C.11. Polymers

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  • Created by: sana.aaa
  • Created on: 30-01-18 16:44

Addition Polymerisation

  • the fractional distillation of crude oil and cracking in an oil refinery produces a large range of hydrocarbons
  • hydrocarbons are the main fuels used to power vehicles
  • plastics that are used every day are made up of huge molecules made from lots of small molecules joined together- these small molecules are called MONOMERS
  • the huge molecules they make are called POLYMERS
  • ethene ---> poly(ethene)
  • ethene is the smallest unsaturated hydrocarbon molecule, it can be used to make a polymer known as poly(ethene)
  • POLY(ETHENE) is a really useful plastic as it is STRONG and EASY TO SHAPE. it is TRANSPARENT, except when a colouring material is added to it
  • plastic carrier bags, some drink bottles, dustbins, washing-up bowls, and cling film are examples of the uses of POLY(ETHENE)
  • poly(propene) forms a very STRONG, TOUGH PLASTIC- made into carpets, milk crates, and ropes
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Addition Polymerisation 2

  • when alkene molecules join together, the double covalent bond between 2 carbon atoms in each molecule "opens up"- it is replaced by a single carbon-carbon covalent bond between the 2 carbon atoms
  • the polymer chains they form are made up of a "backbone" of thousands of carbon atoms- this type of ADDITION POLYMERISATION and the polymer formed is known as an addition polymer
  • the long chains molecules in polymers are made up of repeated patterns of atoms. in poly(ethene), the repeating unit of the polymer has the same displayed formula as one of its monomers, but the C=C double bond in the monomer is changed to a single bond, with a single bond sticking out at each end
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Condensation polymerisation

  • as well as addition polymerisation, in which the monomers all contain a C=C, chemists can also make polymers from another type of reaction- this is called CONDENSATION POLYmerisation
  • in addition polymerisation, there is only one product formed in this reaction, the polymer, whereas in condensation polymerisation there are 2 different products
  • the main product is the polymer, but you usually also get a small molecule given off
  • the small molecule is most commonly either water H2O or hydrogen chloride, HCl
  • addition polymerisation---> the addition polymer
  • condensation polymerisation ---> the condensation polymer + a small molecule
  • in the plastics industry, the monomers used for addition polymerisation are often all the same alkene
  • in condensation polymerisation, there are 2 different monomers used
  • one monomer will have a certain functional group at both ends of its molecule
  • the functional groups on the 2 different monomers must react together
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Polyester

  • an ester is made up of an ALCOHOL (with the -OH functional group) and a CARBOXYLIC ACID (with the -COOH functional group) react together to give an ester + water
  • so to make a POLYESTER chain, you would start with one ALCOHOL monomer with an -OH group at each end, and another CARBOXYLIC ACID with a -COOH group at each end
  • the monomers link together as they polymerise by "ester links", and a water molecule is given off as each link is made in the reaction:

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Polyester 2

  • a diol + a dicarboxylic acid---> a polyester  + water
  • polyesters are formed from the condensation polymerisation of diol and a dicarboxylic, with h2o, given off in the reaction
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Natural polymers

  • carbohydrates are compounds are made up of molecules containing carbon, hydrogen, and oxygen atoms- they have a general formula of:
  • and are made up of one or more types of sugar molecules
  • the most commonly known sugar is the glucose, c6h12o6, made during photosynthesis in plants
  • glucose is called a MONOSACCHARIDE (made of one sugar unit), as is another sugar, fructose, a low-calorie alternative to glucose used to sweeten food
  • glucose molecules are made up of a six-membered ring structure, fructose has five-membered rings
  • monosaccharides can bond together to make larger molecules
  • sucrose is made from a glucose and fructose molecules bonded together- via the condensation reaction in which h2o is lost when making the link
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Natural polymers 2

  • the monosaccharide sugars can also act as the monomers to make polymers, called POLYSACCHARIDES - they can be made up of thousands of sugar monomers
  • Glucose monomers---> starch polymers+water
  • glucose monomers---> cellulose polymers + water
  • plants use starch they make from glucose as energy stores, and the cellulose they make is used to give the plant its structures
  • proteins are also natural polymers
  • variety of amino acid monomers---> protein polymers +water
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Polypeptides and proteins

  • the monomers of proteins are called amino acids
  • the amino acids have 2 functional groups, one basic(the amine group -NH2) and one acidic (the carboxylic acid group, -COOH). the simplest amino acid is called GLYCINE
  • acids and bases react together, so with amino acids, you have potential monomers with reactive groups at each end
  • 20 different amino acids that join together (polymerise) in a great variety of sequences to make more than 10 000 proteins in your body
  • each of the different amino acid monomers is given a three-letter abbreviation when listing their sequence in a protein
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Nucleotide monomers of DNA

  • DNA enables living things to develop and function
  • DNA's structure contains a genetic code that determines the different amino acid sequences of every protein in your body
  • the genetic code can be copied to make protein molecules with exactly the same sequence of amino acids
  • DNA is made by the condensation polymerisation of repeating units of monomers called NUCLEOTIDES
  • DNA is known as a POLYnucleotide
  • millions of nucleotides----> DNA (a polynucleotide) + water
  • the DNA molecules consist of a double helix made up of 2 long polymer strands of nucleotides. the 2 strands run in opposite directions to each other- they are held in place by the intermolecular forces down the length of each polymer strand
  • there are 4 different nucleotide monomers that can react with each other to DNA polymers
  • a nucleotide consists of a sugar-phosphate backbone, with a monomer attached to it
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