Specific Material Research

Chris Powitzky and Mark Buchanan

What is Nanotechnology?

Nanotechnology is currently all the rage. Accordingly, both the term and the concept are much over-used. Nevertheless few people, and even fewer designers, really know what nanotechnology actually is and what it is good for. It is, however, most definitely more than just a passing fashion. In fact, at present nanotechnology is still a fledging science but one that has been forecast an extremely promising future with the potential to change the world around us. 

"Nano" derives from the Greek word nanos (Latin nanus) meaning "dwarf - so begin many articles on nanotechnology and this book is no exception. A nanometre (nm) is a millionth of a millimetre (1/1,000,000mm = lO'^mm) or a billionth of a metre (1/1,000,000,000m = IQ-^m). It is an 80,000th of the diameter of a hair (the figure varies between 50,000th and 100,000th) and is the same size as about five to ten atoms. Given that a billion nanometers equal a metre, it should be clear that we are concerned here with the most minute of dimensions. The wavelength range of visible light is approximately 400 to 800 nm and as the light scattered by smaller particles reduces significantly, particles of such a small size become effectively invisible. "Nano" cannot, therefore, be seen with the naked eye. 

Comparisons help us to better comprehend the scale of the dimensions involved - a common comparison is that the proportion of a nanometre to a football is about the same as that of a football to the earth. If one were to spread a single drop of water over an area of 1 m^ it would be 1 nm thick. Human fingernails grow at a rate of I nm per second.

In the famous film "Powers of Ten" by the designer-duo Charles and Ray Eames, a classic film in the field that has now attained cult status, the viewer is taken on a journey through the powers of ten of the cosmos, illustrating the differences in dimension. The film, made in 1977, is most worthwhile and can still be ordered from the Eames Office in the USA via the internet.

 A clear and generally applicable description on an international level has not as yet been defined for the term "nanotechnology", but in most cases it serves as a general heading for all manner of analyses and material investigations at nanoscale. Generally speaking, nanotechnology therefore describes any activities at a magnitude of less than 100 nm. This threshold reflects the fact that at this point there is a "kink in nature". It is at this size that the properties of solid materials change, for example gold changes its colour to red. At 100 nm and below things start to become particularly interesting. 

The definition given by the German Federal Ministry of Education and Research (BMBF) summarises nanotechnology as follows: "Nanotechnology refers to the creation, investigation and application of structures, molecular materials, internal interfaces or surfaces with at least one critical dimension or with manufacturing tolerances of (typically) less than 100 nanometres. The decisive factor is that the very nanoscale of the system components results in new functionalities and properties for improving products or developing new products and applications."

"Research and technology development at the atomic, molecular or macromolecular levels, in the length scale of approximately 1 100 nanometer range, to provide a fundamental understanding of phenomena and materials at the nanoscale and to create and use structures, devices and systems that have novel properties and functions because of their small and/or intermediate size. The novel and differentiating properties and functions are developed at a critical length scale of matter typically under 100nm. Nanotechnology research and development includes manipulation under control of the nanoscale structures and their integration into larger material components, systems and architectures. Within these larger scale assemblies, the control and construction of their structures and components remains at the nanometer scale. In some particular cases, the critical length scale for novel properties and phenomena may be under Inm (e.g., manipulation of atoms at ~ 0.1 nm) or be larger than 100nm (e.g., nanoparticle reinforced polymers have the unique feature at ~ 200-300 nm as a function of the local bridges or bonds between the nanoparticles and the polymer)."

Nanoparticles measure only a few nanometres and can consist of just a few or several thousand atoms. The material out of which nanoparticles are made is nothing out of the ordinary. The basic material of nanoparticles can be organic or inorganic, for example silver or ceramic. They can be elements such as carbon, or compounds such as oxides, or they can be a combination of different compounds and elements. The key characteristic is not the material itself but the size of the particles. In comparison to their size nanoparticles have a vast surface area. At this size, a relatively inert material can become highly reactive and therefore potentially interesting for many different uses, for example as a catalyst. In addition nanoparticles have a tendency to form agglomerations. Nanoparticles with less than 1000 atoms, i.e. very small nanoparticles, are called clusters.

Nanoparticles are invisible due to the fact that they are smaller than the wavelength of visible light and therefore unable to scatter light. For this reason, a solution that contains a 60% proportion of solids in the form of nanoparticles can still be transparent.

