Research on the surface groups and their modification of nanocellulose

Nanocellulose is a nano-scale material extracted from natural cellulose. It has high specific surface area, excellent mechanical properties and biodegradability, and its surface groups play an important role in the properties and applications of nanocellulose. By modifying and modifying its surface groups, the application performance of nanocellulose in various fields can be significantly improved. This paper will focus on the types and functions of nanocellulose surface groups and their modification methods.

Types of surface groups of one nanocellulose

Functional groups on the surface of nanocellulose are mainly derived from the hydroxyl groups ( -OH ) in cellulose molecules and other groups introduced by hydrolytic oxidation or other chemical modification. Common surface groups include:

1. Hydroxyl ( -OH)

The surface of nanocellulose mainly contains a large amount of hydroxyl groups ( -OH ), which is the natural functional group of cellulose molecules. These hydroxyl groups impart high hydrophilicity and good solubility to nanocellulose, allowing them to be dispersed more uniformly in the aqueous phase. The hydroxyl groups also provide reactive activity for further chemical modification of nanocellulose.

2. Aldehyde group ( -CHO)

Through oxidation treatment, the surface of nanocellulose can introduce aldehyde group ( -CHO ) and aldehyde group can significantly improve the reactivity of nanocellulose, promote the binding with other materials, and expand its application in composite materials

3. Carboxylic ( -COOH)

Carboxyl groups ( -COOH ) are usually introduced to the surface of nanocellulose by TEMPO oxidation and other technologies. The introduction of carboxyl groups increases the negative charge density of nanocellulose, making it better dispersibility and compatibility. In addition, the presence of carboxyl groups can also improve the interface bonding of nanocellulose with other materials (such as metal polymers, etc.).

4. Amino ( -NH2)

Amino groups ( -NH2 ) can be introduced into nanocellulose surface amino groups through amination reaction or other chemical modification methods. They can significantly improve the hydrophilic dispersion of nanocellulose and compatibility with other organic materials. They are widely used in the fields of biomedical drug delivery and sensors.

Function of the surface group of two nanocellulose

The surface groups of nanocellulose not only directly affect their surface properties, but also determine their application performance in different fields. The main functions include:

1. Improve dispersion

The polarity and charge characteristics of the nanocellulose surface groups determine their dispersion in the aqueous phase or solvent. For example, the introduction of carboxyl groups can significantly improve the dispersion of nanocellulose in water and avoid agglomeration between particles.

2. Enhanced compatibility

By introducing different surface groups, the compatibility of nanocellulose and other materials can be enhanced. For example, amino groups greatly improve the compatibility of nanocellulose and polymer composite materials, which promotes the improvement of the mechanical properties of composite materials.

3. Promote interface integration

The surface groups of nanocellulose can form chemical bonds or physical adsorption with other materials, thereby enhancing interface binding force. In composite materials, the introduction of surface groups can effectively improve the interface strength between cellulose and matrix materials and improve the mechanical properties of composite materials.

4. Improve responsiveness

Certain surface groups (such as aldehyde groups) can significantly enhance the chemical reactivity of nanocellulose and expand their application in drug delivery catalysis and other fields. Through the introduction of surface groups, nanocellulose can react with various functional molecules to form new materials with multiple functions.

Method for modifying the surface group of three nanocellulose

In order to expand the application field of nanocellulose, researchers have adopted a variety of methods to modify their surface groups. Common modification methods include:

1. TEMPO oxidation method

Through TEMPO ( 2,2,6,6- tetramethylpyridine oxide) oxidation method, a large amount of carboxyl groups can be introduced on the surface of nanocellulose . This method not only improves the hydrophilicity and dispersion of cellulose, but also enhances its performance in composite materials.

2. Acid hydrolysis method

Acid hydrolysis is to hydrolyze natural cellulose through concentrated acid, remove amorphous regions, and obtain nanocellulose acid hydrolysis with a high crystallinity. During the hydrolysis process of nanocellulose acid, the surface groups of cellulose will undergo certain changes, mainly by increasing carboxylic and aldehyde groups, and improving its surface functionalization.

3. Amination reaction

Amination reaction introduces amino groups through amino chemical reactions, allowing nanocellulose to form a stronger combination with biomolecules or polymers, and is widely used in drug delivery and biomedical fields.

4. Physical adsorption method

Physical adsorption method adsorbs functional molecules or ions to the surface of nanocellulose through simple physical actions such as electrostatic adsorption. This method is simple and low-cost and is suitable for large-scale production.

Application prospects of four-nanocellulose surface groups

The surface group modification of nanocellulose has enabled it to show a wide range of application prospects in a variety of fields, including but not limited to:

High-performance composite materials : Modified nanocellulose can form a stronger combination with polymer metals and other materials, improving the strength, heat resistance and electrical conductivity of composite materials.

Biomedical field : Surface-functionalized nanocellulose shows great application potential in drug delivery tissue engineering and wound dressings

Environmentally friendly materials : Nanocellulose, as a green and environmentally friendly material, has wide application in water treatment waste recycling and other aspects.

Sensors and electronic devices : Due to their excellent electrical properties and adjustable functional characteristics after surface modification, nanocellulose has broad application prospects in high-tech fields such as sensor electronic devices.

Five conclusions

The surface groups of nanocellulose play a crucial role in their performance and applications. Through different surface modification technologies, the dispersion compatibility and reactivity of nanocellulose can be significantly improved, and its application in high-performance materials, biomedical and environmental protection fields is expanded. With the continuous deepening of research, nanocellulose will become an important part of future materials science and green technology.