Vinyl Acetate to Polyvinyl Acetate
Estimated Time (including set-up): 1 hour

Introduction

"A polymer is a macromolecule composed of repeating structural units connected by covalent bonds" (Wikipedia). White glue or polyvinyl acetate is a polymer composed of the repeating vinyl acetate structural unit. To produce the polymer (polyvinyl acetate) on aqueous conditions is necessary the reflux of vinyl acetate, potassium persulfate and a surfactant (soap) at 80 ÂșC for 40 minutes. The water reacts along with the vinyl acetate in order to produce the polyvinyl acetate chain. The potassium persulfate is a catalyst which helps accelerate the reaction with out itself being consumed. Finally, the surfactant is used in order to bring the immiscible water and vinyl acetate together in order to react successfully. Potassium persulfate  it is used as initiator for the polymerization producing radicals, molecules highly reactive.

Figure 1. Polymerization Reaction

Potassium Persulfate acts as initiator forming the radicals as show on steps 1, 2 and 3 below to finally form the long chain polymer.

 

           

               

               Figure 2. Mechanism for the radical formation on the polymerization reaction.

 

Learning Objective

To understand the importance of each reagent in the reaction for producing polyvinyl acetate by understanding the effect the absence and presence of each reagent in the reaction has on the final product.


Materials

1. Ringstand

2. Round bottom flask clamp

3. 100 mL round bottom flask

4. 10 mL graduated cylinder

5. Vinyl acetate

6. Water

7. Surfactant (Soap)

8. Potassium persulfate, K2S2O8

9. A jacketed condenser with rubber hoses

10. Boiling chips or a Teflon coated magnet

11. Ring clamp

12. Voltage regulated heating well and/or a magnetic stirrer or magnetic stirrer/heating mantle

13. Magnetic stirrer if using a magnet to stir the reaction


Procedure

1. If you will be using a magnet to stir your reaction add the magnet to your round bottom flask by turning the flask on its side and

sliding the magnet into the flask. Dropping the magnet into the flask can cause it to break.

2. Clamp the round bottom flask to a ringstand.

3. In a well ventilated room or hood measure out the vinyl acetate indicated below for your experiment using a clean and dry

graduated cylinder.

4. Never return unused vinyl acetate to the original bottle!

5. Pour the vinyl acetate into the round bottom flask.

6. Measure out and add the indicated water to the round bottom flask.

7. Observe the solubility of vinyl acetate and water.

8. Add the indicated drops of detergent or surfactant to the flask.

9. Observe the solubility of vinyl acetate and water.

10. Weigh and add the indicated amount of potassium persulfate.

11. If you are using boiling chips add three at this time.

12. Connect the condenser to the round bottom flask and slowly start the water flowing in the jacket so that water in entering

through the bottom of the condenser and exiting through the top.

Image:CondenserSetUp.png

13. If you are using boiling chips place the round bottom flask with the condenser attached into the voltage regulated heating well

and secure the set up with two flask clamps, one on the round bottom flask and the other on the condenser.

Image:BoilingChipSetUp.png

14. If you are using a magnet put the voltage regulated heating well on top of the magnetic stirrer (or a magnetic stirrer/ heating

mantle can be used in which case a voltage regulator is not required) and lower the round bottom flask into the well secure the set

up with a two flask clamps, one on the round bottom flask and the other on the condenser. You can begin stirring by turning the knob

labeled "STIR".

Image:MagnetSetUp1.png Image:MagnetSetUp2.png

15. Heat the round bottom flask by increasing the voltage on the regulator slowly (or by turning the knob labeled "HEAT" on the

magnetic stirrer/ heating mantle) so that liquid drips back into the mixture (refluxes) and does not escape out through the top of

the condenser.

16. Reflux the reaction for half an hour being careful not to burn the reaction.

17. Observe what happens to the reaction over the half our time period.


 

Image:PVACTable.png

 


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