Nanospheres Containing Urea: Photothermic Properties
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In the present research, nanospheres of chitosan (CS), maltodextrin, and sodium tripolyphosphate (STPP), loaded with urea, were synthesized by using an ionic gelation technique. In the nanosphere synthesis was used a central composite experimental design, obtaining nanospheres with an average size of 275 ± 32 nm and 27.5 mV zeta potential. The nanospheres were characterized by their hydrodynamic diameter, polydispersity index, nitrogen content, and thermal properties such as thermal diffusivity (α), effusivity (e), and conductivity (k); also melting temperature was obtained by differential scanning calorimetry. The thermal properties of nanospheres show that the sample with the smallest size has a thermal diffusivity value of (14.4 ± 0.4) × 10−8 m2·s−1 and a thermal conductivity value of (6.4 ± 0.1) × 10−1 W·m−1·K−1, and the obtained melting temperature was 157 °C. Higher concentrations of CS increase the values of these thermal properties, probably because chitosan interacts ionically with STPP forming a reticular network due to the opposite charges of both molecules.
KeywordsBiopolymers Ionic gelation Nanoencapsulation Thermal properties Urea
F. Mallon Mercado is grateful for the scholarship program granted by the National Council of Sciences and Technology (CONACYT) and the Institutional Support for Research Incentive Grant (BEIFI). Authors also thank the partial financial support from CONACYT through the Project No. 241330. We also are grateful to Ing. Esther Ayala from Physics Department, CINVESTAV-IPN, for her technical support in developing the experiments of the present study.
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