Abstract
Abstract Recently, the physical and chemical effects of ultrasound in polymeric materials synthesis have attracted great attention. This work presents the synthesis of novel polymeric materials by polymerization of isophorone diisocyanate with different polyols. Polymers were synthesized by step miniemulsion polymerizations, using ultrasound bath and thermostatic bath. The effects of ultrasound, temperature and polyol type were evaluated by Fourier transform infrared spectroscopy, gel permeation chromatography, dynamic light scattering and titrimetry. Polymerization under ultrasound bath showed that different reaction temperatures in the range between 50 °C and 80 °C directly influence the molecular weight of the polymers, urea/urethane formation and increase of diisocyanate consumption rate. In addition, different polyols used in polymerizations in miniemulsion had a significant effect on the characteristics of the resulting poly(urea-urethane) nanoparticles. Finally, ultrasound assisted polymerizations showed a faster diisocyanate consumption rate, but did not lead to enhanced molecular weights.
Highlights
Synthesis of new polymeric materials have attractedThe development of poly(urea-urethane) (PUU) has been the interest of researchers, chemical and pharmaceutical extensively studied in the last decades due to their excellent industries
When reactions were conducted under ultrasound bath, absence of absorbance at 2270cm-1 (N–C–O stretching vibration) indicates that all isocyanate groups were consumed during the reaction
In the reactions conducted in the thermostatic bath, the absorption band located at 2270 cm-1 was still found and that could be explained by the fact that these reactions were slower when compared with the same reactions in as ultrasound bath, thereby the isocyanate groups were not completely consumed at the end of reaction time
Summary
Synthesis of new polymeric materials have attractedThe development of poly(urea-urethane) (PUU) has been the interest of researchers, chemical and pharmaceutical extensively studied in the last decades due to their excellent industries. Droplets within a size range (from 50 to 500 nm), prepared in Urea groups may be formed in a secondary reaction with a system containing a dispersed phase (organic), continuous phase (aqueous), an emulsifier and a co-stabilizer[10,11]. To obtain this dispersion, a mechanism of high shear stress is required to break the monomer droplets into submicron droplets, reaching a steady state obtained by balancing the rates of coalescence and breakage of droplets that are kinetically, but not thermodynamically stable. The formed amine can rapidly react with an isocyanate group to generate a compound with a urea bond, modifying the final properties of PUU[22]
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