Advances in diagnostic imaging, as well as surgical technique and instrumentation have synergistically enabled rapid growth of minimally invasive procedures. These procedures have advantages over traditional surgical techniques, such as shortening the treatment time and reducing the risk of complications. These surgical approaches motivate further research into wide range of injectable materials that can enable tissue repair, drug delivery, cell therapy, sensing, imaging, etc. Of particular interest are materials that can be injected as a liquid and then crosslinked in situ, under different stimuli, such as light, temperature, or pH. While hydrogel based materials have been most popular, curable elastomeric materials can be well suited for specific tasks, such as heart muscle repair after infarct or hernia repair. Towards this aim, we have previously developed injectable and photocurable ester-urethane macromonomers based on fatty acid derivatives obtained from vegetable oils. Polyurethanes are already widely used in medical and pharmaceutical applications due to their favorable safety profiles and mechanical properties, as well as potential for biodegradability. In the case of our injectable macromonomers, once photocured, the obtained elastomeric materials exhibit similar mechanical properties to human soft tissue (i.e. abdominal wall), along with slow enzymatic and hydrolytic degradation. Overall, these materials displayed low toxicity and similar immune response to polylactic acid in a rabbit model, making them promising for minimally invasive surgical procedures. However, in our previous work the ester-urethane macromonomers were synthesized with use of organotin-based catalyst, dibutyltin dilaurate (DBTDL). Overall, tin-based catalysts are commonly used for the synthesis of polyesters and polyurethanes as elastomers and coatings.