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Polymerization of Nylon

Grades: 9-12
Author: Dr. Carin A. Helfer
Source: Teegarden, D. (2004). Interfacial Step-Growth Polymerization: Synthesis of Nylon. Polymer Chemistry: Introduction to an Indispensable Science (pp. 228-230). Arlington: NSTA Press.


Abstract

In this lesson, students will combine two monomers to make nylon 6,6, which is a polymer.


Objectives

What should students know as a result of this lesson?

  • Students will know basic polymer terminology.
  • Students will know what a step-growth polymerization is.
  • Students will understand interfacial polymerization.

What should the students be able to do as a result of this lesson?

  • Students will be able to perform a chemical reaction in the lab.
  • Students will describe step-growth polymerization.

Materials

  • Mystery Nylon Factory from Flinn Scientific Inc. that contains the following:
    • Hexamethylenediamine/sodium hydroxide solution
    • Adipoyl chloride/hexane solution
  • Small beakers or glass jars, the size of beaker will depend on whether small groups of students will perform the experiment or if a classroom demonstration is performed.
  • Forceps
  • Stirring rod
  • Larger glass container for washing the nylon
  • Glass graduated cylinder
  • Chemical safety goggles
  • Chemical-resistant gloves
  • Laboratory apron
  • Fume hood or well-ventilated area

* This lesson requires potentially hazardous materials. Please review the Material Safety Data Sheets for the reactants and products carefully before attempting this lesson.


Procedures

Engagement

Prior training in chemistry is necessary before attempting this lesson plan. The experiment can be potentially dangerous and could result in injury. The lesson must be conducted at one's own risk. Please review the Material Safety Data Sheets for the reactants and products carefully before attempting this lesson.

The students should have a basic understanding of polymers before attempting this lesson. A multimedia presentation that introduces the concept of polymers can be found at the AGPA website: http://www.agpa.uakron.edu/p16/what-are-polymers.php

As an introduction to polymerization and to engage the students, show the video below of a Polymer Science graduate student performing a polymerization in a laboratory hood.


After seeing the polymerization, tell the students that they will perform a polymerization for themselves or watch a demonstration of a polymerization in their classroom.

Assessment: Through a discussion on polymers, determine that the students have a basic understanding of polymeric materials before starting the Exploration.

Exploration

This lesson can be done as a demonstration for the whole class or with the students in small groups. The following procedure is appropriate for small groups. Scale-up as necessary for a classroom demonstration. While handling the chemicals, wear chemical-resistant gloves, safety goggles, and a laboratory apron.

Pour 5 mL of the hexamethylenediamine/sodium hydroxide solution into a small glass beaker. Carefully add 5 mL of the adipoyl chloride/hexane solution to the beaker attempting to not mix the two layers. This can be accomplished by tilting the beaker slightly and pouring the solution down the side of the beaker.

At the interface, the reaction occurs with one of the products being nylon. Use forceps to pull the nylon from the interface and wind the polymer around the stirring rod. Continue to wind the polymer onto the stirring rod. When all of the nylon (or a sufficient amount) has been collected, put the polymer into the large glass container of water to wash. Leave the polymer in the water overnight, remove it, and then allow the polymer to dry. When the nylon is odor-free, it is safe to handle without gloves.

Dispose of any leftover reagents by stirring together to allow them to fully react. Transfer any unreacted liquid into a hazardous waste container for proper disposal. The solid nylon that has been washed and dried can be disposed of in the trash.

Assessment: Monitor the students' lab work to ensure that safe lab procedures are being followed.

Explanation

Polymers are very large molecules that are made by combining smaller molecules, called monomers, together. In this experiment, a step-growth polymerization occurs at the interface of the two monomers. The monomers are each dissolved in a solvent. However, neither monomer is soluble in the solvent of the other monomer.

