The hydrolytic stability of the monomers was then measured in D2O (1M HEPES buffer, 37 °C) at pH 7.4 (Figure ). The 31 P NMR resonance signal remained unchanged for the non-amino acid containing PdA monomer 3 throughout the observed period of 229 days (SI-13), suggesting considerable resistance towards hydrolysis for this compound. Meanwhile, the amino acid-containing monomers showed clear hydrolysis through cleavage of the P-NH bonds to give phosphate, as evidenced by increasing peaks at 1.5 ppm (Figure ). The phosphate and amino acid degradation products were also confirmed by MS spectrometry (SI-14). Moreover, the rate of hydrolysis was observed to be faster for 2 Gly-APdA than 1 Ala-APdA (Figure ), which is assigned to the shielding effect of the methyl α-substituent. As it is reported that phosphorodiamidates are acid-labile , we also studied the hydrolysis at pH 3.0 (1M Citric Acid/D2O). A considerable acceleration in hydrolysis was observed for all monomers at this pH (see figure and SI 15). A number of biomedical applications require polymer materials that degrade at lower pH, making this triggered degradation an interesting property . The novel APdA monomers were then subject to photopolymerization with a stoichiometric ratio with the commonly used trithiol (1,1,1-tris-(hydroxymethyl)-propanetris-(3-mercaptopropionate) (TMPMP). Similar systems have been widely studied with organic alkynes , acrylates and vinyl esters for the preparation of photopolymers for a range of biomaterials applications. The monomer conversion (MC) was analysed by RT-FTIR spectroscopy, in which the reaction was followed by a decrease in the alkyne band at 2130 cm -1 (Figure , full spectrum SI-16). In addition, the depletion of the thiol moieties (2570 cm -1 ) and the formation of vinyl sulfide groups (2095 cm -1 ) as intermediates can be detected. Gly-APdA and Ala-APdA show slightly higher final MC than PdA (SI-17 and SI-18). The photokinetics were measured by photoDSC (Figure and SI-19) with 5 wt% TPO-L as initiator. The three monomers all showed reasonable curing kinetics, with tmax between 8.6 and 9.7 seconds. The bulk mechanical properties of the resulting polymers were analysed and displayed in table and depicted in SI-20-21. The values are comparable to similar thiol-yne-based polymers with TMPMP but could be improved significantly in future generations through the use of alternative thiol comonomers . To demonstrate the applicability of the novel monomers for photopolymerisation, we prepared samples for multiphotolithography (MPL). Figure shows a 30x30x1.6 µm 3 grid fabricated with a custom-made lithography setup further described in supporting information. The grid sidewalls consist of 4 partially overlapping excitations voxels (~0.5 µm height for each) written on top of each other to enhance stability. MPL was performed with excitation power of 31 GW cm -2 and 7 µm s -1 writing speed (excitation wavelength: 515 nm fs-pulsed), illuminating each voxel twice.