The development of colloidal delivery systems from degradable polyurethanes (PU) has attracted increasing interest as the highly variable synthetic chemistry of PU may be exploited to generate polymers having properties ranging from very soft elastomers to very rigid plastics. In this work, the synthesis of PU nanoparticles using isophorone diisocyanate, castor oil, and poly(ϵ-caprolactone) as monomers and containing high amounts of vegetable oils as açaí oil and crodamol GTCCwas studied. The effect of surfactants Tween 80 and sodium dodecyl sulfate (SDS) and of poly(ethylene glycol) molar masses 400, 600, and 1000 g/mol on the stability, size, and nanoparticle morphology was evaluated. Stable dispersions with sizes between 50–70 nm and 170–250 nm were achieved when, respectively, SDS and Tween 80 were used as surfactant. The polyol type used in the step polymerization in miniemulsion had a major effect on the molar mass of the resulting PU nanoparticles. The effect of poly(ethylene glycol) molar masses was more pronounced when Castor oil and Tween 80 were employed. Increasing the molar mass of PEG increased the average particle size and the molar mass of the PU. Finally, a strong reduction of the molar mass of the PU nanoparticles was observed in degradation assays when those were maintained during 30 days at 37°C and pH 7.0.
Practical applications: Using natural renewable oil as polyol to obtain polyurethane nanoparticles combined with incorporation of other vegetable oil therein showed good results in terms of molar mass and nanoparticle size. The simple and straightforward procedure to prepare polyurethane nanoparticles containing vegetable oils by step polymerization in miniemulsion contributes to improve the application range of these polymers.