1
4. Properties of Cationic and Anionic Polymers
A. Polyisobutylene
1. Properties
a. Elastomeric
b. Impervious to air
2. Uses
a. Gaskets and sealants
b. Fuel additive
i. Thickener (reduces unwanted “misting”)
ii. Detergent (keeps fuel injectors clean)
c. Roofing
B. Polyisoprene (rubber)
1. Sources
a. Natural
i. Latex is tapped from tree.
ii. Para rubber tree (hevea brasilensis)
a) Hevea rubber (also natural rubber, NR)
b) Cis-1,4-polyisoprene
c)
Native to Amazon rain forest, now mostly southeast Asia
plantations
iii. Palaquium gutta tree et. al.
a) Gutta percha
b) Trans-1,4-polyisoprene
c) More crystalline than NR.
d) From southeast Asia
iv. Manilkara bidentata tree
a) Gutta balatá
b) Trans-1,4-polyisoprene
c) Almost identical to gutta percha.
d) From South America
2
b. Synthetic
i. Petroleum refining
ii. Cis-isomer is formed
2. Properties
a. Hyperelastic
b. Susceptible to solvent attack
c. Vulcanization creates stronger material.
i. Heated reaction with sulfur to create disulfide crosslinks.
ii. Highly crosslinked polymer forms ebonite.
d. Low Tg (very brittle below Tg)
e. Gutta percha is more crystalline than NR
f. Degree of polymerization and molecular weight lower in gutta percha
than NR.
3. Uses
a. Tires!
b. Rubber bands
c. Latex gloves
d. Adhesives (rubber cement)
e. Chewing gum
f. Erasers
3
C. Polystyrene
6
1. Properties
a. High tensile strength
b. Waterproof
c. Solvent susceptible
d. Non-biodegradeable
e. Highly flammable
f. Bulk polymer is translucent
2. Uses
a. Foam
i. Food packaging
ii. Styrofoam® (Dow)
iii. Pipe insulation
iv. Coolers
b. bulk
i. CD cases
ii. License plate frames
iii. Disposable test tubes
iv. Disposable cutlery
4
D. Polymethylmethacrylate (PMMA)
1. Properties
a. High impact strength
2.
CH 3
H2C
C
b. Transparent (low crystallinity)
C
c. Thermoplastic (easy processing)
O
d. Low cost (compared to polycarbonate)
CH 3
O
Uses
a. Plexiglas® (Rohm and Haas)
b. Hockey glass
c. Bone cement
d. Dentures
CH 3
E. Polyvinylacetate (PVAc)
1. Properties
a. Head to head synthesis
H2C
C
O
b. Water soluble
C
O
c . Ductile
CH 3
d. Susceptibile to degradation from bases
CH 3
e. Precursor to other polymers
i. Hydrolyze to form polyvinyl alcohol (PVA)
2. Uses
a. White glue/carpenter’s glue (w/PVA)
H2C
C
O
H
b. Bookbinder’s glue
c. Coatings
d. Water-soluble packaging (PVA)
5
F. Polyacrylamide (PAA)
1. Properties
a. Water soluble
b. Nontoxic
CH3
H2C
C
C
O
c. Highly water absorbent
NH2
2. Uses
a. Diapers
i. Can absorb up to 300 times its weight in water.
b. Electrophoresis gels
c. Flocculent – additive (usually to water) to cause aggregation of
colloidal particles. Flocculation in a dispersion is analogous to
precipitation in a solution.
d. Thickening agent
e. Soil conditioner – keeps moisture in soil
G. Polyacrylonitrile (PAN)
1. Properties
a. Solvent resistant
CH 3
H2 C
C
b. Engineering plastic
c. Impact resistance
C
N
d. Often used in block co-polymers to improve impact resistance
i. With polystyrene (SAN)
ii. With polystyrene and polybutadiene (ABS)
2. Uses
a. Fibers and clothing
i. Co-polymer with polyvinylacetate to make “acrylic” fiber
ii. Orlon® - DuPont
b. Tents, sails, awnings
c. Fiber reinforcement for concrete
d. Matrix for carbon fiber composite
6
H. Polycaprolactam (Nylon 6)
1. Synthesis
a. Monomer is used to create polymer via ring-opening polymerization
b. Amide linkage breaks at high T and cationic or anionic initiator
c. Nucleophilic attack of nitrogen on carbonyl carbon of lactam.
2. Properties
a. High tensile strength
O
b. Elasticity
C
H2C
N
c. Resistant to abrasion
H2C
d. Resistant to acid and alkali
e. Slightly water absorbent
i. Water absorbing decreases strength
ii. Water acts as placticizer
3. Uses
a. Toothbrush bristles
b. Surgical sutures
c. Fibers, ropes
d. Hosiery
H2C
CH2
CH2
7
I. Polycaprolactone
1. Synthesis
a. Monomer is used to create polymer via ring-opening polymerization
b. Ester linkage hydrolyzes at high T and cationic or anionic initiator
c. Nucleophilic attack of oxygen on carbonyl carbon of lactone
2. Properties
a. Solvent and water resistant
b. Will hydrolyze over time
c. High tensile strength
O
C
H 2C
O
H 2C
CH 2
H 2C
CH 2
3. Uses
a. Shapelock
i. Melts at 160 F (place in warm water, not boiling)
ii. High strength
b. Dental filling
c. Tissue support (for regrowth)
d. Tissue glue
e. Drug capsules