ISO/TR 18401:2017 ナノテクノロジー— ISO / IEC80004シリーズから選択された用語のわかりやすい説明 | ページ 7

4.3.1 一般

ISO 定義:

ナノマテリアル (図 3 を参照) には以下が含まれます。

• 1)ナノスケールの内部構造または表面構造を持つ材料であるナノ構造材料。他の
• 2)少なくとも 1 つの外部寸法がナノスケールであるナノオブジェクト。

ナノ材料は、自然発生、製造、または偶発的なもの、つまり、プロセスの意図しない副産物として生成されたナノオブジェクトである可能性があります。

たとえば、ナノマテリアルは次のようなものです。

• もみ殻で形成されたシリカなどの生物源から自然に発生する。
• 火山の噴火から放出されるナノ粒子など、地質学的発生源から自然に発生する。
• 製造されたナノ材料、例えばナノ二酸化チタン。
• 生物由来のセルロースナノマテリアルなど、生物源から製造されたもの。また
• 偶発的なナノマテリアル、例えば溶接煙粒子、薪ストーブの使用時に発生する煙、車のディーゼル排気。

4.3.2.1 一般

ISO 定義:

ナノオブジェクトは現在、そのサイズと形状に基づいて分類されています。

ナノ オブジェクトは、通常、ナノスケールで制約される寸法の観点から記述またはグループ化されます。

• 一次元（ナノプレート）;
• 二次元（ナノチューブを含むナノファイバー）;また
• すべての 3 つの次元 (ナノ粒子と量子ドット)

たとえば、ナノプレートはナノスケールの 1 つの次元を持ちますが、ナノスケールよりも大きくなる可能性のある他の次元を持ちます。 「一次元」ナノ物体は、ナノスケールの一次元を有する一般的に理解されている「三次元」物体である。

4 Terms and explanations

4.1 Nanoscale, nanoscale phenomenon

ISO definitions:

“Nanoscale” is an agreed descriptor principally referring to the size range 1 nm to 100 nm, where 1 nm is 10⁻⁹ m (0,000000001 m). To appreciate the relative size of the nanoscale dimension, Figure 1 illustrates the ratio of 1 m to 1 nm as approximately the same as between planet Earth and a cherry. Atoms are in the size range 0,1 nm to 0,4 nm and DNA is approximately 2 nm in width.

The range 1 nm to 100 nm is where changes in properties ascribed to materials in the nanoscale are likely to be observed. These changes can occur either because of the increased surface area when an object is reduced into the nanoscale or because the confined size enables different physical and chemical phenomena to occur. Thus Figure 2 illustrates how the surface area increases when an individual object is split into an assembly of smaller objects.

Materials in the nanoscale can exhibit properties with new or enhanced characteristics. The properties that can change at the nanoscale might include:

• optical (e.g. colour)
• mechanical (e.g. tensile strength)
• chemical (e.g. catalysis)
• electrical (e.g. conductivity).

The new or enhanced properties attributable to the nanoscale are described as “nanoscale phenomena”.

4.2 Nanotechnology

ISO definition:

Although scientists and craftsmen have manipulated matter at the nanoscale for centuries (e.g. stained glass windows), it was not until specialized forms of microscopy (e.g. electron microscopy) were developed that we could visualize materials in the nanoscale and more precisely control their structure.

Nanotechnology can improve a product or process in a way that would not be possible otherwise.

4.3 Nanomaterials

4.3.2 Nano-objects

4.3.2.2 Properties, size and shape

The term “nano-object” is the collective or general term, which encompasses the wide range of shapes and sizes of objects in the nanoscale (e.g. nanoparticle, nanofibre and nanoplate, see Figure 3). Nano-objects therefore also encompass a broad spectrum of shapes. The ISO definition of nano-object and related terms is based on size and shape and not on any particular property or properties because those would be impossible to capture in specific definitions.

