New Materials: Research Shows That The Color Change Characteristics Are Usually Determined By The Special Properties Of Its Molecular Structure

In the visible spectrum, transparency means that the color can let all wavelengths of light pass through, so transparent objects have no color themselves.

In practical applications, transparency usually refers to a colorless or very nearly colorless state, allowing light to completely pass through without absorbing or reflecting light. For example, pure water and some types of glass are transparent.

As for "color change", this concept usually refers to the characteristics that can change color or present different colors under different conditions. This phenomenon can be observed in some materials or objects, such as:

1. Chameleon: This reptile can change the skin color according to the surrounding environment or emotional changes.

2. Color changing ink: some inks will change color according to temperature, pH value or other environmental factors.

3. Light variable pigments: These pigments will change color in the sun or in certain types of light, which are common in some safety signs and anti-counterfeiting technologies.

4. Color changing clothing fabrics: some clothing fabrics use special dyes or coatings, which can change color under temperature changes or light irradiation.

5. Some chemicals: The color of some chemicals will change during chemical reaction.

It should be noted that no color is "transparent and color changeable", because transparency means no color, while color changeable means that color will change. These two characteristics are usually separate.

There are indeed some substances that can appear transparent or colorless under certain conditions, but can change color under other conditions. These substances usually contain special chemical composition or structure, making them sensitive to environmental changes (such as light, heat, electric field, etc.).

Here are some examples:

　　1. Photochromic materials: These materials will change color under the irradiation of ultraviolet or visible light. A common example is photochromic glasses, whose lenses are transparent indoors, but darken outdoors in the sun, thus providing a sunshade effect.

　　2. Thermochromic materials: These materials change color with temperature. For example, some tableware and toys used by children use thermochromic paint. When the food or drink is overheated, the color will change, reminding parents to pay attention.

3. Electrochromic materials: under the action of electric field, the color of such materials will change. This feature is applied to smart windows and certain types of displays.

4. pH indicator: some dyes or compounds will show different colors in solutions with different pH values, which are commonly used in chemical experiments and industrial process control.

　　5. Liquid crystal: Liquid crystal materials will change their molecular arrangement under different temperature, pressure or electric field conditions, thus changing the light transmission characteristics, showing different colors and transparency. The liquid crystal display (LCD) works on this principle.

6. Some metal complexes: Some metal complexes will change color under different chemical environments or lighting conditions, which is called coordination chemistry of metal complexes.

7. Hydrogel: Some hydrogel materials will change color when absorbing water or losing water. This feature can be used to make smart textiles or sensors.

The color change characteristics of these materials are usually determined by the special properties of their molecular structures. The changes of their optical properties under different conditions make the color display different. These features are very valuable in many high-tech applications, such as sensors, smart materials, and data storage devices.