Self-assembly of polyesters like PlLA and PdLA into stereocomplexes (SCs) is an interesting approach to tailor physical properties of polymeric nanoparticles without affecting their hydrophilicity. Here, we use the stereocomplexation of P(lLA-stat-EtGly) and P(dLA-stat-EtGly) (EtGly: 3-ethylglycolide) to tune the melting temperature (Tm) and degree of crystallinity (wc) of the bulk polymer. Using time-dependent blending experiments and characterization techniques, such as dynamic light scattering, wide-angle X-ray spectroscopy, differential scanning calorimetry, and atomic force microscopy, we tested the hypothesis that the amount of SCs within the nanoparticles impacts their mechanical properties. Our results show that Tm and wc can be adjusted via the EtGly content. Interestingly, mechanical properties of the nanoparticles depend on the EtGly content as well as the self-assembly time of SCs before nanoparticle formation. This offers a high potential for their application in drug delivery, where their tunable properties will allow to adjust degradation and drug release behavior.