Aside from synthetic production, nanoparticles are also present in natural materials, for example in clay, a constituent of loam, which contains a high proportion of natural nanoparticles. These are responsible for properties such as frost-resistance, durability and strength. Another example from nature is mother of pearl, whose high durability is also attributable to its nanostructure.

The ultra-thin and invisible nanocoatings, whose applications are of particular interest to designers, generally have a thickness of 5 lOnm. The optimum thickness of each coating, for instance when spray-applied, comes about automatically, a phenomenon that is termed "self-organisation". Each square centimetre then contains billions of nanoparticles.

The manufacture of such ultra-thin coatings with the help of chemical techniques uses a so-called "bottomup" approach, i.e. one develops from the smallest size to larger sizes, beginning with the atom and finishing with the desired product. By comparison, the conventional manufacture of raw materials generally uses a "top-down" approach, in which a material is reduced, for instance by grinding down, to the desired size. Nanotechnology in general, i.e. when used not solely for coatings, employs both such approaches. 

Nanoparticles can be used in solutions, which despite a high proportion of solids appear transparent. Another application is the use of nanopowders. Nanocoatings can be applied using traditional means such as spraying and dipping.

The shimmering blue colour of butterfly wings is caused by light reflections rather than colored pigments. The wings are covered with nanostructured scales that reflect light and through a process of interference cancel out all colors except blue. Such colourings are a product of the laws of physics and cannot fade. For this reason, researchers attempt to replicate this effect artificially with paints or colored films.

Gold nanoparticles are regarded as the ideal constituent material for nanostructures. Their unique optical, electronic and catalytic properties are especially interesting.

Examples of the Nanometer scale

Single-walled carbon nanotubes can be extruded to form macroscopic fibers. This image shows a single carbon nanotube isolated and enclosed In a molecule. Under particular conditions carbon nanotubes have been found to exhibit fluorescent properties. In the near infrared range, light is absorbed and emitted.

Architectural Applications of Nanomaterials

THE LOTUS EFFECT:

Characteristics - Microscopically rough, not smooth. Hydrophobic - water trickles off. 

ARCHITECTURE  Renner Hainke Wirth Architekten, Hamburg, Germany 

CLIENT  Joint ownership Martens per Schumann Immobilien KG 

PRODUCT  Lotusan, self - cleaning paint (Lotus-Effect) 

MANUFACTURER  Sto

COMPLETION  2007

AREA  3685 sq meteres

As with earlier renovation projects, the architects chose to use self-cleaning facade coatings for the irrenovation of a 1970s housing estate. The estate consists of a high-rise block as well as a number of multi-story terraced housing blocks. The renovated elevations are clad in a composite thermal insulation system with a pigmented render coating in light beige and red. As part of the redesign, window recesses were given color high- lights, the house entrances were made more prominent, wired glazing was replaced with transparent clear glass, bathrooms were given windows and the under sides of balconies were painted in color. The differentiated coloring of the new facades is most apparent. Warm colors in a palette between yellow and red l end the entire estate a pleasant and unified appearance. As regards the self-cleaning function, Hamburg proves to be an ideal location as there is no lack of rain.

EASY-TO-CLEAN:

Characteristics - Smooth surfaces with reduced surface attraction. Surface repellence without using the Lotus-Effect. 

ARCHITECTURE  Carlos Martinez Architekten, Widnau SG, Switzerland 

LIGHT DESIGN  Vogt & Partner, Winterthur, Switzerland 

ART  Pipilotti Rist, Zurich, Switzerland

CLIENT  Raiffeisenbank St. Gallen 

PRODUCT  Nano-Vitro

MANUFACTURER  NanoSys 

COMPLETION  2005 

In spring 2005, the carefully designed urban ensemble of the Raiffeisenbank was completed in the centre of St. Gallen. The outdoor spaces are designed as an "urban lounge", the winning project from an earlier ideas competition. The project is as novel as it is radical, covering the jagged urban space of the neighbourhood in carpet - a tongue-in-cheek public living room for lounging around in. "Lightbubbles" that appear to float in the lounge provide diffuse light. With a diameter of 3 m and a mother-of-pearl-like fibreglass covering made of Scobalit, the lights both function as illumination and create an atmospheric mood through coloured light. The surface is covered with a dirt, snow and ice-repel- 

lent coating, which is ultra-thin, transparent and unaffected by UV light. Its anti-adhesive function ensures that dirt, which with time would impair the intensity of the light, is washed away with the rain. The lights are also equipped with fan heaters, a "plan B" for melting snow and ice. The coating has a limited lifetime, and must be renewed after several months. 

