Photocrosslinkable and degradable polymers are finding a broad range of applications as drug-delivery vehicles, tissueengineering scaffolds, and in the fabrication of microdevices. [1][2][3] However, the synthesis of multifunctional macromers that form these degradable networks commonly involves multiple functionalization and purification steps, which makes the development of large numbers of polymers with diverse properties difficult. Here, we develop the first combinatorial library of degradable photocrosslinked materials. A library of acrylate-terminated poly(b-amino ester)s was synthesized in parallel via a condensation reaction that combines primary or secondary amines with diacrylates. This library of macromers was then photopolymerized to form degradable networks, with a wide range of degradation times (< 1 day to minimal mass loss after three months), mass-loss profiles, and mechanical properties (∼ 4 to 350 MPa). We believe this library approach will allow for the rapid screening and design of degradable polymers for a variety of applications. The spatial and temporal control afforded during photoinitiated polymerizations has motivated their wide application in the general field of biomaterials. [1,2] For example, photocrosslinkable hydrogels are used for the delivery of cells to injured tissues, [4][5][6][7][8] for the encapsulation and controlled delivery of biological molecules, [9][10][11] and for controlled fluid flow and cell confinement in microfluidics. [12,13] Additionally, highly crosslinked photopolymers are currently used in dentistry [14] and are being developed as bone-replacement materials [15,16] and for the fabrication of microdevices.[17] Many of these applications are only possible owing to the controlled nature of this type of polymerization. For example, photoinitiated control of polymerization allows for their application as injectable biomaterials [18,19] with a non-cytotoxic polymerization process.[20]Additionally, through use of masks and lasers, the spatial control of the polymerization process allows for unique patterning and construction of complex materials.[21]Numerous photopolymerizable and degradable materials have been developed, including polyanhydrides, poly(propylene fumarates), poly(ethylene glycol), and polysaccharides, [8,15,16,18] all utilizing multiple reaction and purification steps for synthesis of the photopolymerizable precursors. Despite this work, it has proven challenging to predict specific desirable properties (e.g., degradation and mechanics) from known chemical and structural details of the network precursors. These properties are essential in the design of degradable polymers. For instance, it may be desirable to synthesize a very hard material for some applications (e.g., orthopaedics), whereas a soft material is advantageous for other applications (e.g., tissue adhesive). [22,23] One potential solution to the inability to predict physical behavior is the generation of a higher-throughput approach to rapidly synthesize and screen photopolymerizable li...
