RESUMO
Theoretical studies on conformational analysis, geometry optimizations and frequencies for citrate at the MP2/LANL2DZ level portrait it as a promising candidate for a complexing agent for cadmium (II) ion (Cd2+) and cadmium sulfide (CdS). Natural Bond Orbital (NBO) charges, Delocalization Indices, HOMO/LUMO gaps and surfaces along with absolute electronegativity values were employed to analyze the interactions among the configurations obtained. The most stable structures involved the interaction between the LUMO of Cd2+/CdS and the most dense region of the HOMO of the citrate ion.
RESUMO
The reaction of cyclic carbonates with amines is the most attractive among the synthesis methods for isocyanate-free polyurethane. Non-isocyanate polyurethane films with SiO2 NPs fabricated by a sol-gel process are reported, where cyclic carbonates (CC) were produced under mild conditions by CO2 insertion in an epoxide complex in the presence of LiCl. A reaction of CC and polyamines was carried out in a low concentration polymer matrix of PVA. The materials were characterized by 1H-NMR, FTIR, UV-Vis, SEM, TGA, DTG, and a KD2 pro technique. polymer FTIR results are consistent with the literature, even with the use of a non-conventional methodology, where the found chemical interactions values were 3330, 2930 and 1637 cm-1. There are differences in the polymers' morphologies due to the presence and absence of SiO2 NPs according to SEM, where the spherical morphology and homogenous particle size distribution of NPs around 100 nm. According to TGA results, all polymers showed their last stage decomposition after 300 °C and polymers with higher concentration of NPs showed even better stability. Due to the obtained results, the polymers have the potential to be used for thermal insulation without negative effect on the environment.
