Lecture 17

Question 1

nitrocellulose

Answer 1

gun cotton, 1845
the first semisynthetic polymer
discovered by Christina Schonbein in Basel, Switzerland in his kitchen

Question 2

Bakelite

Answer 2

1907
first synthetic polymer based on phenol and formaldehyde
discovered by Leo Baekeland
strong and durable
substitute for parts in auto and electric industries

Question 3

history of polymers

Answer 3

polyethylene (1933) –> Polyvinyl chloride (1933) –> Polystyrene (1933) –> Polyamide (1935) –> Teflon (1938) –> Synthetic Rubbers (1942)

Question 4

polyethylene

Answer 4

discovered in 1933
used to insulate radar equipment for airplanes

Question 5

polyamide

Answer 5

discovered in 1935
nylon (wallace carothers at DuPont) to replace silk
used in parachutes

Question 6

teflon

Answer 6

discovered in 1938
used in atomic bombs to isolate hot isotopes of uranium

Question 7

synthetic rubbers

Answer 7

discovered in 1942
1h to synthesize (7 years of natural rubbers)
used for tires and military supplies

Question 8

polymers in pharmaceutical and biomedical products

Answer 8

controlled drug delivery
scaffolds for tissue engineering
oral drug delivery
transdermal patches

Question 9

oral drug delivery types

Answer 9

coating
binders
taste maskers
protective agents

Question 10

polymer

Answer 10

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

Question 11

macromolecules

Answer 11

any large molecule
not necessarily those made of repeating units
polymers are subsets

Question 12

plastics

Answer 12

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

Question 13

natural polymer examples

Answer 13

nucleic acids (DNA,RNA)
proteins (gelatin)
polysaccharides (cellulose, chitosan, alginic acid)

Question 14

synthetic polymer examples

Answer 14

polyethylene
poly(vinyl chloride)
poly(tetrafluoro ethylene) aka teflon
polyurethane
polyacrylate
poly(p-phenylene terephthalamide) aka Kevlar
nylon
silicon rubber
rayon

Question 15

polymer naming

Answer 15

in repeating units
poly(repeating unit)

Question 16

types of structures

Answer 16

homopolymer (all the same)
random copolymer (random insert of different type)
alterante copolymer (every other type)
block copolymer (type 1 then type 2)
graft copolymer (side chain of different type)

Question 17

linear structure

Answer 17

increased
- viscosity
- processability
- solubility

Question 18

cross-linked structure

Answer 18

connected at different points in the polymer
increased
- glass transition temperature
- swellability
- rigidity
- thermal stability

Question 19

condensation polymerization

Answer 19

also known as step polymerization
two or more (bifunctional) monomers carrying different reactive functional groups interact with each other
example - nylon

Question 20

addition polymerization

Answer 20

also known as free-radical polymerization or chain polymerization
stages: initiation (by radical), propagation, and termination (by an inert molecule)
example - polyacrylate, polystyrene

Question 21

types of polymer synthesis

Answer 21

condensation polymerization (small grouping)
addition polymerization (chains)

Question 22

monodispersed

Answer 22

number average (Mn) = weight average (Mw)
polydispersity (Mv/Mn): 1

Question 23

polydispersed

Answer 23

weight average (Mw)&raquo_space; number average (Mn)
polydispersity&raquo_space; 1

Question 24

crystalline

Answer 24

linear polymer
polymer can pack together in regular arrays at T < Tm
manifests a sharp Tm
good barrier to drug diffusion
durable

Question 25

first order (Tm)

Answer 25

specific volume (diagonal, up, diagonal) enthalpy (straight, V, straight)

Question 25

amorphous

Answer 25

more common polymers with irregular structure polymers forms "glass" at T < Tg softens over a wide temperature range (Tg)

Question 26

Glass transition temperature (Tg)

Answer 26

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

Question 27

at T << Tg

Answer 27

polymers are hard, stiff, and glassy

Question 28

at T >> Tg

Answer 28

polymers are rubbery and may flow

Question 29

chewable dosage forms

Answer 29

example - nicotine gum contain a polymer with Tg close to 37 degrees C so that the gum is softened at mouth temperature chew would then release nicotine quickly parking it between cheek and gums slow down nicotine release

Question 30

factors affecting Tg

Answer 30

polymer length side chains crosslinking plasticizers

Question 31

polymer length

Answer 31

the longer, the higher Tg

Question 32

side chains

Answer 32

the bulkier, the higher Tg

Question 33

crosslinking

Answer 33

the more crosslinked, the higher Tg

Question 34

plasticizers

Answer 34

molecules that increase the entropy and mobility of the polymer chains lower Tg when included in polymer products example - water

Question 35

high Tg components

Answer 35

longer polymer length bulkier side chains more crosslinked less plasticizers

Question 36

mechanical properties

Answer 36

stress vs strain slope area under the curve elastic polymers rubbers or elastomers

Question 37

stress vs strain

Answer 37

force/are VS deformation

Question 38

slope

Answer 38

stress/strain : modulus (or stiffness)

Question 39

area under the curve

Answer 39

: toughness

Question 40

elastic polymers

Answer 40

test linear stress vs strain curve up to breaking point deform limitation example - fibers; highly crosslinked polymers

Question 41

rubbers or elastomers

Answer 41

may deform 10 to 15 times their original lengths

Question 42

hydrogels

Answer 42

crosslinked networks of hydrophilic polymers swell rapidly when placed in water retain large volume of water in their structures

Question 43

chemical hydrogels

Answer 43

covalently crosslinked

Question 44

physical hydrogels

Answer 44

crosslinked via hydrogen bonding, hydrophobic interaction, or complexation

Question 45

reason for hydrogels swelling rapidly

Answer 45

chain-water interaction electrostatic repulsion osmotic forces

Question 46

polymers in dosage forms

Answer 46

cellulose-based polymers hydrocolloids water-soluble synthetic polymers water-insoluble synthetic polymers

Question 47

cellulose-based polymer examples

Answer 47

ethylcellulose (tablet coating) carboxymethyl cellulose (superdisintegrant; emulsifier) hydroxpropyl methyl cellulose (tablet binder, coating)

Question 48

hydrocolloids examples

Answer 48

alginic acid (thinking agent in suspension) chitosan (mucoadhesive dosage forms)

Question 49

water-soluble synthetic polymers examples

Answer 49

poly(ethylene glycol) (plasticizer, suppository base, stealth coating) poly(vinyl alcohol) (tablet binder, coating)

Question 50

water-insoluble synthetic polymers examples

Answer 50

poly(lactic-co-glycolic acid) (controlled drug release) polylactic acid (controlled drug release)