Experiment 26*:
SYNTHESIS AND ANALYSIS OF
COMMERCIAL POLYMERS
Objectives:



To carry out step-wise condensation
polymerizations to prepare a polyamide and
a set of polyesters.
To compare the solubility of various
synthetic and natural polymers in water,
acetone, and toluene.
To determine the length of the polyamide
polymer formed during the synthesis.
Natural vs. Synthetic
Organic Polymers

Proteins


Polysaccharides


hair, skin, tissue
cellulose, starch
Polynucleotides

DNA, RNA




Nylons
Polyesters
Acrylics
Polyvinyls
 Plastic sheeting
and plumbing
materials
 Polystyrenes
 Insulating
materials
Natural Polymers
CH2OH
O
CH2OH
H
OH
CH2OH
O
H
OH
O
O
H
OH
O
O
O
OH
H
OH
O
OH
CH2OH
O
OH
OH
Starch ( (1-4) linkages)
CH2OH
O
RNA
CH2OH
O
CH2OH
CH2OH
O
O
H
OH
O
H
OH
O
H
OH
H
OH
O
OH
OH
OH
OH
O
O
Cellulose ( (1-4) linkages)
Classifications of
Synthetic Polymers

Synthetic polymers are classified by their
method of synthesis.
Synthetic Method
Chain-growth
Addition
polymerization
polystyrenes
Step-growth
Condensation
polymerization
Polyamides
Polyesters
Addition Polymerization
• Two molecules combine to form long chain
polymer.
• Can be linear or branched.
• INITIATION: Initiator adds to C=C of styrene, yields reactive
intermediate.
• PROPAGATION: Reactive intermediate reactions with a second
molecule of styrene, yields another reactive intermediate.
• TERMINATION: Cycle continues until two reactive
intermediates combine to end polymerization.
CH CH2
CH CH2 CH CH2 CH CH2 CH CH2
catalyst
Styrene
polystyrene
Condensation Polymerization—
Polyamides


Two molecules undergo addition accompanied by
the loss of a small molecule as a by product.
Each bond forms independently of others.
H
O
N
H
H
N
Hexamethylene
diamine
+
Cl
Cl
Sebacoyl
chloride
H
diamine
H
H
N
Diacid
chloride
O
N
H
O
H
N
O
O
Cl
N
H
O
n
Nylon 6,10
+ 2 HCl
Condensation Polymerization—
Linear Polyester
O
O
C
C
OH
O
C
+
HO
Ethylene
glycol
Phthalic O
Anhydride
anhydride
O
C
OCH2CH2O
+ 2n H2O
CH3CO2Na
Sodium
acetate
n
linear polyester
diol
Condensation Polymerization—
Cross-Linked Polyester
O
O
C
C
O
C
O
C
+
HO
OH
OH
O
Phthalic
Anhydride
anhydride
OCH2CHCH2O
CH3CO2Na
O
+ H2O
C
Sodium
acetate
O
glycerol
O
C
triol
O
O
C
C
O
OCH2CHCH2O
n
Glyptal resin
Properties of Polymers—
Chain Structures
Linear
Branched
Elastic &
flexible
Cross-linked
Rigid &
Brittle
OVERVIEW




Synthesize polyamide via interfacial
polymerization and determine length of
fiber formed.
Synthesize linear and cross-linked
polyesters.
Compare transparency, elasticity, and
hardness of synthesized polymers to other
provided synthetic and natural polymers.
Compare solubility of natural and synthetic
polymers in various organic solvents.
SYNTHESIS—Nylon 6,10




Pour sebacoyl chloride slowly into a solution
of hexamethylene diamine.
With tweezers, grab the film which forms at
the interface of the two layers and pull up
slowly.
Secure the end of the fiber around a large
test tube and rotate until no more fiber is
produced. KEEP TRACK OF REVOLUTIONS!
Rinse nylon in beaker of tap water, remove
from test tube, and set aside for product
analysis.
SYNTHESIS—Linear and
Cross-Linked Polyesters






