Exam 2 - Pharmaceutical Polymers

Question 1

Give a general description of a polymer

Answer 1

a large molecule made up of many small repeating units (parts)

Question 2

Define “monomer”, “dimer” & “trimer”

Answer 2

monomer - 1 part
dimer - 2 parts
trimer - 3 parts

Question 3

Define “oligomer”

Answer 3

30-100 parts

Question 4

Define “polymer”

Answer 4

200+ parts

Question 5

Define “macromolecule”

Answer 5

any large molecule (not always made of repeating units)

Question 6

Describe “plastics”

Answer 6

can be molded, cast, extruded, drawn, thermoformed, or laminated into a product

type of polymer

Question 7

List ways that polymers are used in pharma/biomed products

Answer 7

• controlled drug delivery
• scaffolds for tissue engineering
• oral drug delivery:
  coating
  binders
  taste maskers
  protective agents (enteric coating)
  drug carriers preventing crystallization (ASD)
• transdermal patches

Question 8

Give examples of synthetic polymers

Answer 8

• polyethylene, poly(vinyl chloride), poly(tetrafluoroethylene)
• Teflon, polyurethane, polyacrylate, poly(p-phenylene terephthalamide)
• Kevlar, nylon, silicon rubber, rayon

Question 9

Give examples of natural polymers

Answer 9

• nucleic acids (dna, rna)
• proteins (gelatin)
• polysaccharides (cellulose, chitosan, alginic acid)

Question 10

List the different types of polymer topologies

Answer 10

• linear
• branched
• ladder
• hyperbranch
• dendritic
• star
• crosslinked/network

Question 11

Describe “homopolymers”

Answer 11

one type of monomer

rrrrrrrrr

Question 12

Describe “random copolymers”

Answer 12

randomly dispersed polymers

rrrbrbrrbrbbrbrbbrbbrrrbrbrb

Question 13

Describe “alternating copolymers”

Answer 13

polymers are dispersed in a pattern

rbrbrbrbrbrbrbrbrbrb

Question 14

Describe “block copolymers”

Answer 14

sections of polymers are spread out

rrrrrrrrrrbbbbbbbbbb

Question 15

Describe “graft copolymers”

Answer 15

segmented copolymers where one or more polymer chains are covalently bonded to a main polymer chain

rrrrrrrrrrrrrrr
b b
b b
b b

Question 16

Explain the source/monomer based system for naming polymers

Answer 16

• place the prefix poly before the name of the corresponding monomer
• if the monomer name consists of more than one word, or if the name is preceded by a letter or number, the monomer name is enclosed in parentheses
• sometimes the name is based on a hypothetical manner

Question 17

Explain the IUPAC system for naming polymers

Answer 17

1. identify the smallest structural unit
2. assign substituent groups on the backbone of the lowest possible number
3. place the name in parenthesis (or brackets and parentheses) and use the prefix poly
   parentheses are always used following the prefix

the term ethylene is preferred over ethene

Question 18

List examples of polymers named with the source/monomer based system

Answer 18

• poly(arylate)
• poly(methylarylate)
• poly(methyl methacrylate)
• poly(hydroxyethyl methacrylate)
• polyethylene
• poly(vinyl alcohol)

etc…

Question 19

List examples of polymers named with the IUPAC based system

Answer 19

• poly(methylene
• poly(1-hydroxyethane)
• poly(difluoroethylene)
• poly(1-phenylethylene)
• poly(1-carboxylatoethylene)
• poly[1-(1-propyl) ethylene]

Question 20

List the types of polymer synthesis

Answer 20

• condensation synthesis (step polymerization)
• addition polymerization (chain polymerization)

Question 21

Give examples of polymers synthesized via condensation synthesis

Answer 21

nylon

Question 22

Describe condensation synthesis

Answer 22

2+ (bifunctional) monomers carrying different reactive functional groups that interact with each other

Question 23

List the steps of addition polymerization

Answer 23

initiation
propagation
termination

Question 24

Give examples of polymers synthesized via addition polymerization

Answer 24

polyacrylate
polystyrene

Question 26

List the characteristics of linear / less crosslinked polymers

Answer 26

- decreased viscosity - increased processability - increased solubility

Question 27

List the characteristics of less linear / crosslinked polymers

Answer 27

- increased rigidity - increased swelling - increased thermal stability - increased glass transition temperature - more stiff

Question 28

What is "Mn"?

Answer 28

number average

Question 29

What is "Mw"?

Answer 29

weight average larger Mw = less uniform sample

Question 30

Explain the implications of Mw >> Mn

Answer 30

polydispersity >> 1

Question 31

Define "polydispersity"

Answer 31

the distribution of molecular weights within a given polymer sample. it is quantified by the Polydispersity Index (PDI), which is the ratio of the weight-average molecular weight (Mw) to the number-average molecular weight (Mn)

Question 32

Describe the sample if PDI = 1

Answer 32

the sample is monodisperse, meaning all molecules have the same molecular weight

Question 33

Describe the sample if PDI > 1

Answer 33

the sample is polydisperse, meaning there is a distribution of different molecular weights

Question 34

Define "glass transition temperature (Tg)"

Answer 34

the temperature range where a polymer changes from a hard, rigid or “glassy” state to a more pliable, compliant or “rubbery” state

Question 35

Describe a polymer if T >> Tg **(T = temperature)**

Answer 35

polymers are rubbery and may flow

Question 36

Describe a polymer if T << Tg **(T = temperature)**

Answer 36

polymers are hard, stiff, and glassy

Question 37

List factors affecting Tg

Answer 37

- polymer length: the longer the polymer, the higher the Tg - side chains: the bulkier, the higher the Tg - crosslinking: the more crosslinked, the higher the Tg - plasticizers (e.g water)

Question 38

Describe plasticizers, and their effect on Tg

Answer 38

- molecules that increase the entropy and mobility of the polymer chains - lower Tg when included in polymer products (makes more fluid)

Question 39

List features of hydrogels

Answer 39

- crosslinked networks of hydrophilic polymers - swell rapidly when placed in water

Question 40

Explain reasons that hydrogels swell rapidly when placed in water

Answer 40

chain-water interaction electrostatic repulsion osmotic forces

Question 40

Explain the role of ASD (amorphous solid dispersion)

Answer 40

helps solubilize poorly water-soluble drugs by: - dispersing them in a polymer - preventing crystallization - improving dissolution

Question 40

Explain the types of hydrogels and their associated crosslinking

Answer 40

chemical gels (covalently crosslinked) physical gels (crosslinked via hydrogen bonding, hydrophobic interaction, or complexation)

Question 41

Define "stealth polymer"

Answer 41

pecially designed polymers that evade detection by the body's immune system to improve drug stability, reduce immunogenicity, and enhance therapeutic efficacy

Question 42

Give an example of a stealth polymer

Answer 42

pegfilgrastim (PEG) → helps to stabilize protein

Question 43

Explain how ASD contributes to the formulation of ritonavir

Answer 43

- ritonavir is highly insoluble in water - it is co-formulated as an ASD with copovidone (Poly(1-vinylpyrrolidone-co-vinyl acetate)), which enhances solubility and bioavailability