polymers (3.3.12)
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how does the repeating unit of Z-1,2-dichloroethene compare to the repeating unit of E-1,2-dichloroethene?
• the repeating unit is the same • after the C=C bond has broken, there is a single bond formed between the two C atoms, so there is free rotation about the single bond
what feature is required for molecules to be able to form a condensation polymer?
there must be two functional groups on each monomer
reactions between which molecules can form condensation polymers?
• dicarboxylic acids and diols • dicarboxylic acids and diamines • amino acids
in general terms, how do you convert from a monomer structure to a repeating unit structure?
• the carboxylic acid functional group loses -OH • the other functional group (alcohol or amine) loses H • this produces a water molecule, and the remaining atoms join to form the repeating unit
what is an example of a polyester, what monomers is it formed from and what is it used for?
• Terylene • formed from benzene-1,4-dicarboxylic acid and ethane-1,2-diol • used in clothing and tire cords
what are examples of two polyamides, what monomers are they formed from and what are the used for?
nylon-6,6: * formed from hexane-1,6-diamine and hexanedioic acid * used in clothing, carpets, luggage * 6,6 refers to the number of C atoms in each monomer Kevlar: * formed from benzene-1,4-dicarboxylic acid and benzene-1,4-diamine * used in bulletproof vests
what intermolecular forces will be found between polyesters?
van der Waals and permanent dipole-dipole
what intermolecular forces will be found between polyamides?
van der Waals, permanent dipole-dipole and hydrogen bonds
what are the key features of polyalkenes?
they are chemically inert and non-biodegradable
what are the key features of polyesters and polyamides?
they can be broken down by hydrolysis and are biodegradable
how are polyesters hydrolysed?
using hot concentrated sodium hydroxide solution
how are polyamides hydrolysed?
using hot concentrated hydrochloric acid solution
why can polyesters and polyamides be hydrolysed but not polyalkenes?
• the ester or amide groups react with solutions of acid or alkali as they contain polar bonds which attract attacking species like nucleophiles or acids • polyalkenes consist of C-C bonds in the chain which are strong and require lots of energy to break
what are the advantages and disadvantages of disposing of polymers through landfill?
advantages: * more biodegradable plastics could be used to improve rates of decomposition disadvantages: * many landfills are reaching capacity * European regulations mean councils are charged more for using landfill * most polymers are non-biodegradable so take many years to break down
what are the advantages and disadvantages of disposing of polymers through incineration?
advantages: * energy produced from burning rubbish can be used to generate electricity * greatly reduces volume of rubbish * modern incinerators burn more efficiently so most toxins and pollutants can be removed disadvantages: * some toxins may be released * greenhouse gases are emitted
what are the advantages and disadvantages of disposing of polymers through recycling?
advantages: * saves precious resources * saves raw materials as most polymers are formed from compounds which are sourced or produced from crude oil * thermoplastic polymers can be melted down and reshaped disadvantages: * polymers need collecting and sorting which is expensive in terms of energy and manpower * requires careful separation as polymers can only be recycled into the same type