Macromonomers, polystyrene anionic living polymerization

The synthesis and purification of polystyrene methacryloyl macromonomers (PS-MA) in the molecular weight range Mn= 1000-2000 g mol 1 by living anionic polymerization of styrene (S), termination with ethylene oxide (EO), and subsequent reaction with methacrylic chloride has already been described in detail elsewhere [180] (see also Scheme 16). In this context it has to be emphasized that the hydroxyethyl-terminated PS-MA macromonomer precursor (PS-OH) as obtained after purification of the crude PS-OH by silica column chromatography (cyclohexane/dichloromethane 1/1 v/v) and as charged in the PS-MA synthesis still contains up to about 15 wt-% of non-functionalized polystyrene (PS-H). This PS-H impurity of the PS-MA macromonomer does not interfere with the PS-MA synthesis and the subsequent TBA/PS-MA copolymerization and is easily and conveniently removed from the resulting PTBA-g-PS graft copolymer (see below). 

Star polymers exhibiting three different branches (PS, PDMS, and poly( er -butyl methacrylate) were prepared in a similar way, the first being the preparation of PDMS macromonomers containing a terminal nonpolymeriz-able DPE entity. Thus, a living PS is reacted with the PDMS macromonomers to create active sites on DPE. These sites served subsequently as initiators for the anionic polymerization of tert- mXy methacrylate [89]. Stadler and coworkers have used that reaction to generate polystyrene-arm-polybutadiene-arm-poly(methyl methacrylate) [90]. 

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