I work with in situ synthesis to obtain hybrid materials (nanoparticles stabilized by polymer-surfactant aggregates), using the thermal decomposition of urea to form spinel metal oxide nanoparticles, corroborating the formation of quasi-spherical aggregates polymer-surfactant at the concentration of surfactant that was used (without metal cations and urea), however with the addition of metal cations and the urea, the system is not in balance at the end of the synthesis, there is not homogeneity.
It is well known that the formation of micelles by surfactants could be considered as a balance between the intermolecular interactions. In other words, the hydrophobic and hydrophilic properties play the major role for such behavior of micellization. But, your problem is raised from that at relatively high temperature of 70C such intermolecular interactions do not work which therefore affect the homogeneity of solution.
Dear Nubia,
you have a very complex mixture, which makes it difficult to point to one cause.
It seems, however, that the instability at the end of the synthesis is due to formation of too large particles or insufficient stabilization. Reduction of metal concentration, rapid cooling, change in surfactant or its concentration may solve the problem.
Thank you Rabah and Titus, I have been doing experimentation, and I found that the stirring rate plays an important role in the system, and the urea principally affects the formation of nanoparticles more than the aggregates formation, now i'm doing experiments at different heating rate, but I will see the results until the next week.
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