Cationic Polymerization of a-Methylstyrene in Solution

Safetyprecautions Befote 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 freed 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. 

Anionic Poiymerization with Organometaiik 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 unnecessary. 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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