Synthesis of a Crosslinked Epoxy Resin Medallion in the Organic Chemistry Laboratory

Katherine W Stickney,John T Wyeth,Joe C Burnell

doi:10.12691/wjce-7-4-1

Katherine W Stickney, John T Wyeth + Show 1 more

Open Access

https://doi.org/10.12691/wjce-7-4-1

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Abstract

Polymer synthesis has a limited inclusion in most organic chemistry lecture curricula, so emphasizing the concepts of polymer chemistry in a laboratory setting gives students hands-on experience in new content and broadens the scope of the class. The details and outcomes of a robust and well-developed laboratory procedure for the synthesis of a crosslinked epoxy network polymer are described. This experiment has been a part of a first-semester, introductory undergraduate organic chemistry laboratory curriculum for more than two decades and has positively impacted over eight hundred students. The experiment had the unique aspect that students cured the resin in a round, seven-centimeter mold, forming a hardened epoxy disk. This disk, or medallion, was decorated in two different ways: first, a design was etched into the mold before curing to form a permanent imprint; second, the final epoxy medallion was decorated, post-cure, with colored permanent markers and glitter glue. After this laboratory experiment, students took home a durable ornament as a memento of their first-semester organic chemistry laboratory course.

Highlights

Polymer chemistry is rarely introduced in K-12 science classes [1,2] aside from a discussion of plastics and recycling
Polymer synthesis may garner a brief mention in an undergraduate organic chemistry course, in the context of polymerization reactions of alkenes, but polymeric materials are often overlooked in the undergraduate chemistry curriculum as a whole [3,4,5]
Since polymer chemistry is one of the largest sectors in the chemical industry workforce [7], addition of an undergraduate experience in polymer synthesis would benefit any student who may be seeking employment after graduation [8,9]. This gap in the curriculum was addressed by conducting a polymer synthesis laboratory near the end of the first-semester organic chemistry laboratory course

Summary

Introduction

The synthesis of an epoxy network using an aromatic amine, 4,4’-diaminodiphenyl sulfone (or 4-aminophenyl sulfone), and a diepoxide (the diglycidyl ether of bisphenol A, or DGEBA) is described here This procedure yields a high temperature epoxy material, molded into the shape of a medallion, and provides a durable plastic ornament that can be taken home by the students. The best mold for the epoxy was found to be a heavy-weight aluminum weigh dish which had two benefits: first, an image can be inscribed into the bottom of the dish (this image will be permanently imbedded into the polymer surface); second, the heavy-gauge dish can be completely removed/peeled away from the polymer with the help of pliers, leaving a clean and smooth surface The chemistry of this lab is quite robust and reproducible and yields consistent results year after year. Note that the secondary dish can be recycled from year to year

Overview of the Polymer Lab

Overview of the Synthesis of the High Temperature Epoxy Resin

Materials and Procedure

Pedagogical Goals of the Epoxy Synthesis Reaction

Conclusion

Student Handout