Every time I come across a new polymer microwave synthetic route I have to think of all the gooey mess that I have made in many of my reactions. Maybe I have been a polymer chemist for a lot longer than I imagined. Many of the traditional concepts we learn as synthetic chemists apply across all of the disciplines, but polymer chemists have to deal with additional complications that are not often the part of the curriculum. The added viscocity and quasicrystalline nature provide the interest — just look at all of the special properties, but it also makes it more challenging.

Microwave approaches for polymer methods is relatively new. Early examples in kitchen microwaves showed moderate success — and certainly a lack of control for a structured development…..making it difficult to repeat and gain insights for progressing the field of study. With the success of commercial microwaves for the lab, this has changed dramatically……to the point now where we witness 100s of microwave polymer publications each year. Several reviews will bring you up-to-date on the current state of research: Wiesbrook Hoogenboom and Schubert 2004  Hoogenboom and Schubert 2007 and Bogdal 2007

There are three main categories that are usually talked about: Step Growth Polymerization, Ring-Opening Polymerization and Free Radical Polymerization. Without shoving too much over the fence, I will show a few examples and at least one in each category.

Step Growth

Watanabe Macromol. Chem. Rapid Commun. 1993, 25, 209.

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Polyamides open vessel mw in high boiling high dielectric solvents

Chiral pyromellitoyl polymers a column materials Mallakpour J. Appl. Polym. Sci. 2004, 91, 516.

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Poly(amide imide)s

Polyanhydride synthesis is typically a two-step conventional approach over several days. This was shortened to one-step microwave method which took place in minutes. Mallapragada Macromol. Rapid Commun. 2004, 25, 339.

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Polyanhydride microwave approach

And just to let you know that pretty standard C-C coupling reactions work just fine Carter Macromolecules 2002, 35, 6757.

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microwave C-C coupling polymerizations

Ring-Opening

Significant rate enhancement over conventional heating Ritter Macromol. Rapid Commun. 2005, 26, 160-163.

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Cationic ring opening microwave polymerization

Free Radical

Microwave and microwave under radical generating conditions promote different pathways — both accelerated reactions considerably (in an oil bath the acrylamide formation did not occur, both polymerized in minutes). Ritter Macromol. Rapid Commun. 2005, 206, 349-353.

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Free Radical microwave polymerization

Now go take a look through some of what these chemists do and see if you can find some reactions that might be used in their world. It’s fun to see if the things we do day-to-day can be transfered into other areas of research.

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