Chapter 16 Polymerization Flashcards
1
Q
Formation of Polyesters
A
-
Addition polymerisation has been covered in reactions of alkenes
- They are made using monomers that have C-C double bonds joined together to form polymers such as (poly)ethene
-
Condensation polymerisation is another type of reaction and is used in the making of polyesters
- A small molecule (eg. a water molecule) is lost when the monomers join together to form a polyester
- Polyesters contain ester linkages
2
Q
This polymer structure shows an ester functional group linking monomers together
A
3
Q
Formation of polyesters
A
-
A diol and a dicarboxylic acid are required to form a polyester
- A diol contains 2 -OH groups
- A dicarboxylic acid contains 2 COOH groups
- When the polyester is formed, one of the -OH groups on the diol and the hydrogen atom of the -COOH are expelled as a water molecule (H2O)
4
Q
Expulsion of a water molecule in this condensation polymerisation forms the polyester called Terylene (PET)
A
5
Q
Hydroxycarboxylic acids
A
- A single monomer containing both of the key functional groups can also be used for making polyesters
- These monomers are called hydroxycarboxylic acids
- They contain an alcohol group (-OH) at one end of the molecule while the other end is capped by a carboxylic acid group (-COOH)
6
Q
Both functional groups are needed to make a polyester are from the same monomer
A
7
Q
Amide link
A
- Polyamides are also formed using condensation polymerisation
8
Q
what are required to form a polyamide
A
- A diamine and a dicarboxylic acid
- A diamine contains 2 -NH2 groups
- A dicarboxylic acid contains 2 -COOH groups
- Dioyl dichlorides can also used to react with the diamine instead of the acid
- A dioyl chloride contains 2 -COCl groups
- This is a more reactive monomer than dicarboxylic acid. However, a more expensive alternative
9
Q
The monomers for making polyamides (diagram)
A
10
Q
Nylon 6,6 is a
A
- synthetic polyamide
- Its monomers are 1,6-diaminohexane and hexane-1,6-dioic acid
- The ‘6,6’ part of its name arises from the 6 carbon atoms in each of Nylon 6,6 monomers
11
Q
Nylon 6,6 is a
A
- synthetic polyamide
- Its monomers are 1,6-diaminohexane and hexane-1,6-dioic acid
- The ‘6,6’ part of its name arises from the 6 carbon atoms in each of Nylon 6,6 monomers
12
Q
Kevlar
A
- The polymer chains are neatly arranged with many hydrogen bonds between them
- This results in a strong and flexible polymer material with fire resistance properties
- These properties also lend Kevlar to a vital application in bullet-proof vests
- The monomers used to make Kevlar
- 1,4-diaminobenzene
- Benzene-1,4-dicarboxylic acid
13
Q
Kevlar is made using a diamine and dicarboxylic acid monomers(diagram)
A
14
Q
Aminocarboxylic acids
A
- Molecules like this are called amino carboxylic acids
- They are able to polymerise to form a structure similar to Nylon 6,6
- They are able provides both of the function groups necessary for an amide/peptide link
15
Q
6-aminohexanoic acid can be polymerised to make the synthetic polymer Nylon 6,6
A
16
Q
Protein hydrolysis
A
- Proteins (polypeptides) can be broken down into its constituent amino acids
- This process occurs through a hydrolysis reaction
17
Q
Making Proteins
A
- Proteins are vital biological molecules with varying functions within the body
- They are essentially polymers made up of amino acid monomers
- Amino acids have an aminocarboxylic acid structure
- Their properties are governed by a branching side group - the R group
18
Q
Different amino acids are identified by
A
- their unique R group
- The names of each amino acid is given using 3 letters
- For example Glutamine is known as ‘Gln’
- Dipeptides can be produced by polymerising 2 amino acids together
- The amine group (-NH2) and acid group (-COOH) of each amino acid is used to polymerise with another amino acid
19
Q
- Polypeptides are made through polymerising more than 2 amino acids together (diagram)
A
20
Q
Deducing the Repeat Unit of a Condensation Polymer
A
- In condensation polymerisation the monomers either contain 2 of the same functional group or one single monomer has both functional groups needed for polymerisation
- For example Diamine and dicarboxylic acid
- Or an aminocarboxylic acid
- When presented with 2 monomers there are steps to take in order to deduce the repeat unit of a condensation polymer
21
Q
Identifying Monomers in Condensation Polymers
A
- When a section of polymer is presented, the monomers can be identified by considering the small molecules expelled from the monomers
- If a water molecule is expelled, the -OH must have been from an acid group
- The hydrogen atom may be from an amine group of a monomer.
