Polymers Flashcards
What is an addition polymer?
Made from monomers with C=C bonds which break to connect the monomers
What is a condensation polymer?
Made out of chains of monomers but the monomers have different functional groups which can react and reject a species (usually water)
What is a polyester?
Type of condensation polymer formed from a dicarboxylic acid and a diol
Same reaction that occurs in esterification
What are the uses of some polyesters?
Fabrics
Clothing
Plastic bottles
What are polyamides?
Condensation polymer made from a dicarboxylic acid and diamines
Same condensation reaction occurs to make amides
What is an amide functional group?
H-N-C=O
What is the structure of nylon and what are its uses?
[ -NH-(CH2)6-NHCO-(CH2)4-C=O-]
Fabrics used in textiles
What is the structure of Kevlar and what are it’s uses?
[-NH-aromatic-NHCO-aromatic-C=O-]
Used for bullet and stab proof vests
Why are polyamides so strong?
Due to their ability to form hydrogen bonds
Why is Kevlar so strong?
Kevlar strength is due to the rigid chains and their ability of the flat aromatic rings to pack together held by strong intermolecular forces (hydrogen bonds)
What are polypeptides?
Condensation polymer made from amino acids as their monomers.
Amino acids have a carboxyl group and an amine group and can act as a monomer with themselves to form a polypeptide
What happens during the acid hydrolysis of nylon?
Fast reaction
H+ / H2O
Amino acts as a base and accepts a proton forming a diammonium
What happens during the alkali hydrolysis of nylon?
Slow reaction
NaOH / H2O. (Heated)
Forms a diamine and a carboxylate salt
What happens during the acid hydrolysis of polyesters?
Slow reaction
Strong aqueous acid
Forms a dicarboxylic and a diol
What happens during the alkali hydrolysis of polyesters?
Fast reaction
NaOH / H2O
Forms a carboxylate salt and a diol
Why are addition polymers not biodegradable?
The non polar C=C bonds un reactive and therefore will not break down in the natural environment
They are sent to landfill sites or incinerated
What are the issues with the disposal of addition polymers?
Landfill:
Damage to wildlife
Make leak toxic chemicals into the environment
Incineration:
Burning polyalkenes increases CO2 emissions and therefore contributes to global warming.
Incomplete combustion leads to toxic CO or soot
Other toxic chemicals may be released
How are condensation polymers disposed of?
Undergo hydrolysis
Hey contain polar C=O bonds which are susceptible to attack via nucleophiles
Polyesters and polyamides are potentially biodegradable
What are the advantages and disadvantages of recycling or remoulding polymers?
All polymers can potentially be recycled and melted to be remoulded
Advantages:
Saves diminishing crude oil reserves
Energy input to oil refining not needed
Plastic doesn’t end up in landfill
Disadvantages:
Plastics must be collected sorted and transported which is expensive and requires energy