Cover watch glasses with foil and label.
Place phthalic anhydride and sodium acetate in
center of watch glass and mix solids with glass
rod.
Add glycerol to one, ethylene glycol to the
other.
Heat and mix with glass rod until mixture
becomes clear and boils.
Remove from heat and cool to RT.
Remove polymer from foil and set aside for
product analysis.
ANALYSIS—
NYLON FIBER LENGTH


Measure the diameter of the test tube
used to collect the nylon fiber.
Determine the length of the fiber
produced using the following formula:
Nylon produced (mm) = (Diameter of test tube) * ( p ) * ( # test tube revolutions)
* Where p = 3.14
Table 26.1:
Nylon Fiber Analysis
Test tube diameter (mm)
# of test tube revolutions
Length of nylon (mm)
ANALYSIS—
SOLUBILITY TESTING





Label 18 small test tubes 1A-F, 2A-F,
and 3A-F.
Measure 3 mL of the appropriate solvent
to the test tubes.
Add a small amount of the polymer as
indicated in Table 26.2.
Shake to mix the contents completely.
Record the solubility of each polymer in
Table 26.2.
ANALYSIS—
SOLUBILITY TESTING
1
A
1
B
1
C
1
D
1
E
1
F
1 = Acetone
A-F = Polymer type
2
A
2
B
2
C
2
D
2
E
2
F
3
A
3
B
3
C
3
D
3
E
3
F
2 = Toluene
A-F = Polymer type
3 = Methanol
A-F = Polymer type
Table 26.2: Physical Property
and Solubility Results
Polymer Type and Solvent
Synthetic
Natural
Solvent
A
Polyamide
B
Linear polyester
C
Cross-linked polyester
D
Polystyrene
E
Starch
F
Cellulose
1
Acetone
2
Toluene
3
Methanol
IMF
Predicted Solubility
1
(circle all
(circle all that
Acetone
that apply)
apply)
(Sol. or
Insol.)
LDF
HBA
LDF
HBA
LDF
HBA
LDF
HBA
LDF
HBA
LDF
HBA
LDF
HBA
LDF
HBA
LDF
DD
HBD
DD
HBD
DD
HBD
DD
HBD
DD
HBD
DD
HBD
DD
HBD
DD
HBD
DD
HBA
HBD
1
2
3
1
2
3
1
2
3
1
2
3
1
2
3
1
2
3
Observed Solubility
2
Toluene
(Sol. or
Insol.)
3
Methanol
(Sol. or
Insol.)
***In the final lab report, copy/paste this table into your
document, and circle the appropriate IMF and solubility
predictions by hand. Observed solubility entries can either be
typewritten or handwritten.***
SAFETY
Sebacoyl chloride,
hexamethylenediamine, and sodium
hydroxide are CORROSIVE!
 Hexane, ethylene glycol, and toluene
are TERATOGENIC!
 Toluene, acetone, hexane, and
methanol are highly FLAMMABLE!

WASTE


All liquid waste generated throughout
the course of the synthesis and
solubility testing can be placed in the
“LIQUID WASTE” container.
Solid polymer waste and aluminum foil
can be placed in the YELLOW SOLID
WASTE CAN at the front of the
room.
CLEANING


All glassware used during this experiment
requires cleaning with SOAP, WATER,
BRUSH followed by a final rinse with
WASH ACETONE.
DO NOT return any glassware to lab
drawer dirty or wet !
IN LAB QUESTION
(The following question should be answered in the laboratory notebook.)


Differentiate between a chain growth
addition reaction and the step growth
condensation reactions used to produce the
polymers described in this experiment.
Give an example of a polymer produced using
each method.
IN LAB QUESTION
(The following question should be answered in the laboratory notebook.)

List the intermolecular forces present in
polystyrene, toluene, and nylon. Explain, in
terms of IMF, why polystyrene is soluble in
toluene, but nylon 6,10 is not.