Novel lactide-based poly(ethylene glycol) (PEG) polymer networks (GL9-PEGs) were prepared by UV copolymerization of a glycerol-lactide triacrylate (GL9-Ac) with PEG monoacrylate (PEG-Ac) to use as scaffolds in tissue engineering, and the surface properties and biocompatibility of these networks were investigated as a function of PEG molecular weight and content. Analysis by ATR-FTIR and ESCA revealed that PEG was incorporated well within the GL9-PEG polymer networks and was enriched at the surfaces. From the results of SEM, AFM, and contact angle analyses, GL9-PEG networks showed relatively rough and irregular surfaces compared to GL9 network, but the mobile PEG chains coupled at their termini were readily exposed toward the aqueous environment when contacting water such that the surfaces became smoother and more hydrophilic. This reorientation and increase in hydrophilicity were more extensive with increasing PEG molecular weight and content. As compared to GL9 network lacking PEG, protein adsorption as well as platelet and S. epidermidis adhesion to GL9-PEG networks were significantly reduced as the molecular weight and content of PEG was increased, indicating that GL9-PEG networks are more biocompatible than the GL9 network due to PEG's passivity. Based on the physical and biological characterization reported, the GL9-PEG materials would appear to be interesting candidates as matrices for tissue engineering. [on SciFinder (R)]