- If the molecule was hydrochloric acid (HCl), a dioyl chloride monomer may have been used
22
Q
Predicting Type of Polymerisation
A
- When a set of monomers are given in an exam question, the type of polymerisation can be determined
- Firstly, it’s important to identify the key functional groups in the monomers
23
Q
Addition polymerisation
A
- If the monomer/s contain a C=C double bond, they will polymerise through addition polymerisation
- The double bond can open up in order to add more monomers either side of the starting monomer
- This type of polymerisation makes (poly)alkenes
23
Q
Addition polymerisation
A
- If the monomer/s contain a C=C double bond, they will polymerise through addition polymerisation
- The double bond can open up in order to add more monomers either side of the starting monomer
- This type of polymerisation makes (poly)alkenes
24
Q
(Poly)alkenes can be produced if there are
A
- 2 or more alkene monomers as well
- When more than one monomer is used for addition polymerisation, the resulting product is known as a copolymer
25
Q
Monomers for condensation polymers table
A
26
Q
Identifying addition polymerisation
A
- The polymer backbone of an addition polymer does not contain functional groups
- The backbone of the polymer is generally a chain of carbon atoms
- There may be sidechains branching off from the backbone
- Some examples of side chains are benzene rings, nitrile groups (-CN) and halogen atoms (-F/-Cl/-Br/-I)
27
Q
Identifying condensation polymerisation
A
- A condensation polymer can be identified by functional groups on the polymer backbone
- Polyesters contain ester links and polyamides contain amide/peptide link on the backbone itself
28
Q
Hydrolysis of polyesters
A
- Ester linkages can also be degraded through hydrolysis reactions
- Acid hydrolysis forms the alcohols and carboxylic acids that were used to form the polyesters
29
Q
Biodegradable polymers
A
- Both polyesters and polyamides can be broken down using hydrolysis reactions
- This is a major advantage over the polymers produced using alkene monomers (polyalkenes)
- When polyesters and polyamides are taken to landfill sites, they can be broken down easily and their products used for other applications
30
Q
Hydrolysis of polyamides (acidic hydrolysis)
A
- In acidic hydrolysis, acid (such as hydrochloric acid) acts as the catalyst
- Polyamides are heated with dilute acid
- This reaction breaks the polyamide into carboxylic acid molecules and ammonium chloride ions
31
Q
Hydrolysis of polyamides(Alkaline hydrolysis)
A
- The polyamide is heated with a species containing hydroxide ions (eg. sodium hydroxide)
- This breaks the polymer into the sodium salts of its monomers (dicarboxylic acids and diamines)
- If the poly amide link used an aminocarboxylic acid as the monomer, then a sodium salt of the original amino acid is reformed
32
Q
When polyamides are degraded by hydrolysis, carboxylic acids and amines are formed
A
33
Q
Disadvantages of photo degradability
A
- Despite this ability being a great advantage of polyesters and polyamides, it may pose a problems when the polymers are repurposed
- When applied to a new use, the biodegradability could give a weaker polymer
- Breaking down polymers also poses another challenge
- Once used, polymeric materials are taken to landfill sites where many other materials are piled on top of each other
- This could mean that photodegradable polyesters or polyamides do not have access to UV light in order to break down naturally
34
Q
Photodegradation of Polymers
A
- Polyesters and polyamides are biodegradable polymers for a number of reasons
- One such reason is their ability to breakdown with the use of light
- Carbonyl groups (C=O) along polymer chains are able to absorb energy from the Electromagnetic Spectrum
- In particular Ultraviolet (UV) light
- Absorbing UV light weakens the carbonyl areas of polymers and breaks them down into smaller molecules
35
Q
Recycling plants can burn used
A
plastic materials
- The energy released from burning can be used to generate electricity
- Burning plastics in oxygen releases carbon dioxide and water (complete combustion) which can contribute to global warming
36
Q
- Many of the polymers in use have been produced through addition polymerisation of alkenes
A
- The (poly)alkene chains are non-polar and saturated
- This makes them chemically inert and therefore non-biodegradable
- (poly)alkenes can be melted and recycled into new uses
- However, even in the new applications, the (poly)alkenes are not biodegradable
