Preparation of Poly a -Methylstyrene

Poly(cx-methylstyrene) having a Mn 300,000 daltons with of PDI 1.06 was prepared using sec-butyl lithium. The process entails initially treating the monomer with sec-butyl lithium to dry and to neutralize impurities while monitoring this process by UV. The monomer was then re-treated with butyl lithium, THF, and toluene and polymerized 24 hours. The material is intended for inertial confinement chambers in fusion experiments. 

A 100-ml reactor connected to a cryostat equipped with a UV cell was charged with 55 ml of toluene and a-methylstyrene (22 g). While monitoring by UV, the monomer was dried by the dropwise addition of s-butyl lithium at ambienttemperature, resulting in a slightly yellow coloring of the monomer. The mixture was then cooled to —25°C, treated with s-butyl lithium (0.073 mmol), stirred for 4 hours after which 10 ml of THF 

Moore [1] prepared polystyrene having a Mn of 130,000 daltons with a PDI of 1.05 by initially drying the monomer and neutralizing impurities with n-butyllithium prior to polymerization. n-Butyl-lithium was also used with potassium t-amyloxide by Malanga [2] in preparing ultra-pure poly(a-methylstyrene). 

Andrekanic [3] prepared poly(a-methylstyrene) using tin(IV) chloride as initiator in toluene with unpurified plant grade a-methylstyrene. 

Poly(butadiene-b-a-methylstyrene-b-styrene) was prepared by Tung [4] using sec-butyl-lithium and l,3-di(l-phenylethenyl)benzene. 

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The first publication on the use of 1,1-diphenylalkyllithiums as initiators for diene or styrene polymerization is the pioneering study of Morton and Fetters [49] on the preparation of poly(a-methylstyrene-btock-isoprene-f lock-a-methylstyrene) using the dilithium dimer of 1,1-diphenylethylene, 1,4-di-lithium-1,1,4,4-tetraphenylbutane (6) (see Scheme 4). The dilithium initiator... 

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