A summary of the mechanical properties of all of the obtained materials is presented in Figure , while representative stress-strain curves can be found in the Supplementary Information Figures S16-17. Overall, the results were broadly similar, with the differences possibly a consequence of manual sample preparation (both photocuring and cutting). It can be also observed that for the case of the non-organotin catalysts, the photocuring atmosphere (air vs argon) did not have a marked effect on mechanical properties. Overall, the tensile strength was measured up to 3.5 MPa, elongation was up to 120%, moduli at 2-3% strain and 5-6% strain were in the range of 2-6 MPa. However, in the case of the materials synthesized with both concentrations of the organotin catalyst DBTDL, the photocuring atmosphere did have an effect on the tensile strength and elongation at break: the values of these parameters obtained from materials cured under argon were approx. double those of materials cured in air. This may be explained by the oxygen inhibition having a negative effect on the photocuring process, and in result, in final material properties. We conclude that the mechanical properties of materials obtained using non-organotin catalysts indicate their potential in medical applications. While the values are higher than those reported for living human abdominal wall tissue, as measured during laparoscopic procedures, the values fall in ranges considered typical of "soft tissue" in the biomechanics literature: Young's modulus in the 0.1-10 MPa range and ultimate tensile strength and ultimate tensile strains in the range of 0.3-100 MPa and 10-120%, respectively . Further, compared to other materials intended for use in soft tissue engineering, like hernia repair, reported in the literature, our materials have approx. 10-times lower modulus of elasticity values . . As anticipated, the use of tin-free catalysts resulted in higher cell viability for all tested conditions (catalyst concentration and atmosphere), with a trend towards higher viability in the case of materials synthesized with ZnAc catalyst. As an organotin catalyst, DBTDL is known to be highly toxic and-equally importantly-is very difficult to remove from polymers during purification. Based on the literature, DBTDL can be estimated to have an IC50 of approx.