A straightforward and versatile strategy for preparing a class of biodegradable and amorphous polyketoesters is reported. A series of ketone-containing diesters and diacids were combined with di(ethylene glycol) through condensation polymerization, achieving values of up to 10.1 x 10(3) g/mol. Glass transition temperatures ranged from -41 to -6 degrees C, rendering all of the materials liquid at room temperature. By including ketone groups in the repeat unit, facile postpolymerization modifications were possible by reaction with oxyamine-tethered ligands through the formation of an oxime linkage. Upon reaction with molecules that contain oxyamines, under mild conditions, these polymers can easily have a diverse set of side chains appended without coreagents or catalysts. The chemoselective oxime-forming coupling strategy is compatible with physiological conditions and can be done in the presence of a wide range of functional groups and biomolecules, including proteins and nucleic acids. We demonstrate the utility of this strategy by immobilizing a cell adhesive peptide (H2NO-RGD) to polyketoester films, creating cell adhesive elastomers. This immobilization strategy is synthetically flexible for designing and tailoring polymers for targeted biological applications.