THERMAL INSULATION: VACUUM INSULATION PANELS (VIP):

Characteristics - Maximum thermal insulation, minimal insulation thickness. 

ARCHITECTURE  Rolf Disch, Freiburg, Germany 

ART  Erich Wi esner , Herbert Dreiseitl 

CLI ENT  Solarsielung GmbH 

PRODUCT  Vacuum insulation panel

COMPLETION  2006

AREA   6500 sq meters

The mixed - useresidential and commercial centre is situated next door to a solar housing estate and provides new amenities that were previously not locally available. The Sonnenschiff's forward-looking concept combines an economic and efficient use of energy with the use of regenerative energy sources, to the extent that the building produces more energy than it consumes. Solar and wind energy as well as geothermal warmth are utilised and natural, regenerative and recyclable building materials are employed Vacuum insulation panels (VIPs) have been used for insulation and phase change material (PCM) latent heat storage systems for regulating indoor temperatures - both highly energy efficient systems. The V1Ps constitute  the insulation of the external walls and window parapets as well as the ventilation flaps on the main facade. Compared with other insulation materials of  the same thickness, they offer ten times better insulation. PCMs in the walls and roof construction store ambient heat as they change material state . As such they help keep rooms cool and passively regulate the indoor air temperature . The concept is rounded off by an ingenious light, ventilation and heating concept . The implementation of a colorful artistic concept gives the building an eye-catching appearance.

THERMAL INSULATION: AEROGEL

Characteristics: High-performance thermal insulation. Light and airy nanofoam.

ARCHITECTURE  Agence MA, Murail Architectures, Nantes, France 

CLIENT  City of Carquefou 

PRODUCT  Multi-wall panels with Nanogel filling 

MANUFACTURER  Cabot Corporation

COMPLETION  2006

AREA OF SPORTS HALLS  3360 sq meter

FACADE SURFACE  1450 sq meters

All elevations of this sports complex have been clad with aerogel-filled multi-wall polycarbonate panels. With this construction the architects voluntarily com- ply with the guidelines set down by the French "green" environmental initiative Haute Qualite Environnementale (HQE). Additional solar protection is unnecessary, allowing a clean and unified appearance uninterrupted by brise-soleils or louvres. Natural daylight provides an even and glare-free illumination of the indoor space, and additional indoor lighting is not necessary during the day There are no cast shadows that could be distracting for certain sports. The thermal insulating effect of the aerogel panels also reduces the heat demand: a 25 mm thick panel has a U-value of 0.89 W/m^K and is available in 1.05 m wide panels of up to 6 m in length. 

FIRE-PROOF MATERIALS:

Characteristics - Highly efficient fire protection. Light and transparent. 

ARCHITECTURE  Murphy/Jahn, Chicago, IL, USA 

CLIENT  Deutsche Post Bauen

PRODUCT  SGG Contraflam fire safety glass 

MANUFACTURER  Vetrotech SaintGobain 

COMPLETION  2005 

AREA  90,000 m2 gross floor area

The landmark 160 m high office tower in Bonn, the former capital city of Germany on the River Rhine, accommodates more than 2000 members of staff. The oval tower's fagade is clad in high-tech transparent glazing and transparent materials are also used throughout its interiors: glazed partitions, glazed staircases and glazed connecting bridges are central elements of the interior design concept. A fire safety glass with a particularly slender profile was selected for the project. Space, form, construction and materials are carefully coordinated, resulting in a harmonious overall concept. 

ANTIBACTERIAL:

Characteristics - Bacteria are targeted and destroyed. The use of disinfectants can be reduced. Supports hygiene methods - especially in health care environments. 

ARCHITECTURE Schweitzer + Partner, Braunschweig, Germany 

CLIENT Harzkliniken, Goslar 

PRODUCT "Hydrotect" tiles, photocatalytic surface with antibacterial effect 

MANUFACTURER Agrob Buchtal Architectural Ceramics, Deutsche Steinzeug AG 

COMPLETION 2005 

In both operating theatres, the floors and walls have been clad in photocatalytic tiles. Hygiene is of primary importance in operating theatres and antibacterial tiling contributes to lessening the risk of infection. In the Klinikum im Friedrichshain, the architects have gone one step further and minimised the amount of tile joints, lessening weak points where bacteria can settle and lending the room a calmer appearance. Large- format tiling is more difficult to lay, and a conventional tile format was chosen for the high-tech antibacterial tiles used in the Harzkliniken. The light-colored grouting contrasts pleasantly with the fresh green tiling.