Experiment 4

Synthesis of Thermal
Poly(aspartate)- A Green
Polymerization Reaction

Objectives
During this lab, students will:
1. Perform a polymerization synthesis reaction.
2. Use less hazardous chemicals in the polymer synthesis reaction.
3. Calculate the % yield of the polymer.

Introduction
The impact of chemicals on the environment is an issue of increasing global importance. The
need for “green” oil production and drilling chemicals is particularly important. In order to
meet the challenges of increasingly stringent regulations, the chemical industry has begun to
develop production chemical of lower environmental impact.
Thermal polyaspartates (TPA) offer an attractive alternative to conventional oil production
chemicals.
The chemical industry has flourished over the last 150 years, primarily on the manufacturing of
synthetic dyes, pharmaceuticals, and polymers. As much as half of all professional chemists will
work in polymer science to some extent during their career, making this a very broad and
diverse branch of the chemical industry. In fact, synthetic polymers comprise over half of the
compounds produced by the chemical industry.
A polymer is a molecule that is comprised of repeating subunits called monomers. These are
most typically thought of as plastics, but also include proteins such as collagen, keratin,
enzymes, and hormones; polysaccharides such as cellulose, chitin, starch, and glycogen; DNA
and RNA; and materials such as Teflon, rubber, polystyrene, polyester, nylon, and rayon.

Page 1 of 7
CHEM3011 Experiment 4

Polymerization is the chemical conversion of monomers into a polymer chain or network.

Chain-reaction (or addition) polymerization typically involves reactive species such as radicals,
and takes place through three defined steps: initiation, propagation, and termination.
Conversely, step-reaction (or condensation) polymerization proceeds by conventional
functional group transformations, often with the loss of a by-product such as water.
Polymers have proven to be of great use in the petroleum industry where they are used in the
oil recovery process as a scale inhibitor for sparingly soluble alkaline earth salts.
The term scale refers to water-borne mineral deposits and suspended solids that precipitate
from oilfield waters. The accumulation of such mineral scale deposits downhole can reduce oil
production or even block the flow into a production well. These mineral deposits in the surface
facilities also can block normal flow or disrupt the efficiency of the separation and processing of
produced fluids to meet their specified quality requirements.
Scale inhibitors can be applied down hole in a problem production well or in the surface
facilities to delay the onset of these undesirable precipitates. If properly selected, the scale
inhibitor treatment concentrations of only a few ppm into the target stream may be effective to
prevent scale problems.
One of the most widely used scale inhibitors is a polymer called poly(acrylate) (PAC). Although
PAC is relatively non-toxic and environmentally benign, it is not biodegradable.

Thermal poly(aspartate) (TPA) offers an attractive alternative to PAC and other conventional oil
production chemicals. TPA is a highly biodegradable polymer with low toxicity that is just as
effective in preventing scale. It is also an effective dispersant; and has been shown to be an
effective corrosion inhibitor, particularly for CO2-corrosion environments frequently found in
the oil field applications. This makes TPA an ideal greener alternative for use in oil production.
This teaching experiment is similar to the commercial method developed by Donlar Corp.,
which uses no organic solvents and produces little to no waste.
The following principles of green chemistry are employed in the alternative experiment
described herein:
 Prevent Waste

Page 2 of 7
CHEM3011 Experiment 4

 Less Hazardous Chemical Synthesis

 Design Benign Chemicals
 Use of Renewable Feedstocks
 Design for Degradation
 Real-Time Pollution Prevention
 Safer Chemistry for Accident Prevention

Synthesis: This greener reaction involves the polymerization of aspartic acid to create
poly(aspartate), which has similar applications to poly(acrylate) polymers. The synthesis is
conducted in two steps and involves the following two reactions:

L-Aspartic Acid Polysuccinimide

30% α-linkage 70% β-linkage

Polysuccinimide Thermal polyaspartate

Figure 4.1: Green polymerization reaction of TPA

In the first reaction aspartic acid is slowly heated at 250oC and forms the polymer
polysuccinimide (PSI). Polysuccinimide (PSI) is a non-hygroscopic, brownish yellow powder that
is virtually insoluble in water. Its average molecular weight is 10000-20000.
The second step involves the production of TPA by hydrolysis of PSI in sodium hydroxide. The
resulting polymer is a copolymer (it has two repeating monomers). The two monomers are
usually present in a 30:70 ratio.

Page 3 of 7
CHEM3011 Experiment 4

Prelab Questions
Answer the questions on the last page of this document BEFORE the lab session and submit
your answers to your instructor upon entry into the lab. You may print out the last page and
write your answers on the sheet.

Materials

L-Aspartic Acid
Sodium Bicarbonate, saturated solution
1% Hydrochloric Acid
0.1 M Sodium Hydroxide

Procedure
Caution: High temperatures used during heating pose a burn hazard. Glass beakers that are
cooled too quickly can crack from thermal shock. Sodium hydroxide solutions can cause
severe eye and skin damage. Aqueous solutions of hydrochloric acid can be corrosive. Take
all necessary precautions to avoid these hazards and prevent accidents.

