With the rapid development of renewable resources and green and environmentally friendly materials, nanocellulose (Nanocellulose) has gradually become a hot topic in scientific research and industrial fields due to its advantages such as lightweight, high strength, renewable and degradable. Among them, TEMPO oxidation modification , as an efficient and controllable surface functionalization method, gives nanocellulose more performance and application potential. This article will introduce the principles, characteristics and typical applications of TEMPO oxidized nanocellulose from a popular science perspective.

What is TEMPO oxidation?

TEMPO (2,2,6,6-tetramethylpiperidin-1-oxygen radical) is an organic radical catalyst. Under alkaline conditions, TEMPO works together with sodium hypochlorite (NaClO) and sodium bromide (NaBr) to selectively oxidize the primary hydroxyl group at the C6 position of cellulose molecule to carboxyl (–COOH) 。
. This reaction has the following advantages:

• Strong selectivity: mainly acts on the C6 position and does not destroy the cellulose main chain;

• Gentle conditions: can be carried out at room temperature, green and environmentally friendly;

• Product controllable: The degree of oxidation can be controlled by adjusting the reaction conditions.

Characteristics of TEMPO oxidized nanocellulose

After TEMPO oxidation modification, nanocellulose has the following outstanding characteristics:

1. Surface charge : After the carboxy group is introduced, the nanocellulose is negatively charged, and the dispersion is significantly enhanced;

2. Strong interface compatibility : carboxyl groups can form hydrogen bonds or electrostatic effects with polymers, proteins, metal ions, etc., enhancing the performance of composite materials;

3. More controllable size : oxidation treatment helps to obtain uniform fibers with diameters of 3–10 nm and lengths of hundreds of nanometers;

4. It can be further functionalized : the carboxyl group is the active site, and graft modification, cross-linking or metal ion complexing can be performed.

Application of TEMPO oxidized nanocellulose

1. Composite reinforcers
   are added to plastics, rubbers and hydrogels to enhance mechanical strength, toughness and durability.

2. The film made of TEMPO oxidized nanocellulose in food packaging material
   has good oxygen barrier properties and transparency, which helps to extend the shelf life of food.

3. In the field of water treatment and environmental protection,
   carboxylic groups can adsorb heavy metal ions and dye molecules, and are used for wastewater purification and environmental governance.

4. Pharmaceuticals and Biomedicine
   , as drug carriers and tissue engineering scaffolds, exhibit excellent biocompatibility and degradability.

5. Energy storage and electronic devices
   are used in battery separators and supercapacitors to improve conductivity and cycle life.

Prospects

Due to its gentle preparation method, outstanding performance and wide application, TEMPO oxidized nanocellulose is considered an important direction for future green new materials . With the scale and cost optimization of the preparation process, it is expected to achieve larger-scale industrial applications in the fields of packaging, new energy, biomedicine, environmental governance, etc.