Polymerization

Question 1

what are the issues with polymers

Answer 1

pollution from single use plastic

Question 2

what are the features of polymerization rxns

Answer 2

polymers are made by joining small molecules into long chains

starting material affects the reactivity immensely (nonstereogenic or stereogenic)

Question 3

how are polymers prevalent in nature

Answer 3

cellulose in plant cell walls

DNA in double-stranded polymer of nucleotides

Question 4

what does the word polymer mean

Answer 4

it means “of many parts”

Question 5

what does the word plastic mean

Answer 5

it is pliable and easily staped

Question 6

what are some examples of synthetic polymers

Answer 6

polystyrene, nylon, or polyvinyl chloride

Question 7

which polymer is most used worldwide

Answer 7

polyethylene, it is a thermoplastic polymer and is used in packaging

Question 8

describe polymerization

Answer 8

polymerization is a rxn where small molecules are joined together by covalent bonding to form long chain structures

Question 9

what is the degree of polymerization

Answer 9

it is the # of repeating units that characterizes the length of the polymer chain

Question 10

what are the two types of polymerization

Answer 10

-chain reaction/addition polymers that undergo a radical reaction

-step-rxns or condensation reactions

Question 11

what are polymer starting materials made from

Answer 11

petroleum

Question 12

what is BPA

Answer 12

they are phalates/bisphenols that make plastic more flexible/durable and have detrimental health effects

Question 13

what are the solutions to synthetic polymers

Answer 13

create recyclable plastics

bioplastics made from plant crops instead of fossil fuels and are renewable

biodegradable plastics that do not last forever

Question 14

what is lactide

Answer 14

it is made from fermented plant starch and used to make PLA

Question 15

what is L lactide

Answer 15

it is the S,S isomer and better for polymerization

Question 16

what is D,L lactide

Answer 16

it is a racemic mixture of (S,S) and (R,R) isomers, they are worse for polymerization

Question 17

what is the first step in the reaction

Answer 17

the tin catalyst complex will react with the added alcohol, benzyl alcohol

Question 18

how do we stop the reaction

Answer 18

we quench it with acid, which protonates the alcohol and causes it to fall away

Question 19

what are the characteristics of the polymer that results from L Lactide

Answer 19

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

Question 20

what are the characteristics of the polymer that results from D,L lactide

Answer 20

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

Question 21

if the polymer is stereoregular, what appears on the NMR

Answer 21

the methine hydrogen appears as a quartet

Question 22

if the poly is non-stereoregular, what does the NMR look like?

Answer 22

the methine hydrogen peak is much more complex

Question 23

what is percent conversion

Answer 23

it is the ratio of product formed to unreacted starting material

Question 24

what is the purpose of adding HCl at the end of a reaction

Answer 24

it quenches the reaction by protonating the alcohol which causes it to fall away from the catalyst

Question 25

how would the molecular weight of PLA change if you used wet glassware

Answer 25

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

Question 26

what does it mean to be biodegradable

Answer 26

it can degrade in the environment naturally

Question 27

what does it mean to be biorenewable

Answer 27

it can be made from a materially that is a naturally derived source that renews itself

Question 28

what would happen to the polymer synthesis if more catalyst was used in the reaction?

Answer 28

you would have multiple short chains of polymer with the tin catalyst attached

Question 29

what would happen to the polymer synthesis if less catalyst was used in the reaction

Answer 29

you would have larger amounts of unreacted monomer starting material

Question 30

what does it mean if the reaction has a higher percent conversion

Answer 30

it means that more of the monomer was converted to the polymer