Part A: (This part will be completed for you before the lab.)
1. Weigh 1.33 g (0.0100) mol of L-aspartic acid into a 150-mL beaker.
2. Place the beaker into a sand bath (in a 500-mL thermowell) such that the sand covers most
of the bottom half of the outside of the beaker. Use a thermometer to monitor the
temperature of the sand bath, and heat to ~250 °C. Maintain the sand bath at that
temperature until all of the solid has turned to a tan or yellow color or for 2 hours,
whichever comes first. During the period of heating, a glass stirring rod should be used to
agitate the contents of the beaker every minute or so to prevent charring.
3. Allow the beaker to cool to room temperature on a cork ring. Place the cooled solid on a
suction filter and wash with sat. aq. NaHCO3 (3 x 5 mL), water (5 mL), 1% HCl (5 mL), and
water (5 mL).

Page 4 of 7
CHEM3011 Experiment 4

4. Dry the solid in the oven for at least 30 minutes, and then weigh the dried solid. Calculate
the polymer percent yield.

Part B: (This part you will complete during this lab.)

5. Draw 3 tables according to the following instructions given below.
In the first table:
 Write down the polymerization reaction of polyaspartate (TPA), along with the title
of the table.
 Write down the molecular formula, mass, and the molar mass of L-Aspartic Acid.
(The mass of L-Aspartic Acid will be given by your instructor.)
In the second table:
 Write down the first part of the reaction (from L-aspartic acid to PSI), along with the
title of the table.
 Write down the molecular formula of PSI, actual mass of PSI (Instructor), mass of
empty beaker, mass of beaker + PSI, actual weighed mass of PSI (Student),
theoretical mass of PSI, molar mass PSI, and the %yield of PSI.
In the third table:
 Write down the second part of the reaction (from PSI to TPA), along with the title of
the table.
 Write down molecular formula of TPA, molar mass of TPA, the actual mass of TPA,
theoretical mass of TPA, and the %yield of TPA.
6. Weigh a clean dry empty 250 mL beaker on the top-loading balance. Record the value in the
corresponding table.
7. Place 1.00g of solid PSI into a dry, pre-weighed 250-mL beaker. Add 100 mL of 0.1 M
aqueous NaOH to the beaker of polysuccinimide.
8. Stir the mixture until all of the solid dissolves. You might need to warm the contents of the
beaker. Place the beaker on a hot plate, and bring the solution to a boil. Use extreme
caution. Use a glass stirring rod to break up surface tension (rather than a magnetic stir bar
or boiling chips). Continue heating until the water has almost completely evaporated.
[Note: If the contents of the beaker start to splatter, remove the beaker from the hot
plate.]
9. Using the hot hands rubber, remove the beaker from the hot plate, and allow it to cool on
the bench for 5 minutes.

Page 5 of 7
CHEM3011 Experiment 4

10. Carefully hold the beaker using the hot hands rubber and place it in the oven for at least 30
minutes to complete the drying.
11. Carefully remove the beaker from the oven using the hot hands rubber and let it cool down
on the bench.
12. Weigh the dried solid and record the value in the corresponding table.

Questions
1. Using Figure 4.1, determine the molecular formula and the molar mass of the following:
a) L-Aspartic Acid
b) Polysuccinimide (PSI)
c) Thermal Polyaspartate
Note: Write down the molecular formulas and record the values of the molar masses
in the assigned block of each table.
2. Calculate the percent yield of the polysuccinimide, PSI, using the data provided from
Part A of the experiment. Record it in the designated table.
3. Calculate the polymer percent yield of your sodium poly(aspartate). Record the value in
the assigned table.
4. Comment on the %yield of the polymer (TPA) and explain why the % yield could be
higher than 100%.

References
A Guide to Green Chemistry Experiments for Undergraduate Organic Chemistry Labs; Beyond
Benign, and My Green Lab:
https://www.mygreenlab.org/uploads/2/1/9/4/21945752/a_guide_to_green_chemistry_experi
ments_for_undergraduate_organic_chemistry_labs_march_2018_v2.pdf
Oil Field Chemicals, 7th international symposium; Biodegradable Multifunctional Oil Production
Chemicals: Thermal Polyaspartates: https://www.osti.gov/etdeweb/servlets/purl/491906

Page 6 of 7
CHEM3011 Experiment 4

Pre-Lab Assignment 4
Synthesis of Thermal
Poly(aspartate)- A Green
Polymerization Reaction

STUDENT NAME Grade:

❑ =¿
4
STUDENT ID

Answer the following questions BEFORE the lab session and submit to your
instructor upon entry into the lab.

1. What are TPAs used for in the petroleum industry?

2. Why TPA is considered a “green” alternative to PAC?

Page 7 of 7