To obtain quantitative information about the degradation processes of PBS-DLS copolymers and their PEGmodified counterparts of varying segmental compositions, films weight loss was measured, including PCL as a control. The choice of PCL as a reference material was made based on its well-established use in biomedical applications, as documented in the literature , emphasizing its relevance for material development in the biomedical field. The tests were conducted in the presence of active enzymes (25 U/mL). The film weight loss of the polymers was monitored over time, and the relative degradation rates were calculated according to formula (1). Figure shows the calculated mass loss of the copolymers during the enzymatic degradation at 37 °C thus indicating their susceptibility to degradation. It can be seen that the PBS-DLS copolymers showed a very low mass loss of approximately 0.012% per hour for the samples with different hard segment ratios (60 and 70 wt.%) with a final 6% mass loss after 20 days. The copolymers containing lower amount of hard segments (60 wt.%) and PEG showed a weight loss of around 10%, while copolymers with a higher hard segment ratio (70 wt.%) showed a weight loss of around 8%. There results confirm that PEG is boosting PBS-DLS films degradation in hydrolytic medium containing enzyme. It is reported that pure PBS did not lose weight after one year of incubation in enzymatic degradation study using lipase . However, it is important to note that different conditions, such as the choice of degradation media, temperature, and distinct types of PBS with variations in molecular weights, sources, and geometry can influence the degradation behavior of the PBS . Furthermore, the diversity in enzymatic conditions, encompassing factors like temperature, stirring, shaking, enzyme density, and activity, among others, can contribute to variations in PBS degradation results . This emphasizes the significant impact of introducing soft segments into the molecular structure of PBS, resulting in an increased rate of degradation, which is enhanced further by the hydrophilic PEG. Overall, the degradation rate of copolyesters is influenced by various factors, including their chemical composition, structure, physical properties, and surface characteristics. For example, previous research has consistently highlighted the influential role of substrate shape and inherent surface area-to-volume ratio in dictating the biodegradation rate of polymers . Films exhibit a slower degradation rate compared to nano-and microfibers due to differences in their surface area. This fundamental principle is further exemplified in our study involving PBS-DLS films. In a comparative analysis with our previous study employing PBS-DLS 70-30 wt.% nanofibers, utilizing the same lipase enzyme and enzymatic degradation process, remarkable differences in mass loss become evident. The nanofibers in our earlier study exhibited a substantial 40% mass loss after 20 days of enzymatic degradation . Intriguingly, in our study employing PBS-DLS 70-30 films, the mass loss was approximately 6% over the same time frame. This difference underscores the critical importance of available surface area in facilitating water and enzyme to access polymer matrix. Another contributing factor is the chemical composition, in which the hydrophilic surfaces allow easier accessibility of water molecules into the structure compared to hydrophobic surface, resulting in improved biodegradability .