Comparison of TEMPO oxidized nanocellulose treatment method and other chemical modification methods

As nanomaterials are increasingly widely used in various fields, nanocellulose has attracted high attention from scientific research and industry due to its excellent mechanical properties, biocompatibility and environmentally friendly characteristics. Among them, TEMPO (2,2,6,6-tetramethylpiperidine oxide) treatment is one of the common nanocellulose chemical modification methods. This article will compare the characteristics and advantages of TEMPO treatment with other major chemical modification methods to provide reference for research and application.

1. TEMPO treatment of nanocellulose

The TEMPO oxidation method is a modification method that uses TEMPO as a catalyst to oxidize the C6-position primary hydroxyl group in cellulose to a carboxy group. Nanocellulose after TEMPO oxidation treatment has the following significant characteristics:

High dispersion: TEMPO treatment introduces negatively charged carboxyl groups, which enables nanocellulose to exhibit good dispersion in water, which helps its application in aqueous phase systems and the preparation of composite materials.

High reaction selectivity : TEMPO oxidation method selectively acts on the primary hydroxyl group at C6 position, avoiding the excessive oxidation of other hydroxyl groups, thereby maintaining the stability of the cellulose structure and the mechanical properties of nanofibers.

Controllable functional group content : During the TEMPO oxidation process, the introduced carboxyl content can be adjusted by controlling the oxidation time and temperature to meet the requirements of cellulose surface charge and reactive activity in different applications.

2. Other chemical modification methods for nanocellulose

In addition to the TEMPO oxidation method , common nanocellulose modification methods also include etherification, esterification, silanization and surface grafting.

Etherification Modification : The etherification method improves its solubility and thermal stability in organic solvents by introducing ether groups into the cellulose structure. This modification method is suitable for applications where the heat resistance and hydrophobicity of the material are required.

Esterification Modification : The esterification method is to introduce ester groups or organic acid groups into the nanocellulose, thereby enhancing the hydrophobicity of the cellulose and compatibility with other organic substrates. Esterified modified nanocellulose is often used in reinforced composite materials, coatings and membrane materials.

Silenization modification : By introducing silane groups on the surface of nanocellulose, the silaneization treatment makes the nanocellulose hydrophobic and have good compatibility with inorganic materials, and is suitable for strengthening composite materials, sensors and electronic components.

Surface grafting modification : The surface grafting method is to use polymers or other organic molecules to connect to the nanocellulose surface through covalent bonds to obtain specific functionality. This modification method allows nanocellulose to have special properties in the fields of biomedicine, environmentally friendly materials, etc., such as enhancing biodegradability or chemical stability.

3. Comparison between TEMPO oxidation method and other chemical modification methods

4. Application fields of different modification methods

Application of TEMPO oxidation method : Nanocellulose after TEMPO oxidation is suitable for use in highly dispersible water-based composite materials and high-strength film materials, such as biomedical materials, food packaging and functional coatings.

Etherification Modification Application : Etherified nanocellulose is suitable for use in areas with poor solubility or requiring hydrophobic properties, such as high temperature resistant composite materials, coating materials, and plastic reinforcement materials.

Esterification modification applications : The esterified nanocellulose has better hydrophobic properties and is often used to prepare waterproof coatings, plastic fillers and film materials.

Silenization modification application : Silenized modified nanocellulose has good inorganic material compatibility and is suitable for composite materials that require water resistance and electrical conductivity, such as building materials and sensors.

Surface grafting applications : Surface graft modified nanocellulose is usually used in materials requiring specific functionality, such as drug delivery, biosensors, and smart materials.

In the chemical modification method of nanocellulose, TEMPO oxidation method is suitable for water-based systems, biomedicine, environmentally friendly materials and other fields due to its high selectivity and good water dispersion. However, other modification methods such as etherification, esterification, silylation and surface grafting also have unique advantages depending on the specific application requirements. By combining the characteristics of different modification methods, researchers can design nanocellulose materials that meet specific performance needs in a targeted manner, so that they can be widely used in composite materials, medicine, environmental protection and other fields.