CNC-CNC cohesion and that external energy is required to break CNC agglomerates. This work not only demonstrates that SPR can be used as a tool to measure cohesive particle-particle interactions but additionally advances our fundamental understanding of CNC interactions which is necessary for the design of cellulose nanocomposites.

show abstract

Section: Cnc Films In Airmentioning

confidence: 61%

Section: Surface Plasmon Resonancementioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Cellulose nanocrystal interactions probed by thin film swelling to predict dispersibility

2016

View full text Add to dashboard Cite

show abstract

“…In recent years, cellulose thin films have attracted significant interest in both basic and applied research since they provide a confined two dimensional environment with defined morphology and chemistry (Kontturi et al 2003(Kontturi et al , 2006(Kontturi et al , 2013. Therefore, they have been proposed as supports for biosensors, as matrix for catalysis as well as material for optoelectronic devices such as transistors and solar cells (Blomstedt et al 2007;Filpponen et al 2012;Niegelhell et al 2016;Orelma et al 2011Orelma et al , 2012Reishofer et al 2017;Taajamaa et al 2013;Wolfberger et al 2015).…”

Section: Introductionmentioning

confidence: 99%

Homogeneous cellulose thin films by regeneration of cellulose xanthate: properties and characterization

et al. 2017

View full text Add to dashboard Cite

The preparation and characterization of cellulose thin films derived from cellulose xanthate is reported. The films are prepared by depositing alkaline aqueous solutions of cellulose xanthate onto silicon wafers, followed by a spin coating step. Depending on the xanthate concentration used for spin coating, films with 50 and 700 nm thickness are obtained. The cellulose xanthate is converted to cellulose by exposing the films to HCl vapors over a period of 20 min. The conversion is monitored by ATR-IR spectroscopy, which allows for tracking the rupture of C-S and C=S bonds during the regeneration process. The conversion is accompanied by a reduction of the film thickness of ca 40% due to the removal of the bulky xanthate group. The films feature a homogenous, but porous morphology as shown by atomic force microscopy. Further, the films were investigated towards their interaction with Bovine Serum Albumin (BSA) and fibrinogen by means of multi-parameter surface plasmon resonance spectroscopy. Similar as other cellulose thin films BSA adsorption is low while fibrinogen adsorbs to some extent at physiological pH (7.4).

show abstract

“…This is surprising because both the cellulose surface and APAMs possess anionic charge and therefore should repel each other. However, the NFC model surface is porous (Kontturi et al 2013), indicating that some polymer can be entrapped or can disperse nanocellulose fibrils (increase the swelling), an effect that contributes to Δf. In any case, the APAMs were seemingly poorly attached to the surface.…”

Section: Adsorption Experimentsmentioning

confidence: 99%

Deflocculation of Cellulosic Suspensions with Anionic High Molecular Weight Polyelectrolytes

Korhonen¹,

Sorvari²,

Saarinen³

et al. 2014

BioResources

Self Cite

View full text Add to dashboard Cite

Pulp fibers have a strong tendency to form flocs in water suspensions, which may cause their undesirable distribution in the paper sheets. This flocculation can be controlled by adding, e.g., an anionic high molecular weight polyelectrolyte in the fiber suspension. The objective of this study was to investigate the effect of anionic polyelectrolytes on deflocculation kinetics, dewatering, and rheology of cellulosic suspensions. The results showed that both microfibrillated cellulose (MFC) and macroscopic pulp fibers can be dispersed using anionic polyacrylamides (APAM). The higher the molecular weight of APAM, the higher is its effect. Adsorption experiments illustrate that anionic polyelectrolytes do not strongly attach to cellulose surfaces but they can be partly entrapped or can disperse nanocellulose fibrils (increase the swelling). Based on rheological experiments, the MFC network became weaker with APAM addition. Similar to the flocculation mechanism of cellulosic materials with polymers, deflocculation is also time dependent. Deflocculation occurs very rapidly, and the maximum deflocculation level is achieved within a few seconds. When mixing is continued, the floc size starts to increase again. Also dewatering was found to be strongly dependent on the contact time with the APAMs. These results indicate that the positive effects of anionic deflocculants are quickly diminished due to shear forces, and therefore, the best deflocculating effect is achieved using as short a contact time as possible.

show abstract

Specific water uptake of thin films from nanofibrillar cellulose

Cited by 53 publications

References 84 publications

Cellulose nanocrystal interactions probed by thin film swelling to predict dispersibility

Cellulose nanocrystal interactions probed by thin film swelling to predict dispersibility

Homogeneous cellulose thin films by regeneration of cellulose xanthate: properties and characterization

Deflocculation of Cellulosic Suspensions with Anionic High Molecular Weight Polyelectrolytes

Contact Info

Product

Resources

About