The chain transfer constant to polymer (C-p) for poly[11-(4'-cyanophenyl-4"-phenoxy)undecyl acrylate] was measured directly by the Mayo method by following the decrease in molecular weight at low monomer conversion by gel permeation chromatography of poly(methyl acrylate) generated in the presence of increasing amounts of 11-(4'-cyanophenyl-4"-phenoxy)undecyl propionate (C-P = (6.62 +/-0.476) x 10(-3)) and 11-(4'-cyanophenyl-4"-phenoxy)undecyl isobutyrate (C-p = (4.27 +/- 0.858) x 10(-3)) as model compounds that mimic one repeat unit of the polymer and oligo[11-(4'-cyanophenyl-4"-phenoxy)undecyl acrylate] with nine repeat units (C-P = (5.54 +/- 0.608) x 10(-3)) synthesized by atom transfer radical polymerization. The mean chain transfer constant, C-P = 5.48 x 10(-3), was used to calculate the extent of branching (p) in poly[11-(4'-cyanophenyl-4"-phenoxy)undecyl acrylatel (DPn = 37) synthesized by conventional radical polymerization: p = 0.0042-0.020 at 72-99% conversion, which corresponds to one branch per 6.4-1.4 chains, respectively, of 37 repeat units.