Preparation and Characterization of Poly(melamine-urea-fbrmaldehyde) Tetradecanol Microcapsules Coated with Silver Particles

Abstract

A novel type of microencapsulated phase change materials (microPCMs) based on 1-tetradecanol (TD) core and silver-coated poly (melamine-urea-formaldehyde) (MUF) shell was successfully synthesized by in situ polymerization method followed by silver reduction. Fourier-transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), scanning electron microscopy with energy dispersive X-ray spectrometry (SEM/EDS), thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC) were used to characterize the chemical structure, morphology and thermal properties of the as-prepared silver-coated microPCMs. FTIR analysis confirmed the successful encapsulation of TD with MUF wall materials. The SEM and EDS results indicated that the prepared silver-coated MUF microPCMs exhibited uniform spherical shape with a perfect silver outer layer. From XRD analysis, the Ag metal dispersed on the surface of microcapsules presented the form of elementary substance. The deposition weight of silver particles on the microcapsule surface increased with increasing the amount of silver nitrate, as indicated by EDS tests. The DSC results indicated that the melting temperature and the melting latent heat of microPCMs modified with 0.7 g of silver nitrate in 150 mL aqueous solution were 39.2 °C and 126.6 J·g⁻¹, respectively. Supercooling of the microPCMs coated with silver particles was effectively suppressed, compared with that of microPCMs without Ag. Thus, the encapsulation of TD with silver-coated MUF shell developed by this work can be an effective method to prepare the microPCMs with enhanced thermal transfer performance and phase change properties.

Keywords

phase change materials / microcapsule / 1-tetradecanol / silver / metal coating