Biodegradable hydrogels have become a rapidly expanding area of research for biomedical applications. Poly(beta-amino ester) (PBAE) biodegradable hydrogels, in particular, have been studied extensively because of the ease of synthesis and range of properties exhibited. In this work, PBAE macromers were created with poly(ethylene glycol) diacrylate (PEGDA), diethylene glycol diacrylate (DEGDA), and isobutylamine. Many methods have been presented that allow control over the resulting hydrogel behavior. Here, properties were varied by combining multiple diacrylate components in the macromer synthesis step (single macromer (SM)) or through the combination of multiple macromers prior to polymerization (double macromer (DM)). The exhibited properties are a result of the hydrophilic/hydrophobic contributions of the different diacrylate molecules to the macromer. The SM systems exhibited linear degradation profiles, the rate of degradation increased as the PEGDA concentration increased. DM systems exhibited a multiphase degradation profile as a result of the combination of macromers with different hydrophilic properties. (c) 2013 Elsevier Ltd. All rights reserved.