<p>Poly(trimethylene carbonate) (PTMC) is a biodegradable polymer that is widely utilized in biomedical fields because of the soft mechanical properties conferred by its low glass transition temperature. However, its application is limited by the lack of reactive sites on its backbone for chemical modifications. To overcome this limitation, a copolymer, poly(trimethylene carbonate-r-5-methylene-1,3-dioxane-2-one) (PTMC-r-PexTMC), was developed as a platform for postpolymerization functionalization. Using thiol-ene click chemistry, diol and carboxylic acid groups were grafted onto PTMC-r-PexTMC at levels ranging from 1 to 30 mol% to tailor its hydrophilicity and surface compatibility. Thermogravimetric and contact angle analyses revealed that both the thermal stability and hydrophilicity increased with the degree of functionalization. Importantly, copolymers containing 30 mol% diol units inhibited platelet adhesion more effectively than those with equivalent carboxylic acid content did, indicating that both hydrophilicity and surface charge influence biocompatibility. Further studies involving degradation in PBS and doxorubicin release confirmed the potential of these functional groups to modulate polymer performance. These findings highlight the value of surface modification in increasing the biocompatibility of polycarbonates for advanced medical applications.</p>