Preparation and Characterization of Melamine-Formaldehyde Resin Micro- and Nanocapsules Filled with n-Dodecane

Abstract

Capsules containing phase change materials (PCMs) have been widely studied for applications in heat transfer, heat storage and temperature control. The average diameter of encapsulated PCMs usually has a large effect on the physical properties of these functional materials. The aim of this study was to prepare and characterize encapsulated n-dodecane, a kind of PCM with a phase change temperature at about −10°C, in micro- and nanoscales via an in-situ polymerization method with melamine-formaldehyde resin (MF) as the shell. By analyses with scanning electronic microscopy, Fourier transform infrared spectroscopy and 13C nuclear magnetic resonance, it was found that the obtained capsules containing n-dodecane were on microns or several hundreds of nanometers size with spherical shape and smooth surface, and the agglomeration of the capsules was mainly dependent on the average diameters which was controlled by the stirring rate during emulsification of n-dodecane, as well as the concentration of the emulsifying agent and the reaction temperature. Thermogravimetric analysis showed that the n-dodecane capsules increased their thermal stability with decreased diameter. The results of differential scanning calorimetry showed that the supercooling degree of n-dodecane in nanocapsules was somewhat higher than that in the microcapsules, and the suppression of supercooling is considered.