| Abstract
| - In order to elucidate the structure of intermediate speciespresent during the early stagesof “living” anionic polymerization, the aggregation behavior ofstyryllithium head groups[RCH2CH-(C6H5)Li+]in benzene was investigated by small angle neutron scattering (SANS).The monofunctional lipophobicanionic head group was found to self-assemble in a first step to dimersand tetramers. The concentrationdependent equilibrium between these species was quantitatively analyzedby using the form factors of aGaussian linear coil and star, respectively. These results seem tocontradict a mechanistic viewpoint ofanionic polymerization that dates to 1960. Therein the dimer wasassumed to be the maximum allowableaggregation state for this head group. In addition, the SANStechnique has shown that the intermediatescale structures can also form large scale self-assembled aggregates(Rg ≅ 103 Å) whose scatteringbehaviorcan be analyzed in terms of a form factor for a mass fractal structurerecently proposed by Beaucage.
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