In a small vial, the DME crosslinker (10 wt% in terms of monomer+crosslinker) was dissolved in the lactate ester methacrylate monomer (90 wt % in terms of monomer+crosslinker). Methacrylic acid (10 wt% in terms of both monomer + crosslinker) and BAPO (2 wt% in terms of all methacrylated species) were added. The formulation was ultrasonicated for 10 -30 min until all species fully dissolved. This formulation was adapted for MeLMA and ELMA. When adopting the formulation for BuLMA, the quantities were calculated based on mol instead of weight to ensure a comparable monomer to crosslinker ratio resulting in a formulation of BuLMA:DME in a mol ratio of 93:7 (set as 1 eq.), 0.22 eq. MA and 0.01 eq. BAPO.