The reactions of polystyryl. (PSt) radical and polystyryl dithiobenzoate (PSt-SCSPh) were modeled by those of 1-phenylethyl (PE) radical and 1-phenylethyl dithiobenzoate (PE-SCSPh). The low-mass homologues, which model the 3-arm star polymers possibly produced by the cross-termination between the PSt radical and the (intermediate) adduct radical of PSt(.) with PSt-SCSPh, were isolated and characterized by H-1 and C-13 nuclear magnetic resonance (NMR) spectroscopies, matrix-assisted laser desorption ionization time-of-flight mass spectroscopy (MALDI-TOF-MS), and elemental analysis. The low-mass model 3-arm stars were stable at 100 degreesC.