AbstractThis study investigated the effects of poly(ethylene glycol) monoacrylate (PEGMA) on the properties of poly(ethylene glycol) diacrylate (PEGDA)‐co‐PEGMA hydrogel networks. The PEGMA materials utilized were similar to ligand‐linked materials typically copolymerized with PEGDA for use as tissue engineering scaffolds. PEGDA (5–20% wt/wt, 6 kDa) and PEGMA (0–20% wt/wt, 0–43 mM, 5 kDa) were copolymerized by photo‐initiated free radical polymerization and the mass swelling ratio and shear modulus of the resulting hydrogels were determined. Increasing the prepolymerization concentration of PEGMA decreased the swelling ratio by up to 42 ± 1.6% and increased the shear modulus by up to 167 ± 29.3%, suggesting that PEGMA enhanced gel cross‐linking. Analysis of the effective number of cross‐linked chains per PEGDA, calculated independently from swelling and mechanical data, indicated each PEGDA participated in more cross‐links as PEGMA was added. The results suggest that PEGMA‐co‐PEGDA gels can be formed with higher concentrations of PEGMA‐tethered ligands than previously reported allowing the formation of scaffolds with a rich diversity of biological functionalities without sacrificing the integrity of the gel network. © 2009 Wiley Periodicals, Inc. J Biomed Mater Res, 2010