Polymerization of a-Methylstyrene in Solution

Safety precautions Before this experiment is carried out. Sect. 2.2.5 must be read as well as the material safety data sheets (MSDS) for all chemicals and products used. 

Monomeric a-methylstyrene is fi eed from phenolic inhibitors by shaking twice with 10% sodium hydroxide. It is then washed three times with distilled water, dried over calcium hydride, and distilled before use over calcium hydride under reduced pressure of nitrogen (bp 54 C/12 Torr). 

Methylene chloride is refluxed over P2O5 (best deposited on a solid carrier) for 1 h and then distilled into a dry receiver. 

2 Anionic Polymerization with Organometallic Compounds as Initiators 

For the polymerization of unsaturated monomers with organometallic compounds, the initiator concentration must generally be between 10 and 10 /mol of monomer cocatalysts are usually uimecessary. Polymerization frequently occurs at temperatures below 20°C. Raising the temperature increases the rate of polymerization, but usually decreases the tacticity or tactic content when stereospecific initiators are used. An induction period is rarely observed. 

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