Soft amphiphilic polyesters obtained from PEGs and silicon fatty compounds: structural characterizations and self-assembly studies

Transesterification polymerizations between a silicon fatty ester derived from methyl 10-undecenoate and polyethylene glycol (PEG) monomers generate amphiphilic biopolyesters with maximum molecular weights within two hours of reaction. The characterization of these products by FT-IR, 1H NMR and 13C NMR spectroscopies confirmed that these structures result from ester formation. These biopolyesters demonstrated thermal stability at temperatures higher than 400 °C, with an increase in the heat of fusion (ΔHfus) and melting temperature (Tm) as the PEGs' molecular weight increased. Self-assembly studies in water through fluorescence and TEM techniques revealed micelle formation, with a low critical aggregation concentration, for biopolyesters that incorporated PEGs with a molecular weight between 1000 and 3000 g mol−1. The micelle sizes, determined via dynamic light scattering analysis, increased with the PEG length, with diameters between 70 and 190 nm. Fibre materials were prepared from biopolyesters containing PEGs with molecular weights higher than 1500 g mol−1 and were studied via polarizing optical microscopy.