The swelling degree of the copolymers was measured by calculating the water uptake of the wet and dried samples according to formula (2) and the results are presented in Figure . During the 20-day swelling degree study, an initial decrease followed by subsequent increase in polymer swelling after 10 days can be attributed to experimental consideration. Since the films are subjected to gentle wiping during measurements, some water could be retained. Also, as the mechanism of the degradation of PBS PBSbase polymers are erosion, which results in surface cracks and holes, can facilitate to entrap the residual degradation media. The results also indicates that degree of swelling increases at day 1 and 2 up to 6-7% and is higher for copolymers containing PEG. Then, the material's swelling decreased and stabilized at 5% after 20 days. This may indicate that hydrophilic PEG is leached out due to increased surface wettability of PBS-DLS copolymers. We already demonstrated in our earlier studies, that PEG is turning the surface of PBS-DLS copolymers from hydrophobic to hydrophilic, as demonstrated by the changes in water contact angle , . The presence of PEG introduces a distinct molecular structure with hydrophilic properties, enhancing the water uptake capacity of the copolymer. This increased water absorption, in turn, facilitates greater accessibility of the lipase enzyme to the ester bonds in the polymer matrix, which promotes water penetration into the polymer structure, effectively amplifying the hydrolysis rate of ester bonds. These results support hypothesis that a higher surface wettability leads to faster swelling . It's also worth mentioning that the absence of PCL samples beyond the 4th day is attributed to their complete degradation within this period.