ARTICLEThis journal is Poly(ethylene glycol) [1, PEG~4(OH) 2 , M n ~ 200], glycerol ethoxylate [2, PEG~2 1 (OH) 3 , M n ~ 1000] and pentaerythritol ethoxylate [3, PEG~1 5 (OH) 4 , M n ~ 797] react directly with phenyl-C 61 -butyric acid methyl ester (PCBM), in the presence of dibutyltinoxide (DBTO) catalyst at 140 o C, to give a mixture of fullerene [C 60 ] end-capped PEGs via transesterification.Among these PEG linkers, only PEG~4(OPCB) 2 (4a) (OPCB: ester oxygen linked phenyl-C 61 -butyryl group) was successfully isolated from the crude product mixture in the fully endcapped form. Fully acylated PEG~2 1 (OPCB) 3 (5) and PEG~1 5 (OPCB) 4 (6) could not be separated chromatographically from incompletely reacted species due to the polydispersity in branch lengths. This purification challenge was overcome by using a monodisperse branched core, 1,3,5-tris(octagoloxymethyl)benzene [7, PEG 24 (OH) 3 ] to give a monodisperse trisfullerene homostar, PEG 24 (OPCB) 3 (8). The structures of the bis-and tris-fullerene products were confirmed by MALDI-TOF mass spectrometry and 1 H NMR spectroscopy with supporting FTIR and UV-vis spectroscopic analysis.