Polymers

Question 1

2 Types of Molecular Weight

Answer 1

Number average (Mn)
Weight average (Mw)

Question 2

Number average

Answer 2

Sum of MiNi / Ni

Question 3

Weight average

Answer 3

Sum of Mi^2Ni / MiNi

Question 4

Monodispersed

Answer 4

Mn = Mw

Question 5

Polydispersed

Answer 5

Mw»Mn

Question 6

Polydispersity Index

Answer 6

Mw / Mn

Monodispersed: 1
Polydispersed:»1

Question 7

Crystalline

Answer 7

• linear polymer
• polymer can pack together in regular arrays (T < Tm)
• very sharp Tm (quick melting point) –> single defining melting temp

Advantage: good barrier to drug diffusion & durable

Question 8

Amorphous

Answer 8

• more common
• polymers with very irregular structures
• polymer can form glass at T < Tg
• no single defining melting temp

can be rubber at high temperature and rigid at lower temperature

Question 9

Glass Transition Temperature

Answer 9

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

T«Tg –> polymers are hard, stiff, glassy
T»Tg –> polymers are rubbery and can flow

Question 10

Chewable Dosage Form (nicotine gum)

Answer 10

• polymer with Tg close to 37 degree C so gum is softened at mouth temperature

Question 11

Factors that affect Tg

Answer 11

Polymer Length
- longer, higher Tg

Side Chains
- bulkier, higher Tg

Crosslinking
- more crosslinked, higher Tg

Plasticizer (water)
- molecules that increase entropy and mobility of chains
- lower Tg when included

MOISTURE –> Tg lowers

Question 12

Slope

Answer 12

stress/strain: modulus (stiffness)

Question 13

AUC

Answer 13

toughness

Question 14

Mechanical Properties

Answer 14

Stress: force

Strain: deformation

Question 15

Hydrogel

Answer 15

• network of hydrophilic polymers
• Chemical gel (covalently crosslinked)
• Physical gel (H bond, hydrophobic interaction, complexation crosslinked)
• swells rapidly when in water
• chain water interaction
• electrostatic repulsion
• osmotic force
• retain large volume of water in structures

Question 16

Polymers in Dosage forms

Answer 16

Cellulose Based
- Ethylcellulose (tablet coating)
- carboxymethyl cellulose (superdisintegrant; emulsifier)
- hydroxypropyl methyl cellulose (tablet bind; coating)

Hydrocolloids
- alginic acid (thickening agent)
- chitosan (mucoadhesive)

Water Soluble
- PEG (plasticizer; suppository base; stealth coating)
- Polyvinyl alcohol (tablet binder; coating)

Water Insoluble
- polylactic co glycolic acid (controlled release)
- polylactic acid (controlled release)