Free Radical Polymerization

Recomended Reading

Please read these informative pages from The Macrogalleria.

You may also find it beneficial to review Chapter Three (pages 198 - 334) in Principles of Polymerization by George Odian.

Goal

The goal is to for you, the enthusiastic lab student, to design and perform a free-radical polymerization.

Objectives

  1. Determine correct procedure for polymerization
  2. Calculate amount of initiator needed
  3. Calculate amount of chain transfer agent if necesarry
  4. Synthesize a vinyl polymer

Questions

Welcome to your first inquiry based lab. Let me explain again what is meant by an inquiry based lab. In a lab such as this, you will be asked to perform a specific task. In this case, your task is to polymerize your given monomer free-radically. What makes this lab different than others you have had before is that we will not tell you how to do it. Do not be afraid; if you read the Recomended Reading, you should already have all the necesarry information to perform the polymerization. You will use the knowledge you already have to design the reaction yourself.

How the heck am I supposed to design the reaction myself?

I'm glad you asked! The way you begin the experiment is by asking yourself questions about the experiment at hand. What are the components of the reaction? What is the mechanisim? Are there any safty concerns? What do I need to calculate? These are questions you should ask yourself every experiment. There are, however, more complicated questions you have to ask yourself: How much of this? When should I add that? This may seem like a herculean task right now, but by the end of the year, you should be able to do real research. Since it is your first lab, and you are likely unsure of how to begin, I will give you a few questions to ponder and begin your experiment.

Should I run the reaction in bulk or solution?

Will the solvent lead to chain transfer?

Will the reaction rate be to fast in bulk?

How muc initiator should I use?
How many radicals are formed by each initiator molecules?

How fast is initiation compared to propigation?

Is a chain transfer agent used?

How much monomer is used?

What is the target molecular weight?

How much chain transfer agent should I use?
What is the mechanism of chain transfer?

Is chain transfer desired?

At what temperature should the reaction be performed?
What is the dissociation temperature of the initiator?

What is the boiling point of the monomer?

What is the ceiling temperature of the polymerization?

How long should the reaction run?
What is the target conversion?

What is the target molecular weight?

These questions may or may not be all the questions you need to ask. There may even be some misleading questions, but that is the reality of science. You usually do not get it right the first time, and that is okay. You just take note of what went wrong and get back in the saddle. Also, do not get used to the important questions being asked for you. Soon, you will have to ask them yourself, but given this example, you should have no problem. Right?

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