16/09/2018 16/09/2018 C2 Material Choices OCR 21st Century W Richards

C2.1 Properties of Materials 16/09/2018 Q. For each of the following materials describe what properties the material needs to have and why…

Properties of materials 16/09/2018 Plastic (polythene) Light Flexible Easily moulded

Properties of materials 16/09/2018 Plastic (polystyrene) Light Rigid Good insulation

Properties of materials 16/09/2018 Nylon Light Tough Waterproof

Properties of materials 16/09/2018 Polyester Light Tough Waterproof

Properties of materials 16/09/2018 Unvulcanised rubbers Low tensile strength Soft Flexible

Properties of materials 16/09/2018 Vulcanised rubbers High tensile strength Hard Flexible

16/09/2018 C2.2 Crude Oil

Using Different Materials 16/09/2018 We use a variety of materials from a variety of different places: Cotton from plants Silk from silkworms Wood and paper from trees These are all “natural” materials – we can also use synthetic (man-made) ones like plastics – these are often made from materials from within the Earth like crude oil.

Chemical formulae 16/09/2018 The chemical formulae of a molecule or compound is simply a way of showing the ratio of atoms in it. For example… Na Cl = sodium chloride (NaCl) K I = potassium iodide (KI) O O = potassium nitrate (KNO3) K N O

Chemical formulae Try drawing these: Water H2O Carbon dioxide CO2 16/09/2018 Try drawing these: Water H2O Carbon dioxide CO2 Calcium sulphate CaSO4 Magnesium hydroxide Mg(OH)2

Simple chemical reactions 16/09/2018 Mg O H Cl Magnesium oxide + Hydrochloric acid Magnesium chloride + Water MgO + 2HCl MgCl2 + H2O Mg O Cu S Magnesium + Copper sulphate Copper + Magnesium sulphate Mg + CuSO4 Cu + MgSO4 Notice that the number of atoms on each side of the equation is the same!

Hydrocarbons and crude oil 16/09/2018 Crude oil is a mixture of HYDROCARBONS (compounds made up of carbon and hydrogen). Some examples: Increasing length C H These different “lengths” are called “_______” and most of them are used as _____. Some are used to make materials such as _______. Longer chains have higher _____ points. Ethane Butane C H Words – boiling, fractions, plastics, fuels

Fractional distillation 16/09/2018 Crude oil can be separated by fractional distillation. The oil is evaporated and the hydrocarbon chains of different lengths condense at different temperatures: Fractions with low boiling points condense at the top Fractions with high boiling points condense at the bottom

Forces between molecules 16/09/2018 Weak force of interaction here Longer molecules = stronger force of attraction, leading to higher boiling points due to the molecules needing more energy to “pull” them away from each other.

Polymers 16/09/2018 C H Ethene Here’s ethene. Ethene is called a MONOMER because it is just one small molecule. We can use ethene to make plastics… Step 1: Break the double bond Step 2: Add the molecules together: This molecule is called POLYETHENE (i.e. polythene), and the process that made it is called POLYMERISATION

16/09/2018 C2.3 Molecular Structure

Uses of addition polymers 16/09/2018 Poly(ethene) Poly(propene) Poly(styrene) Poly(chloroethene), PVC

Words – high, low, strong, weak, stretched, rigid Structure of Plastics 16/09/2018 1) Some plastics have ____ intermolecular forces between each molecule – these have __ melting points and can be ________ easily 2) Some plastics have _____ forces between each molecule. These have ____ melting points and are ____. Words – high, low, strong, weak, stretched, rigid

Forces between molecules 16/09/2018 As we’ve already said, longer molecules have stronger forces of attraction between them. This tends to lead to longer chain plastics being: Stronger Stiffer Harder More difficult to melt (i.e. higher melting point)

Modifying Plastics Polymers can be modified in a number of ways: 16/09/2018 Polymers can be modified in a number of ways: Increasing the chain length ...making it stronger 2) Crosslinking ...making it harder 3) Plasticizing ...making it softer and more flexible 4) Packing more closely (a crystalline polymer) ...making it stronger and more dense

16/09/2018 C2.4 Nanotechnology

Nanotechnology 16/09/2018 Task: To find out what nanotechnology is and what it is used for What is nanotechnology? Define the terms nanoparticle and nanocomposite Gives some examples of its uses Describe some of the future uses of this technology Describe some of the ethical concerns over this technology

Nanotechnology Definition: 16/09/2018 Definition: Nanotechnology is a new branch of science that refers to structures built from a few hundred atoms and are 1-100nm big. They show different properties to the same materials in bulk, partly because they also have a large surface area to volume ratio and their properties could lead to new developments in computers, building materials etc.

How nanoparticles are formed 16/09/2018 Nanoparticles can be formed by a number of methods: They can occur naturally in sea spray They can also be formed during combustion Or they can be formed by grinding down materials

Two examples of nanotechnology 16/09/2018 The “Nano Carbon Pro” tennis racket uses nanoparticles to increase its strength. Silver nanoparticles can be used to give fibres antibacterial properties – look at what they do to e-coli bacteria: Normal e-coli E-coli affected by silver nanoparticles

Nanoscience and health 16/09/2018 Nanoparticles are obviously very small and, as we have said, have a large surface area to volume ratio. This makes them useful but can also make them dangerous. Nanoparticles could easily pass through a cell membrane: I’m going to die… How do these health concerns affect the development of nanotechnology?