The reaction that occurs is as follows:

Polymerization of Nylone Lesson

Ask the students to describe the properties of the nylon produced. Some additional questions that can be discussed are as follows:

  1. Why is the nylon formed at the interface? (The two solutions are not miscible so the reaction can only occur at the interface.)
  2. What conclusions can you make about the solubility of adipoyl chloride, hexamethylene diamine, and nylon 6,6? (Neither reagent is soluble in the other's solvent. The nylon 6,6 is not soluble in either solvent.)

Assessment: Monitor that the students understood the polymerization of nylon.

Elaboration

The number of natural (occurring in nature) and synthetic (man-made) polymers is extremely large. Have the students identify a polymer of interest and research this material. The instructor can decide if the students should write a report, create a presentation, or both, for the student's chosen polymer.

Assessment: Create a rubric to grade the report and/or presentation.


Prerequisites

The instructor must have training in chemistry and chemistry lab before attempting to allow students to perform this reaction.

The students need to have basic chemistry knowledge and basic polymer knowledge.


Best Teaching Practices

  • Inquiry Approaches

Alignment with Standards

NGSS Standards:

  • HS-PS1-2 Construct and revise an explanation for the outcome of a simple chemical reaction based on the outermost electron states of atoms, trends in the periodic table,and knowledge of the patterns of chemical properties.
  • HS-PS2-6 Communicate scientific and technical information about why the molecular-level structure is important in the functioning of designed materials.
  • HS-LS1-6 Construct and revise an explanation based on evidence for how carbon, hydrogen, and oxygen from sugar molecules may combine with other elements to form amino acids and/or other large carbon-based molecules.

Common Core Standards:

  • RST.9-10.3 Follow precisely a complex multi-step procedure when carrying out experiments, taking measurements, or performing technical tasks, attending to special cases or exceptions defined in the text.
  • WHST.9-10.2 Write informative/explanatory texts, including narration of historical events, scientific procedures/experiments, or technical processes.

National Standards:

  • 9-12 Physical Science

Ohio Standards:

  • 9-12 Physical Science

Content Knowledge

Step-growth polymerization was originally called condensation polymerization according to W. H. Carothers. In condensation polymerization, a small molecule is lost during the reaction. In the polymerization in this experiment, HCl is the small molecule that is formed in addition to the polymer (nylon). P. J. Flory modified the original classification of Carothers to emphasize the mechanism of the polymerization. The other type of polymerization is known as addition polymerization. In addition polymerization, the loss of a small molecule does not occur during the reaction.

The Macrogalleria website created by the Department of Polymer Science at The University of Southern Mississippi has additional details on nylons at: http://pslc.ws/macrogcss/nylon.html

Billmeyer, Jr., F. W. (1984). Textbook of Polymer Science (pp. 25-26). New York: John Wiley & Sons, Inc.


Safety

Hexamethylenediamine/sodium hydroxide solution is toxic if ingested and is corrosive.

Adipoyl chloride/hexane solution, a flammable liquid, is toxic if ingested or inhaled.

Work in a fume hood or in a well-ventilated room to avoid breathing any vapors.

Avoid skin contact by wearing a chemical-resistant apron, chemical-resistant gloves, and chemical safety goggles.

Do not handle the nylon material without chemical-resistant gloves until the polymer has been thoroughly washed.


Applications

Polymers are considered a modern material because man-made polymers have only been in existence since the mid-1800's. Today, many scientists/engineers around the world are working on creating new polymers to meet the specific needs for better physical properties. Through chemistry, structure, and processing, a wide variety of final properties can be produced.


Assessment

Assessments are completed during each step of the Learning Cycle.


Other Considerations

Grouping Suggestions: If this lesson is not done as a demonstration, it can be performed in groups of 3-4 students.

Pacing/Suggested Time: Two 40-minute class periods will be necessary for the Engagement, Exploration, and Explanation steps. The Elaboration will take additional class periods with the time depending on the Elaboration.


Printable PDF Worksheets

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