To explore the relationship between
thermal properties of a polymer
and the biological performance of the resulting nanoparticle, all
other parameters, including the hydrophobicity, should be kept constant.
For this purpose, a gradient and a block copolyester were tailor-made
via the triazabicyclodecene catalyzed ring-opening copolymerization
of δ-valerolactone (δVL) and δ-decalactone (δDL)
to match the hydrophobicity of poly(ε-caprolactone) (PεCL).
The degree of crystallinity of the semicrystalline materials was significantly
reduced due to the incorporation of amorphous PδDL segments,
as confirmed by dynamic scanning calorimetry. Atomic force microscopy
revealed short and randomly oriented crystals in the gradient copolymer
but longer and parallel aligned crystals for the block copolymer and
PεCL. The stiffness of nanoparticles (D
h ≈ 170 nm) prepared from the polyesters correlated
to the bulk crystallinity. The set of nanoparticles with constant
hydrophobicity and size will facilitate direct access to the influence
of the nanoparticle crystallinity on biological processes such as
enzymatic degradation, drug release, and cellular uptake.