What is a polymer ?
A substance made by joining thousands of small, identical molecules (monomers) in a repeating pattern.
What type of monomer is used in an addition polymer ?
alkene monomers
Why are addition polymers made up of the same atoms as their monomers ?
no other molecules are formed in the addition reaction, so all of the atoms in the monomer end up in the polymer.
Define addition polymerisation.
- an alkene monomer’s carbon to carbon double bond is “opened up” by monomers adding across
- replaces double bond with single bond
- produces addition polymer with “backbone” of carbon atoms
Why are polyesters biodegradable unlike addition polymers ?
microorganisms + bacteria can break down the ester links between molecules
What are the conditions for forming a condensation polymer ?
- at least 2 functional groups present overall
- each monomer to have two of its own functional group
- in the reaction, a small molecule will be formed in addition to the condensation polymer
How is a polyester formed ?
- dicarboxylic acid monomer (COOH functional group) + diol monomer (OH functional group)
- dicarboxylic acid monomer loses OH molecule, diol monomer loses one H atom
- lost atoms form H2O (water) molecule
- another OH and H are lost from either end so that the unit can bond to other repeating units
- dicarboxylic acid monomer + diol monomer –> polyester + 2H2O
Name a polyester.
poly(ethyl ethanoate)
- ethanediol + hexanedioic acid –> poly(ethyl ethanoate) + water
How is a condensation monomer unit represented ?
functional group -[rectangle]- functional group
Describe a practical to make a condensation polymer such as nylon.
- put thin layer of diaminohexane in bottom of beaker
- pour thin layer of decanedioyl dichloride on top
- lift carefully the greyish film that forms and wrap it around a glass rod as a string
- this string is nylon
- HCl gas given off as the small molecule in the reaction
What is a polysaccharide ?
polymer of monosaccharides (sugars like glucose, fructose, sucrose etc.)
include:
- starch
- cellulose
- glycogen
polysaccharides usually lose water as the small molecule during the condensation reaction
What are the 3 atoms used in both mono and polysaccharides ?
- oxygen
- hydrogen
- carbon
What is a polypeptide ?
A polymer made from amino acid monomers. When (multiple) polypeptides are folded up, these are proteins.
What are the two functional groups present in amino acids ?
- amine group (NH2) which is BASIC
- carboxylic acid group (COOH) which is ACIDIC
these two monomers (specifically the OH and H molecules) can react (acid + base) to form water as the small molecule in the condensation reaction.
NOTE: there is also an “R” group on the bottom in the middle connected to the carbon atom which changes depending on which amino acid it is.
What is a nucleotide ?
- monomer used to form DNA (deoxyribonucleic acid)
- forms water as the small molecule in the condensation reaction to form the polynucleotide (DNA)
- 4 different nucleotide monomers
- a nucleotide monomer is the sugar (deoxyribose) bonded to a phosphate group and a base
- ONLY THE BASE CHANGES BETWEEN THESE MONOMERS
- the 4 bases are A, T, C and G
Describe the structure of DNA.
- double helix strands of polynucleotides
- strands held together by intermolecular forces between the base pairs on opposite strands (AT and CG)
