29.1 Condensation polymers Flashcards
What is a condensation reaction
Occurs when two molecules react together and a small molecule (usually water) is released.
Eg when esters form, a carboxylic acid and an alcohol react which produces water so this is a condensation reaction
What are some examples of condensation polymers and what are they
- They are usually made from two different monomers each with two functional groups
This means both functional groups can react to form long chain polymers
Eg polyesters, polyamides, polypeptides
What are polyesters made of
A diol and a dicarboxylic acid
So diols have two OH groups and dicarboxylic acids have two COOH groups.
The functional groups at the end of the monomers react to form a chain when molecules of water are released.
What is terylene
A polyester made from benzene-1,3-dicarboxylic acid and ethane-1,2-diol
What is an amide
Formed when a carboxylic acid and an amine react together
Water is produced as OH from carboxylic acid binds with H from amine
Makes an OCNH bond
So C=O then connected to N-H
What is a polyamide
Polyamides have amide linkage OCNH repeated over and over again.
Formed from two different monomers: A di-aminoalkane which has two amino groups reacting with a dicarboxylic acid which has two carboxylic acid groups.
What is Nylon
How can reaction go faster in lab
It is a polyamide called Nylon-6,6 so is formed from…
- 1,6-diaminohexane and hexane-1,6-dicarboxylic acid
Reaction goes faster if a diacid chloride is used rather than dicarboxylic acid.
This makes HCl as a product
What is Kevlar
It is a polyamide
Made from benzene-1,4-diamine and benzene-1,4-dicarboxylic acid
Why is kevlar so strong
- Strength is due to the rigid chains and the ability for the flat aromatic rings to pack together held by strong intermolecular forces.
- Used in bulletproof vests now or anti stab clothing
What type of polymer are polypeptides
They are polyamides and can be made by a single amino acid monomer or many different ones
The amino group of one amino acid reacts with carboxylic acid of another whilst a molecule of water is eliminated.
So OH from carboxylic acid reacts with H from amino part
Why aren’t polyethene and polypropene biodegradable
- They are long chain alkane molecules which are unreactive as they have very strong C-C and C-H bonds which are not polar.
Because remember the C=C bond opens up in addition polymerisation - There is nothing in the natural environment that would break them so they persist for many years
How are polyethene and polypropene disposed off
- In landfill sites along with other rubbish
- They may also be melted down and remoulded
How are poly(alkenes) disposed of
They can be burnt to produce CO2 and water which produces energy.
Poisonous carbon monoxide may be released into atmosphere is combustion is incomplete
However this contributes to problem of CO2 in atmosphere
How are other addition polymers eg polystyrene disposed of
If burnt they may produce toxic products however complete combustion will only produce CO2 and H2O.
Incomplete combustion makes CO and carbon particulates
How are condensation polymers biodegradable
Eg polyesters and polyamides
They can be hydrolysed and are potentially biodegradable by the reverse of the polymerisation reaction by which they were formed
