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Materials Chemistry

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Students should learn Students should be able to b. Synthetic polymers and plastics

 addition polymerisation

 formation and uses of addition polymers such as

polytetrafluoroethene (PTFE), polymethyl methacrylate (PMMA) and cyanoacrylate (superglue)

 condensation polymerisation

 formation and uses of condensation polymers such as polyesters and polyamides

 polymeric biomaterials such as polylactide (PLA)

 effect of structure on properties such as density, hardness, rigidity, elasticity and biodegradability as exemplified by

i. high density polyethene and low density polyethene ii. nylon and Kevlar

iii. vulcanisation of polymers iv. biodegradable plastics

 plastics fabrication processes

injection moulding, blow moulding, extrusion moulding, vacuum forming and compression moulding

explain the terms “thermoplastics” and

“thermosetting plastics”

describe the characteristics of addition polymers using examples like PTFE, PMMA and

cyanoacrylate

describe the characteristics of condensation polymers: poly(ethylene terephthalate) (PET), nylon, Kevlar and urea-methanal

deduce the type of polymerisation reaction for a given monomer or a pair of monomers

deduce the repeating unit of a polymer obtained from a given monomer or a pair of monomers

write equations for the formation of addition and condensation polymers

state the similarities and differences between addition polymerisation and condensation polymerisation

explain the properties of polymers in terms of their structures

recognise the applications of polymeric biomaterials

describe the process of making biodegradable plastics using PLA as an example

relate the choice of fabrication processes to the properties of plastics and the uses of their products

discuss the importance and problems of recycling plastics

c. Metals and alloys

 metallic crystal structures:

i. close-packed structures as illustrated by hexagonal and cubic close-packed structures ii. open structure as illustrated by

body-centered cubic structure

 unit cells and coordination numbers of metallic structures

 differences in properties between metals and alloys

 describe the close-packed and open structures of metals

 identify the unit cell and determine the

coordination number of a given metallic structure

 recognise that alloys are formed by the introduction of other elements into metals

 explain the differences in properties (e.g. hardness and conductivity) between metals and alloys

 relate the uses of alloys (e.g. steel and brass) to their properties as compared with the pure metals from given information

Students should learn Students should be able to d. Synthetic materials in modern life

 liquid crystals

 nanomaterials

 describe the chemical structures and different phases of organic liquid crystals

 identify the structural features of substances that exhibit liquid-crystalline behaviour

 relate the uses of liquid crystals to their properties

 describe nanomaterials as organic or inorganic materials that have particle sizes up to 100 nm

 state the uses of nanomaterials

e. Green chemistry

 principles of green chemistry

 green chemistry practices

 describe the relation between sustainable development and green chemistry

 understand the green chemistry practices in the production of synthetic materials including the use of less hazardous chemical synthesis and safer solvents and auxiliaries

 evaluate processes for the production of synthetic materials using the principles of green chemistry

Suggested Learning and Teaching Activities

Students are expected to develop the learning outcomes using a variety of learning experiences.

Some related examples are:

 writing chemical equations for the formation of polymers.

 deducing the monomer(s) from the structure of a given polymer.

 performing an experiment to prepare an addition polymer, e.g. polystyrene, Perspex.

 performing an experiment to prepare a condensation polymer, e.g. nylon, urea-methanal.

 searching for information or reading articles on the use of Kevlar in making bullet-proof vests.

 searching for information or reading articles on the advantages and disadvantages of using a biopolymer such as Biopol (polyhydroxybutyrate).

 searching for and presenting information related to structures and properties of polymeric materials that are used as adhesives, semiconductors and drug-carriers.

 searching for information or reading articles on the structural features, properties and uses of Gore-TexTM.

 building models or viewing computer simulations of metallic crystals.

 comparing the appearance, hardness, melting point and corrosion resistance of (a) brass

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 discussing the impact of the development of materials such as polymers or alloys on our society.

 doing a decision-making exercise on selecting the best materials for making items like daily commodities, statues and bridges.

 searching for and presenting information about the properties and structures of memory metals.

 searching for information about the discovery and applications of liquid crystals or nanomaterials.

 building models or viewing computer simulations of nanomaterials.

 performing an experiment to synthesise silver nanoparticles from silver nitrate solution and sodium borohydride solution.

 preparing hexanedioic acid by catalytic oxidation of cyclohexene in the presence of a phase-transfer catalyst (Aliquat 336).

 discussing the advantages and disadvantages of using supercritical carbon dioxide and water as solvents in place of organic solvents in production processes.

 searching for and presenting information related to Ziegler-Natta catalysis on the production of polyethene.

 reading articles or writing essays on the impact of the development of modern materials, such as iron, semiconductors and nanotubes, on daily life.

 searching for uses of nanomaterials, such as in drug delivery, photodynamic therapy, high-definition phosphors, and catalysts.

Values and Attitudes

Students are expected to develop, in particular, the following values and attitudes:

 to appreciate that science and technology provide us with useful products.

 to appreciate the versatility of synthetic materials and the limitations of their uses.

 to appreciate the importance of recycling processes and that material resources are finite.

 to appreciate the need for alternative sources of the compounds presently obtained from the petroleum industry.

 to appreciate the need for considering various properties of a material when it is selected for a particular application.

 to appreciate that close collaboration between chemists, physicists and materials scientists is required for advances in materials chemistry.

 to show concern for the environment and develop a sense of shared responsibility for the sustainable development of our society.

STSE Connections

Students are encouraged to appreciate and comprehend issues which reflect the interconnections of science, technology, society and the environment. Related examples are:

 Synthetic materials can raise our standard of living, but many production processes can have undesirable effects on our health and environment.

 Meeting the requirement of using “green” electronic materials, such as lead-free solder, set by the European Commission posts a challenge to scientists and engineers.

 The safety and toxicity of new materials, such as nanomaterials, should be considered when they are developed and used.

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