In-depth comparison: The difference between carboxylated modified nanocellulose and traditional nanocellulose

The difference between carboxylated modified nanocellulose and nanocellulose is not only reflected in chemical composition and structure, but also in their physical properties, functional properties, stability and application fields. The difference between the two will be explained in detail through a more in-depth comparison.

1. Differences in chemical structure and functional groups

Nanocellulose:

Chemical structure: Nanocellulose is a nanoscale fiber material extracted from natural cellulose. Cellulose is a polymer compound formed by glucose units connected through β-1,4 glycosidic bonds. The crystal structure of natural cellulose is relatively tight. Nanocellulose degrades cellulose into nano-scale fibers through chemical or mechanical treatment, with high specific surface area and good mechanical properties.

Surface functional groups: The surface of unmodified nanocellulose contains a large number of hydroxyl (–OH) functional groups, which make them highly hydrophilic. However, since the surface is mainly composed of hydroxyl groups, unmodified nanocellulose has a weak surface charge, which is not enough to prevent its aggregation and precipitation in water.

Carboxylated modified nanocellulose:

Chemical structure: Carboxylated modified nanocellulose is surface chemically modified by introducing polar functional groups such as carboxyl groups (–COOH) based on the original nanocellulose. Oxidation reactions (such as sodium chlorate, hydrogen peroxide) or grafting chemical reactions (such as chloroacetic acid or acrylic acid, etc.) are usually used to introduce carboxyl groups to the surface of the nanocellulose. These carboxyl groups are covalently linked to the hydroxyl groups on the cellulose chain.

Surface functional groups: In addition to the original hydroxyl group (–OH), a large number of carboxylated (–COOH) functional groups are introduced on the surface of carboxylated modified nanocellulose. These carboxyl groups make the modified nanocellulose surface negatively charged, greatly enhancing its hydrophilicity and having stronger dispersion.

2. Differences in water solubility and dispersion

Nanocellulose:

Hydrophilicity: The surface of unmodified nanocellulose only contains hydroxide groups, which has strong hydrophilicity, but its water solubility is poor, especially in high concentrations or high salt environments, which are prone to agglomeration. Although nanocellulose can absorb water and interact with water, its dispersion is not stable in water due to the limitations of surface functional groups.

Dispersibility: The dispersibility of nanocellulose in aqueous solutions is poor, especially in high concentration systems, which easily forms agglomeration, thereby affecting its application effect.

Carboxylated modified nanocellulose:

Hydrophilicity: Due to the introduction of carboxyl groups, the hydrophilicity of modified nanocellulose is significantly enhanced. The carboxyl group not only improves its ability to disperse in water, but also improves its solubility in polar solvents. Through carboxylation modification, the dispersion of nanocellulose in aqueous solution is significantly better than that of unmodified nanocellulose.

Dispersibility: The nanocellulose introduced by carboxyl groups has a strong negative surface charge, which makes it exhibit good dispersibility in water, especially in high concentrations or high electrolyte solutions. Negative charge can effectively prevent mutual attraction between particles, reduce agglomeration, and maintain the stability of the solution.

3. Differences in surface charge and stability

Nanocellulose:

Surface charge: The surface charge of unmodified nanocellulose is low, and its surface is mainly composed of hydrophilic hydroxyl groups, and the charge is not obvious. Due to the lack of sufficient negative charge, unmodified nanocellulose is prone to flocculation or precipitation in aqueous solution, especially in high concentrations or high electrolyte environments, and is prone to agglomeration.

Stability: Unmodified nanocellulose has poor stability in water, especially when the electrolyte concentration is high, precipitation or aggregation is prone to occur.

Carboxylated modified nanocellulose:

Surface charge: Carboxylated modified nanocellulose introduces a large amount of negative charge (carboxy-COO⁻), so that its surface has a strong negative charge. Negative charge can effectively shield the mutual attraction between particles, enhance dispersion, and prevent the aggregation of nanocellulose in the solution.

