Polymerization Flashcards
what are the issues with polymers
pollution from single use plastic
what are the features of polymerization rxns
polymers are made by joining small molecules into long chains
starting material affects the reactivity immensely (nonstereogenic or stereogenic)
how are polymers prevalent in nature
cellulose in plant cell walls
DNA in double-stranded polymer of nucleotides
what does the word polymer mean
it means “of many parts”
what does the word plastic mean
it is pliable and easily staped
what are some examples of synthetic polymers
polystyrene, nylon, or polyvinyl chloride
which polymer is most used worldwide
polyethylene, it is a thermoplastic polymer and is used in packaging
describe polymerization
polymerization is a rxn where small molecules are joined together by covalent bonding to form long chain structures
what is the degree of polymerization
it is the # of repeating units that characterizes the length of the polymer chain
what are the two types of polymerization
-chain reaction/addition polymers that undergo a radical reaction
-step-rxns or condensation reactions
what are polymer starting materials made from
petroleum
what is BPA
they are phalates/bisphenols that make plastic more flexible/durable and have detrimental health effects
what are the solutions to synthetic polymers
create recyclable plastics
bioplastics made from plant crops instead of fossil fuels and are renewable
biodegradable plastics that do not last forever
what is lactide
it is made from fermented plant starch and used to make PLA
what is L lactide
it is the S,S isomer and better for polymerization
what is D,L lactide
it is a racemic mixture of (S,S) and (R,R) isomers, they are worse for polymerization
what is the first step in the reaction
the tin catalyst complex will react with the added alcohol, benzyl alcohol
how do we stop the reaction
we quench it with acid, which protonates the alcohol and causes it to fall away
what are the characteristics of the polymer that results from L Lactide
it forms a stereoregular polymer that is able to form a well-defined crystalline lattice that is able to pack efficiently. It results in a higher yield and can polymerize better
what are the characteristics of the polymer that results from D,L lactide
it forms a nonstereoregular polymer that does not form a well-defined crystalline lattice and is less efficient at packing. It also does not produce a well-defined crystal and has a lower yield
if the polymer is stereoregular, what appears on the NMR
the methine hydrogen appears as a quartet
if the poly is non-stereoregular, what does the NMR look like?
the methine hydrogen peak is much more complex
what is percent conversion
it is the ratio of product formed to unreacted starting material
what is the purpose of adding HCl at the end of a reaction
it quenches the reaction by protonating the alcohol which causes it to fall away from the catalyst
how would the molecular weight of PLA change if you used wet glassware
it would inhibit the reaction by shifting the equilibrium towards the reactants and by hydrolysis of esters so the overall molecular weight would be less
what does it mean to be biodegradable
it can degrade in the environment naturally
what does it mean to be biorenewable
it can be made from a materially that is a naturally derived source that renews itself
what would happen to the polymer synthesis if more catalyst was used in the reaction?
you would have multiple short chains of polymer with the tin catalyst attached
what would happen to the polymer synthesis if less catalyst was used in the reaction
you would have larger amounts of unreacted monomer starting material
what does it mean if the reaction has a higher percent conversion
it means that more of the monomer was converted to the polymer
