142 Advances in Polymer Science Editorial Board: A. Abe. A.-C ...

212 J. Roovers, B. Comanita
Scheme 14
than the focal group (see Scheme 14d). This transesterification is performed in
the melt at 225 ˚C and 0.03 Tor [123].
Living anionic polymerization has been used to place a central polystyrene
chain between two dendrimers [124]. Prior to the coupling reaction at –78 ˚C
the polystyrylpotassium reactivity is reduced by end-capping with diphenylethylene
(Scheme 14e).
The single focal point of the dendrimer can be used to initiate the polymerization
of monomer, e.g., of e-caprolactone [125] (see Scheme 15a). The efficiency
of the [G-4]-OK initiator is 100%. The polymerization is essentially complete
in 6 min at 0 ˚C. Experimental and calculated MWs agree and the MWD is narrow.
At longer times, Mn remains constant but the MWD increases due to trans-