Stability: Due to the enhanced surface charge, carboxylated nanocellulose is more stable in water, can resist the influence of ionic strength or pH changes, and is suitable for long-term use in complex environments. Its stability is much higher than that of unmodified nanocellulose.

4. Mechanical properties difference

Nanocellulose:

Mechanical properties: Nanocellulose is a natural polymer material with very high mechanical strength. Its nanoscale structure provides extremely strong tensile strength, rigidity and toughness. Because it is derived from natural plant fibers, nanocellulose is used as a reinforcing material in many applications and exhibits very excellent mechanical properties, especially as a reinforcing agent in composite materials.

Advantages of mechanical properties: In applications where chemical modification of the surface is not required, the mechanical properties of unmodified nanocellulose can be fully utilized and are widely used in the fields of reinforcement materials, composite materials, paper and coatings.

Carboxylated modified nanocellulose:

Mechanical properties: Carboxylation modification usually introduces some structural changes, which may cause a slight decline in the mechanical properties of nanocellulose. Because the introduced carboxyl group may loosen some of the cellulose segments, the rigidity of the nanocellulose after modification is weakened. However, this modification will not completely lose its excellent mechanical properties.

Mechanical properties balance: Although the mechanical properties may decline slightly, carboxylated modified nanocellulose still exhibits high performance in certain applications that require surface modification, such as in water-based coatings, adhesives, and composite materials. In this case, its versatility may compensate for a slight decrease in mechanical properties.

5. Differences in application areas

Nanocellulose:

Traditional Application: Unmodified nanocellulose is widely used in materials requiring high strength and toughness, such as reinforced composite materials, paper and packaging materials. In addition, it is also used in environmental protection fields such as water treatment, adsorbents, coatings and biodegradable materials.

Limitations: The dispersion and solubility of unmodified nanocellulose is poor, especially in aqueous systems, and is prone to agglomeration, which affects its performance in certain application areas (such as high concentration systems).

Carboxylated modified nanocellulose:

Extended application: Carboxylated modified nanocellulose not only maintains the high mechanical strength of unmodified nanocellulose, but also expands its water treatment, biomedicine, environmental protection, composite materials and coatings due to the negative charge on the surface. Application in the field. For example, as a carrier in aqueous coatings, adhesives, and drug delivery systems, modified nanocellulose can exhibit better dispersion and interface adhesion.

Advantages: Its extensive surface chemical activity enables it to form complexes with other molecules or metal ions, enhancing its functionality. For example, in the fields of pollutant removal and biomedical applications, carboxylated modified nanocellulose performance is better than unmodified nanocellulose.

6. Environmentally friendly and degradable

Nanocellulose:

Environmentally friendly: As a natural polymer material, unmodified nanocellulose itself has good biodegradability. Therefore, in the field of environmental protection, especially in degradable packaging materials and bio-based materials, unmodified nanocellulose Very widely used.

Degradability: Unmodified nanocellulose has good degradability and can degrade in the natural environment without causing lasting pollution.

Carboxylated modified nanocellulose:

Environmental Friendliness: Like unmodified nanocellulose, carboxylated modified nanocellulose also has excellent biodegradability. However, some modification methods may introduce some chemicals and require further evaluation of their potential environmental impact.

Degradability: Although new chemical groups are introduced in the modification, generally speaking, carboxylated nanocellulose still has good degradability.

Summarize

There are significant differences in structure, performance and application fields of unmodified nanocellulose and carboxylated modified nanocellulose. Carboxylated modified nanocellulose has improved its water solubility, dispersion, stability and charge properties due to the introduction of carboxylate (–COOH) functional groups on the surface, making it more widely used in aqueous systems and complex environments. Depending on the needs, you can choose the right type to optimize performance. Nanjing Tianlu Nano Technology Co., Ltd. is specialized in the production of nanocellulose, cellulose nanofiber filaments, vitamin nanocrystals, bacterial cellulose, cellulose nanofiber filaments (CNF), cellulose nanocrystals (CNC), bacterial cellulose ( BC) manufacturer.