Nanofibres and nanotechnology in textiles

Index

1. Introduction

2. Definition

3. History, development & origins

4. Nanofibres

5. Applications of nanotechnology in the textile branch

6. Implications and risks
6.1 Health aspects
6.2 Environmental aspects

7. Public Sponsorship

8. Conclusion

9. Sources
9.1 Internet
9.2 Literature

illustration not visible in this excerpt

1.Introduction

In former times, the European textile and clothing industry was one of the mainsprings of the industrialization and a significant branch of the economy. Nowadays, many fabrics which meet the Europeans requirements are imported from low-price competitors like China, India, Taiwan and South Korea. Various countries use the textile industry as an entrance into the industrialization. On this account the global competition of the suppliers strengthens perpetually.

“One million jobs got lost in Europe from 1993 to 2003”, explained William Lakin, general director of the European textile association Euratex (F.A.Z., 14.06.2005, Nr.135/Seite 11). Nevertheless, there are still 2,5 million people engaged all over Europe and the textile branch turns about 215 billion euros.

Increasing competition and the enormous demand for new materials, is forcing the industry to restructure and modernise.

Significant restructuring has taken place over the last decade, however, there is a general recognition that producing traditional apparel products may no longer be sufficient to sustain a viable business, and the EU textile industries may have to move towards more innovative, high quality products in order to differentiate themselves and compete. The key areas for increased competitiveness are expected to be Information Technology, Biotechnology and the emerging Nanotechnology.

2. Definition

Nanotechnology is a modern sector of natural scientific research between physics, chemistry and molecular biology which deals with the exploration and manipulation of devices with dimensions measured in nanometers (figure 1).

size of stuctures

illustration not visible in this excerpt

figure 1: Development of the physical technologies over the last 60 years and trends in chemical and biological sciences.

While structures in the technological area (red curve) became smaller, faster and cheaper, chemists (green curve) tried to develop more complex and larger molecular structures and systems. In biotechnology (blue curve), smaller functional systems have been manufactured (e.g. biological sensors). In the range of the nanometer scale (vertical axis) the classically separated scientific disciplines (physics, chemistry, biology (blue curve)) are merged (black circle). The outcome of this are new fields of work and markets, e.g. in the automobile manufacturing, the pharmaceutical industry and of course the textile branch. (http://www.akademienunion.de/_files/akademiejoumal/2004-1/AKJ_2004-1-S-48- 54_fuchs.pdf)

Objects of research are structures which are at least in one dimension smaller than 100 nm. The task of nanotechnology is the systematic arrangement of nanoparticles within a functional system (image 1).

illustration not visible in this excerpt

image 1: Nanoparticles are regularly arranged within afunctional system (left side). The molecules on the right side are disordered. Therefore, no functional system occurs. (http://www.hohenstein.de/)

The prefix “nano” derives from the Greek word “nános” which means “dwarf”.

One nanometer (nm) is one billionth of a meter. To put that scale in context, the comparative size of a nanometer to a meter is the same as that of a marble to the size of the earth.

Basic structures of nanotechnology are: point-shaped structures that are smaller than 100nm in all three dimensions (e.g. nanocrystals and molecules), linear structures which are at the nanoscale in two dimensions (e.g. nanofilaments and nanotubes), layer structures that are only in one dimension at the nanoscale, “inverse” nanostructures (pores) and finally complex structures like dendrimers (image 2).

illustration not visible in this excerpt

image 2: carbon nanotube (right), fullerene (middle), dendrimer (left) (www.cit-wfg.de/download.php?datei=061212085856.pdf)

Two main approaches are used in nanotechnology. On the one hand, there is the “bottom-up” approach which is used in the nanotechnological field of chemistry. In this case, composites of molecules like dendrimers are constructed out of many single molecules. On the other hand, there is the “top-down” approach which is dominated by physical techniques. Based on micro technology, nano-objects are constructed from larger entities without atomic-level control. Nanotechnology is considered to be the key technology of the forthcoming decades which opens up new market potentials. Innumerable research establishments throughout the world. Also the German Government has realized the compelling potential benefits of nanotechnology years ago. On this account, over thirty countries are now initiating national research and development initiatives.

In the textile branch, nanotechnology intends to produce novel materials which offer new properties and functions. At this stage, nanomaterials are used within customary products like cosmetics, stain resistant clothing or protective coatings.

3. History, development & origins

Although nanotechnology is a relatively recent development in scientific research, the development of its central concepts happened over a longer period of time.

The physicist Richard Feynman is known as the “father” of nanotechnology due to his speech "There's Plenty of Room at the Bottom" at an American Physical Society meeting at Caltech on December 29, 1959. He forecasted, that it will be possible to influence and move single atoms.

The term "nanotechnology" was first defined by Tokyo Science University Professor Norio Taniguchi in a paper in 1974: “Nanotechnology mainly consists of the processing of, separation, consolidation, and deformation of materials by one atom or one molecule."

In 1986, Dr. K. Eric Drexler popularized the term through speeches and the books “Engines of Creation: The Coming Era of Nanotechnology“ (1986) and “Nanosystems: Molecular Machinery, Manufacturing, and Computation” (1992). In his definition, nanotechnology is confined to the construction of complex materials from single atoms. Drexler's vision of nanotechnology is often called "Molecular Nanotechnology" (MNT) or "molecular manufacturing".

Today, nanotechnology is not used in this narrow sense anymore. It has been extended to include structures with dimensions up to 100nm.

4. Nanofibres

Nanofibres and nanotubes made of carbon are fundamental components of nanotechnology. On that account, it is tried to manufacture them as precisely as possible all over the world.

So far, it was however difficult because the procedure of their emergence could not be observed exactly and therefore remained puzzling.

Today, those extremely subtle structures can be regarded by new, highly suspending electron microscopes while shaping.

Testing in the size of 0.14 nanometres can be examined using a transmission electron microscope (TEM). By comparison: a human hair has a diameter of 10,000 to 100,000 nanometres (image 3).

One method of "spinning" nanofibres is letting carbon enriched methane steam react with nanoparticles consisting of nickel as catalyst at a temperature of 500 degrees Celsius.

[...]