Poly(ethylene glycol) (PEG) can serve as an electron-beam (e-beam) resist to modulate protein adsorption on and cell adhesion to surfaces. PEG preferentially crosslinks under e-beam irradiation to create microgels with controllable properties. Here, atomic-force, scanning electron, and confocal microscopies are used to study discrete microgels formed from solvent-cast PEG thin films by focused e-beams with energies between 2 and 30 keV and point doses between 10 and 1000 fC. Consistent with experimental findings, Monte Carlo simulation of electron energy deposition identifies three structures within each microgel: a highly crosslinked core near the point of electron incidence; a lightly crosslinked near corona surrounding the core; and a far corona at the PEG-Si interface. The nature and relative sizes of these three regions and, hence, the microgel-protein interactions depend on the incident electron energy and dose. The far corona creates protein-repulsive surface hundreds of nanometers or more from the microgel core. The highly crosslinked core is largely shielded by the near corona. These findings can help guide the choice of irradiation conditions to most effectively modulate protein-surface interactions via PEG microgels patterned by e-beam lithography. (c) 2013 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2013, 51, 1543-1554