Detailed explanation of the difference between cellulose nanofibers and cellulose nanocrystals

With the development of renewable resource technology, cellulose nanomaterials are attracting widespread attention from scientific research and industry because of their green, environmentally friendly, high-performance, biodegradable properties. Among them, cellulose nanofibers ( CNF, Cellulose Nanofibers ) and cellulose nanocrystals ( CNC, Cellulose Nanocrystals ) are the two main forms. Although they are homologous from natural cellulose, there are essential differences in structural characteristics, preparation process, physical properties and applicable fields . This article will make detailed distinctions between the two from multiple perspectives to help readers better understand and apply these two types of materials.

1. The essential differences in structural forms

Cellulose is composed of alternating crystal regions and amorphous regions. The biggest difference between CNC and CNF is that the two retain and remove these two regions is different.

property	Cellulose nanofibers ( CNF)	Cellulose nanocrystals ( CNC)
source	Wood pulp, cotton pulp, plant straw, etc.	Same as above
form	Flexible filamentous, mesh structure	Rigid rod-shaped, regular crystal
size	Diameter 5–50 nm, length 1–10 μm	Diameter 5–20 nm, length 100–500 nm
composition	Contains crystal region and amorphous region	Mainly high crystalline area
Specific surface area	高	Higher
Surface characteristics	Adjustable and easy to function	Negatively charged, easy to disperse

In short, CNF is more like a fine ' nanonet ' , while CNC is like a highly regular ' nanorod '。

2. The core differences in preparation methods

Preparation of CNF : Mainly mechanical treatment, such as high-pressure homogenization, ultrafine grinding or microfluidic treatment, is often supplemented by chemical pretreatment such as enzymatic lysis or TEMPO oxidation, to reduce the strength of hydrogen bonds between fibers and promote fiber dispersion.

Preparation of CNC : The amorphous region is selectively dissolved by hydrolysis of concentrated sulfuric acid, and only the crystalline part is retained, thus forming a relatively rigid nanocrystal.

Therefore, CNF is a flexible nanonetwork obtained by ' separation ' method, while CNC is a hard nanocrystal obtained by ' shear ' method.

3. Comparison of performance characteristics

Performance metrics	CNF	CNC
Mechanical properties	High flexibility, high tensile strength	High rigidity, high modulus
Suspension stability	Slightly worse, easy to tangle and flocculate	Excellent, small particle size, good dispersion
Film-forming capability	Excellent film forming properties, suitable for coating	Poor film forming properties, mostly used for reinforcement fillers
Optical transparency	Depend on concentration and arrangement	Have certain optical anisotropy
Biocompatibility	good	good
Surface modification	Various ways of esterification, etherification, graft polymerization, etc.	Sulfate, negative charge dispersion stable

4. Differentiation of application directions

Although both are widely used in polymer materials, biomedicine, food, electronics and other fields, their focus is also different due to their different forms and physical properties:

Application areas	CNF (flexible type)	CNC (rigid type)
Packaging materials	Bio-based films, coated paper, food contact materials	Film reinforcer, transparent barrier layer
Biomedical	Gel dressings, sustained release carriers, tissue engineering scaffolds	Drug carriers, diagnostic microspheres
Composite materials	Plastic reinforcement, rubber modification, building filler	Thermoset resin reinforced, optical composite material
cosmetic	Thickener, moisturizing gel, emulsifying stabilizer	Dispersants, rheology regulators
Flexible Electronics	Flexible conductor substrate, printed electronic paper	Optical enhancer, dielectric support

5. Choosing suggestions and future development

In specific applications, the appropriate type should be selected according to the needs of the terminal product:

If you pursue film formation, flexibility or structural enhancement , CNF is preferred；

If the size is consistent, the dispersion is good, and the rigidity is enhanced , CNC should be selected.。

In the future, with the upgrading of preparation technology and the improvement of cost control capabilities, the composite application of CNF and CNC will also become a trend, such as showing greater potential in high-end fields such as multi-layer film structures, smart materials, and green batteries.