ISO definition:

The term nanoparticle depicts a subset of nano-objects with all external dimensions in the nanoscale. If a nano-object has one or two dimensions outside the nanoscale they have a different shape and are categorized as nanofibres or nanoplates, as appropriate. It is also important to note that nanotubes are hollow nanofibres and are therefore nano-objects.

An area of widespread application is nanoelectronics, which is the field of science and technology concerned with the development and production of functional electronic devices with nanoscale components.

4.3.3 Nano-objects, agglomerates and aggregates

ISO definitions:

Many nano-objects tend to combine into larger particles, which are known as either agglomerates or aggregates (see Figure 4).

The difference between agglomerate and aggregate is based on the strength of the bonding between constituent nano-objects. An aggregate of nano-objects is essentially a discrete nanostructured particle and it is virtually impossible to release its constituent nano-objects without fracturing the component material. However, an agglomerate can more easily release its constituent nano-objects because of its relatively weaker bonding. It is the number of weaker bonds in agglomerates that determine the ability to release the constituent nano-objects. Agglomerates can be made up of nano-objects or aggregates of nano-objects (see Figure 4).

The size of an aggregate or agglomerate can be larger than the nanoscale.

When nano-objects are introduced into a medium they can naturally agglomerate or aggregate. For example, commercially available nanomaterial powders are usually in the form of aggregates or agglomerates.

4.3.4 Nano-enabled, nano-enhanced

ISO definitions:

Nanomaterials are typically used to achieve new or improved functionality of a process or product. “Nano-enabled” or “nano-enhanced” describe devices or systems that utilize some aspect of nanotechnology to create or enhance functionality. “Nano-enabled” refers to functionality that is not possible without nanotechnology whereas “nano-enhanced” refers to the improvement of an existing function.

Examples of products that can be nano-enabled or nano-enhanced include:

• self-cleaning reflectors, glass and other surfaces (e.g. concrete);
• self-healing or repairing (e.g. car paints);
• food – production, processing, packaging, quality control and distribution;
• pharmaceuticals, e.g. drug diagnostics and delivery;
• medical devices, e.g. rapid HIV testing devices;
• sporting goods, e.g. lightweight bicycle frames with increased strength-to-weight ratios;
• energy production, e.g. nanostructured organic solar cells;
• abrasion-resistant finishing board using cellulose nanomaterials;
• lubricants and filters; and
• water purifying membranes.

Processes or services, such as catalysis, water filters or electronics (e.g. GPS navigation) can also be enhanced or enabled by the use of nanotechnology.

4.4 Nanocomposites

ISO definitions:

Composite materials are common in industry, including nanocomposites where nano-objects form one or more phases of the composite. Materials composing the matrix could be a different chemical composition or material phase.

Examples include:

• a polymer matrix containing nanoparticles added to improve strength, e.g. tyres;
• concrete incorporating carbon nano-objects in order to improve toughness; and
• electronic memory made of magnetic wires inside anodic alumina matrix.

4.5 Nanolayers, nanocoatings and nanofilms

ISO definitions:

Ordered structures such as films and layers are useful for a number of purposes, e.g. food packaging which can include layers to prevent oxidation, ink migration as well as enhance shelf-life and other quality attributes. There can be many layers with individual layer thicknesses of just a few nanometres. Nanostructured surfaces have been developed where a patterned structure on the surface of a component can have a major influence on function including self-cleaning, friction and optical properties.

A nanofilm is a layer with a thickness in the nanoscale, which can exist on its own as a single unit and can be flexible or rigid. A nanocoating exists only in combination with its substrate; it cannot have an independent existence. All are layers in the common use of the word. The terms “foil”, “sheet” and “film” are sometimes used interchangeably. A membrane is a film separating two phases.

Examples include:

• anti-reflection layers that can enhance a spectacle lens;
• nanocoatings on pharmaceutical products to regulate dissolution;
• enhanced mechanical properties such as hardness;
• coatings to control heat loss through windows;
• ceramic coatings for wear resistance;
• coated dental implants; coated hip replacements for increased lifespan; and
• anti-slip surfaces made by texturing the surface.

Bibliography