Practical cases of application of nanocellulose in construction and performance stabilization of structural color materials

1. Application background

Structural color is a color expression resulting from the selective scattering, interference and diffraction of light by micro-nano structures . Unlike traditional dyes or pigments that rely on molecular absorption, its color does not fade, is highly controllable, and is environmentally friendly. It has broad application prospects in the fields of anti-counterfeiting signs, optical films, flexible displays, bionic materials, and high-end decorative materials .

However, in the engineering application process of structural color materials, the following technical difficulties are common:

The construction of micro-nano periodic structures is difficult, with insufficient repeatability and consistency. The structural stability is poor and it is easy to become unstable under drying, humidity changes or mechanical stress. The color angle is highly dependent and the structural color is uneven. Traditional inorganic or polymer structural materials have high processing costs and insufficient sustainability.

The customer hopes to build a structural color material system with controllable structure, stable color, scalable preparation and sustainable properties .

What is nanocellulose？

Cellulose nanofibers ( CNF) are ultrafine cellulose fibers made from wood. Wood pulp (papermaking raw material) produced through traditional papermaking technology is relaxed to the nanometer level. This is a new material derived from biomass, also known as nanocellulose.

CNF is as thin as a few nanometers, is considered transparent, has unique viscous properties, is light and strong, and has less deformation due to temperature changes, and is used in many fields.

● Nano = one millionth of the length of 1 millimeter

Process of producing nanocellulose CNF from wood pulp

1. The wood is crushed into small pieces and processed into wood chips (about 5cm wide and about 1cm thick)

2. Extract fiber from wood chips and make pulp in paper mill

3. The pulp is chemically treated to make it thinner and easier to loosen (chemical modification).

4. Apply high pressure to loosen wood fibers (pulp)

We chemically treat the pulp produced in the mill and introduce ionic functional groups into the cellulose, which forms wood fibers. The electrostatic repulsion of this functional group promotes nanoscale defibrillation of fibers while ensuring stable diffusion of elongated fibers in the range of a few nanometers (a few nanometers).

Fibers that are as thin as a few nanometers are thinner than the wavelength of visible light (400 nanometers to 700 nanometers), so they pass the light and become transparent.

2. Scientific principles and structural color construction mechanism introduced by nanocellulose

Nanocellulose, especially cellulose nanocrystals ( CNC ) or highly oriented cellulose nanofibers ( CNF ) , has the following key properties:

Nanoscale size and high aspect ratio

High crystallinity and excellent mechanical properties

The surface is rich in hydroxyl groups and can easily form a stable hydrogen bond network.

Naturally self-assembles to form a chiral nematic structure

1. Formation mechanism of self-assembled structural colors

Under appropriate concentration, ionic strength and drying conditions, cellulose nanocrystals can undergo self-assembly of the chiral liquid crystal phase to form a periodic spiral layered structure. When the pitch matches the wavelength of visible light, structural color is produced.

The pitch size determines the wavelength (color) of reflected light

Orientation affects color purity and brightness

Structural period stability determines color durability

2. The central role of nanocellulose in structural color

Nanocellulose plays the dual role of structural building unit + stable reinforcing skeleton in the structural color system :

As building blocks:
Constructing highly ordered, tunable photonic crystal structures

As a reinforced network:
locking microscopic periodic structures through nanofiber networks to prevent structural collapse

3. Customer core needs

Achieve controllable and repeatable structural color construction

Improve the mechanical stability and environmental durability of structural color materials

The color performance is stable, does not depend on dyes, and is not easy to fade.

Meet the application needs of films, coatings and flexible substrates

4. Application plan and process realization

1. System construction

Use high-purity nanocellulose ( CNC/CNF ) water dispersion system

Precisely control solid content and ionic strength to induce the formation of ordered liquid crystal phases

2. Self-assembly and molding

Evaporation-Induced Self-Assembly through solvent evaporation

Control the drying rate and temperature and humidity conditions, adjust the pitch and structural orientation

3. Structural stabilization treatment

Utilizing nanocellulose hydrogen-bonding network to enhance overall structure

If necessary, introduce cross-linking or composite matrix to improve environmental and mechanical stability.

5. Practical application effects

Nanocellulose structural color materials show significant advantages in practical applications:

High purity structural color performance

Color saturation and high brightness

The color comes from the structure itself and there is no risk of fading

Structural stability significantly improved

Structure remains stable under wet-dry cycles and slight mechanical stress

Good color consistency and repeatability

Strong controllability

By adjusting the size, concentration and drying conditions of nanocellulose, continuous color adjustment from blue light to red light is achieved

Suitable for multi-band structural color design

Outstanding green and sustainable attributes

With natural and renewable materials at its core

In line with the trend of green materials and low-carbon manufacturing

6. Performance comparison

index	traditional pigment system	Nanocellulose structural color system
Color source	molecular absorption	Micro-nano structure reflection
risk of fading	exist	无
structural stability	generally	高
sustainability	limited	Excellent
Controllability	limited	Highly designable

Nanocellulose structural color system

7. Case summary

This case demonstrates the dual role of nanocellulose in structural construction and stabilization in structural color materials . Through the highly ordered chiral nanostructure formed by its self-assembly, a color-stable, controllable and environmentally friendly structural color system is achieved.

This technology provides feasible and replicable solutions for the industrial application of structural colors in the fields of anti-counterfeiting materials, optical films, flexible displays, bionic materials and high-end functional coatings , and has significant scientific research value and commercial application potential.

( Schematic diagram of the three-dimensional network structure of nanocellulose )

Inquiry about nanocellulose

Nanjing Tianlu Nanotechnology Co., Ltd. ，Marketing Department , Nanocellulose Promotion Office

Address: Room 301, Building 2, Phase 3, No. 1, Yuepu Yunchuang Center, No. 6 Shuige Road, Jiangning District

Telephone:18061643560