polymers

• condensation polymers

  -reaction where a polymer is produced by repeated condensation between monomers

  -natural con.polymers are all formed by elimination of water

  -can be identified because monomers are linked by ester or amide bonds
• polyester

  -formed between dicarboxylic acid monomers and diol monomers

  -produces by linking these monomers with ester bonds
• formation of polyesters

  -diol and dicarb.acid needed to form polyester

  -when formed, -OH froup on diol and H atom of -COOH are expelled as a water molecule
• polyamides

  polymers where repeating units are bonded together by amide links
• polyamide monomers

  -diamine and dicarboxylic acid are required to form a polyamide

  -diacyl dichlorides can also be used to react with diamine instead of the acid
• amino acids - formation of proteins

  -they are polymers made up of amino acid monomers

  -amino acids have aminocarboxylic acid structure

  -identified by their unique R group

  -dipeptides produced by polymerising 2 amino acids together

  -NH2 and COOH of each amino acid is used to polymerise with another amino acid

  -polypeptides are made through polymerising more than 2 amino acids together
• uses of condensation polymers - thermoplastics

  -polyesters such as terylene is a thermoplastic - repeatedly heated to soften and melt it and cooled to solidify

  -terylene can be shaped to form fine fibres for use in artificial fabrics or moulded into fizzy drinks bottles
• uses of condensation polymers - nylon

  -nylon 6,6 contains diamine and dicarboxylic acid

  -cheap substitute for silk to make roped, twines and velcro

  -often added to natural fibres in clothing and carpets to make them last longer
• uses of condensation polymers - aromatic polyamides

  -nomex and kevlar

  -very tough and lightweight

  -kevlar - bullet proof vests

  -nomex - fireproof suits
• Nylon 6,6

  -synthetic polyamide

  -monomers - 1,6-diaminohexane and 1,6-hexanedioc acid

  -reaction between amine group and carb. acid is slow

  -the dicarboxylic acid is usually first converted to a diacyl dichloride which reacts with diamine much faster
• Kevlar

  -polymer formed through condensation polymerisation

  -polymer chains are neatly arranged with many H bonds between them

  -results in strong, flexible material with fire resistance properties

  -bullet proof vests

  -monomers - 1,4-benzenediamine and 1,4-benzenedicarboxylic acid
• biodegradable polymers

  -both polyesters and polyamides can be broken down using hydrolysis

  -major advantage over polymers produced using alkene monomers

  -When polyesters and polyamides are taken to landfill sites, they can be broken down easily and their products used for other applications
• disposal of polymers: landfill

  ADVANTAGES:

  -buried at specific contained site

  -biodegradable polymers (polyesters and polyamides) will slowly degrade

  DISADVANTAGES:

  -limited land availability

  -slow degradation of plastics

  -leaching of toxic compounds

  -gas emissions
• disposal of polymers: incineration

  ADVANTAGES:

  -less space than landfill

  -energy released from burning can generate electricity

  -prevents build up of polymers in the environment

  DISADVANTAGES:

  -increase in CO2

  -toxic gas emissions and particulates released into atmosphere
• disposal of polymers: recycling

  ADVANTAGES:

  -reuse and conservation of finite hydrocarbon resources

  -reduction of waste going to landfill

  DISADVANTAGES:

  -collection, sorting, separating, remoulding all require energy

  -time consuming

  -expensive