1. Nanoscience and Materials

2. 1983 $3995 1992 $1400 2002 $480 2009 $199 These advances in technology would not have been possible without nanotechnology. Nokia Morph Nokia Morph : The Next Generation of Mobile Phones? What affects our choice of materials?

3. What do they have in common? –Both are forms of carbon. How are they different? –Appearance, hardness, conductivity. Diamond and Graphite

4. Both are forms of carbon. However, changes in the arrangement of the atoms at the nanoscale cause these materials to behave differently. Within diamond, every carbon atom is bonded to 4 other carbon atoms. Within graphite, every carbon atom is bonded to 3 other carbon atoms. Why do they behave differently?

5. This structure is known as a tetrahedron. The 4 bonds to the central carbon atom spread out evenly, so the base structure of diamond is a 3-D shape. The structure builds up because every carbon atom is bonded to another 4 carbon atoms. Diamond

6. The bonds to the central carbon atom in graphite spread out evenly, so the base structure is a 2-D shape (has length and width but no height). The structure of graphite sheets builds up because every carbon atom is bonded to 3 other carbon atoms. Bonds to 3 C atoms. The hexagonal pattern in which the atoms are arranged can now be seen. Graphite

7. As the structure continues to build up, it remains 2- Dimensional (flat). A 3-D shape is formed by the layering down of a number of these 2-D structures (called Graphite sheets) on one another. Sheets of graphite in pencil lead – taken in CRANN using a SEM. Graphite

8. Very weak forces - means that sheets can be peeled off easily. This is why graphite is soft and a useful material for pencils. These layers are kept together by a force of attraction known as Van Der Waals forces. Van der Waals forces

9. This means that a single layer of graphite is very strong. In 2004, a single layer of graphite was isolated for the first time. This single layer of graphite is known as Graphene, and consists of a sheet of carbon atoms, just one atom thick. However, the bonds IN the graphite sheet are very strong due to their partial double bond nature. Graphene

10. One of the strongest materials known - 200 times stronger than steel, but still bendable! Excellent electric conductor. Transparent. Impermeable - substances as small as helium (He) atoms cannot pass through the hexagonal patterns. Graphene: amazing properties

11. How do we isolate graphene from graphite? + = In CRANN scientists have isolated graphene sheets using soap! Why isolate graphene? What could it be used for? Isolating graphene

12. Electronics devices – used to make transistors and display screens e.g. e-paper, smart phones, transparent loudspeakers. Extremely sensitive sensors for gases and diseases. Stronger, lighter materials, e.g. household products, sports, transport. Invisibility cloaks! Graphene will change the world around us!

13. Apart from graphene, other “layered” materials can be split into single layered “nanosheets”. Offering a whole range of new “super” materials. Can be metallic, semiconducting or insulating, depending on their chemical composition. Uses – added to plastic to make strong materials; supercapacitors, thermoelectric devices. Other “super” materials

14. A form of carbon with a cylindrical nanostructure. Walls consist of one-atom thick sheet of carbon. Discovered in 1991. Carbon nanotubes

15. Nanotubes can be imagined as rolled up sheets of graphene. The graphene sheet can be rolled in 3 different ways to form different types of nanotubes. These subtle differences cause the nanotubes to have different electrical properties. Carbon nanotubes

16. Mechanical - nanotubes have a very high strength to weight ratio; they are at least 100 times stronger than steel but only one sixth as heavy. Electrical - nanotubes in the Armchair configuration conduct electricity very well; nanotubes in the Zigzag and Chiral configuration are semi- conductor materials. Properties of nanotubes

17. Electronics– nanotube transistors for use in computers and phones? Reinforce plastics and concrete structures e.g. aircraft and bridges. Energy– hydrogen fuel cells? Sports industry to create robust, lightweight equipment. Some possible uses of CNTs

18. Could carbon nanotubes be the ideal material for a cable that would extend all the way to outer space because of their high strength to weight ratio? Space elevator - Royal Society Christmas Lecture [12 min YouTube] Space elevator

19. Nanowires e.g. silver could be used in flexible electronic display panels like e-paper. Nanoparticles e.g. zinc, titanium have made suncreams “invisible”. Network of silver nanowires. e-paper. More nanomaterials

20. Nanoelectronics in mobile phones, e- readers, notebooks. In clothing, to repel dirt and water. Cosmetics and sunscreens. In tennis rackets and bicycle frames. Socks – silver nanoparticles to keep your feet cleaner! Coatings on cars and sunglasses to make them anti-misting and scratch- proof. In paints to make them anti-microbial. Nanotechnology is already here!

21. When choosing a material, its properties, performance and cost need to be considered. There are different forms of carbon which differ in the arrangement of carbon atoms at the nanoscale. –Diamond. –Graphite (and graphene). –Carbon nanotubes (CNTs). –Buckyballs. A lot of research is being conducted with graphene and CNTs for their commercial application, particularly in: –Electronics. –Energy- thermo-electrics, supercapacitors. –Reinforcing materials to make them stronger and lighter. Nanomaterials are becoming more common in everyday use. Summary