polymerization
Polymer Chemistry Course, KTE 080, 2014
Patric Jannasch
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Laboratory procedures in polymer chemistry
Polymer & Materials Chemistry
1. Free Radical Bulk Polymerization of Styrene
This protocol describes the bulk polymerization of styrene at 60 oC using 2,2´azobisisobutyronitril (AIBN) as an initiator. The monomer styrene first has to be purified before it can be used. The purification is performed in order to remove inhibitors and impurities, which can have a detrimental effect on the reaction. Styrene is purified by passing the monomer through a column of activated basic aluminum oxide and by this treatment the inhibitors and impurities are adsorbed. The styrene used in this laboratory experiment has already been purified in this way, and has then been kept in a refrigerator to prevent thermal auto-initiation of the monomer. In total 8 mL of the desired mixtures of initiator and styrene and pure styrene are added to reaction test tubes provided with glass stopcocks. A typical initiator concentration is around 1-8 g/L. The test tubes are shaken in order to properly homogenize the mixtures. Next, the tubes with the glass stopcock are secured with springs. In order to purge (remove) the oxygen, which will otherwise interfere with the polymerization, the tubes are evacuated using a vacuum connection, and are then filled with pure nitrogen gas. This process is repeated three more times to make sure that all the oxygen has been removed.
The polymerization reactions are performed in a heated water bath at 60 C for 2 hours. Note the exact reaction time in seconds! After 2 hours the polymerization is stopped by immersing the test tubes in an ice bath. The contents in the tubes are dissolved in 40 mL of toluene and the different polymers are then precipitated by adding the solutions slowly, drop-by-drop, into 400 mL of methanol under vigorous stirring. It is very important that the solution is added dropwise
Patric Jannasch
————————————————————————————————
Laboratory procedures in polymer chemistry
Polymer & Materials Chemistry
1. Free Radical Bulk Polymerization of Styrene
This protocol describes the bulk polymerization of styrene at 60 oC using 2,2´azobisisobutyronitril (AIBN) as an initiator. The monomer styrene first has to be purified before it can be used. The purification is performed in order to remove inhibitors and impurities, which can have a detrimental effect on the reaction. Styrene is purified by passing the monomer through a column of activated basic aluminum oxide and by this treatment the inhibitors and impurities are adsorbed. The styrene used in this laboratory experiment has already been purified in this way, and has then been kept in a refrigerator to prevent thermal auto-initiation of the monomer. In total 8 mL of the desired mixtures of initiator and styrene and pure styrene are added to reaction test tubes provided with glass stopcocks. A typical initiator concentration is around 1-8 g/L. The test tubes are shaken in order to properly homogenize the mixtures. Next, the tubes with the glass stopcock are secured with springs. In order to purge (remove) the oxygen, which will otherwise interfere with the polymerization, the tubes are evacuated using a vacuum connection, and are then filled with pure nitrogen gas. This process is repeated three more times to make sure that all the oxygen has been removed.
The polymerization reactions are performed in a heated water bath at 60 C for 2 hours. Note the exact reaction time in seconds! After 2 hours the polymerization is stopped by immersing the test tubes in an ice bath. The contents in the tubes are dissolved in 40 mL of toluene and the different polymers are then precipitated by adding the solutions slowly, drop-by-drop, into 400 mL of methanol under vigorous stirring. It is very important that the solution is added dropwise