Polymers Exam 3 Flashcards
What is a polymer?
a large molecule that is made up of many small repeating units
What are macromolecules?
Large molecules
Polymers are a subset of macromolecules
What are plastics?
Materials that can be molded, cast, extruded, drawn, thermoformed, or laminated into a product
Focused on the thermal properties
Examples of natural polymers
-nucleic acids (DNA, RNA)
-proteins (gelatin)
-polysaccharides (cellulose, chitosan, alginic acid)
Examples of synthetic polymers
-polyethylene, Teflon, Kevlar, Nylon, silicon rubber, rayon
-anything that starts with “poly”
How to name a polymer
Poly(the repeating unit)
Homopolymer
same polymer all the way through
Random Copolymer
random alternation of two polymers
Alternate Copolymer
two kinds of polymer that alternates in a 1 for 1 pattern
Block Copolymer
When another type of polymer takes up a significant portion of a polymer
Branch Copolymer
when there is a branch containing another polymer
Characteristics of a linear polymer
good viscosity, processability and solubility
Characteristics of a cross-linked polymer
has a GLASS TRANSITION TEMPERATURE
decreased swellability
increased rigidity
less likely to change with thermal stability
Condensation polymerization
“step polymerization”
when two or more monomers that carry different reactive functional groups interact with each other
Addition polymerization
“free radical polymerization”
when radicals recruits monomers and converts it to a radical and so on
Mn
number average
Mw
weight average
Polydispersity
how narrow or broad the weight is distributed
(Mw, Mn)
What does a PD value > 1 mean?
it is BROADLY DISPERSED (not desired)
Glass transition temperature
temperature where the drug changes from “glass” state to a more “rubbery” state
T < Tg
drug is glassy, rigid
T > Tg
drug is pliable
Example that demonstrates glass transition temperature?
nicotine gum
Characteristics of a Crystalline polymer
-linear
-polymer will pack together when T < Tg
-well defined melting temperature
-good for drug diffusion
