Polyisobutylene (PIB) phenol (meth)acrylates were produced by reacting di- or triphenol-terminated PIB with (meth)acryloyl chloride. H-1 NMR, GPC, and MALDI-TOF MS characterization showed that meth(acrylate) end-functionality was 2 and 3, respectively, and that targeted molecular weights and relatively low polydispersities were achieved. Comparative aliphatic PIB triol triacrylate was prepared by end-quenching living polyisobutylene with 4-phenoxy-1-butyl acrylate. A photopolymerization study of PIB diphenol di(meth)acrylates with M-n about 3000 g/mol, PIB triphenol tri(meth)acrylates with M-n about 4000 and 10 000 g/mol, and control aliphatic PIB triol triacrylate with M-n about 10 000 g/mol was conducted. Darocur 1173 and Irgacure 819 and 651 photoinitiators were studied, and FTIR reaction monitoring showed that Darocur 1173 afforded the highest rate of photopolymerization and final conversion, apparently due to its higher solubility in PIB. At M-n congruent to 4000 g/mol, the rate of photopolymerization and conversion of PIB triphenol triacrylate was faster than that of PIB triphenol methacrylate under the same conditions; at M-n congruent to 10 000 g/mol, PIB triphenol triacrylate, PIB triphenol trimethacrylate, and aliphatic PIB triacrylate all showed the same high rate of photopolymerization, which was higher than any rate observed at M-n congruent to 4000 g/mol. Similarly, PIB triphenol tri(meth)acrylate at M-n congruent to 4000 g/mol displayed a higher rate of photopolymerization and double-bond conversion than PIB diphenol di(meth)acrylate at M-n congruent to 3000 g/mol, although they have similar chain end concentrations. This phenomenon was attributed to reduced diffusional mobility at higher Mn, resulting in decreased rate of bimolecular radical termination and autoacceleration. Tg of UV-cured PIB networks decreased as M-n of PIB macromer increased regardless of end-group type, and thermal stability of cured networks remained constant regardless of end-group type. Mechanical properties were characteristic of rubbery networks, but weak, apparently due to low Mn and low PDI of the starting macromers and lack of chain entanglements. Networks from macromers with M-n congruent to 10?000 g/mol gave higher elongations, but lower Youngs moduli, compared to those from macromers with M-n congruent to 4000 g/mol.