Using UV–vis spectrum to investigate the phase transition process of PMMA–SiO 2@paraffin microcapsules with copper-chelating as the ion probe

Abstract

The technique of UV–vis spectrum can offer the ability for characterizing phase transition process and structure characteristics of phase change materials. Experiment testing absorbance change of UV–vis spectrum has been conducted on the phase transition process of PMMA–SiO 2@paraffin microcapsules with copper-chelating as the ion probe. The phase transition process has successfully measured that there was little change in absorbance of UV–vis spectrum, which should be caused by the heat absorbance of the phase change materials. After the phase change was completed, the spectrum absorbance of microcapsules had a sudden drop. The special UV–vis spectrum of PMMA–SiO 2@paraffin microcapsules should be caused by the changes of charge distribution or molecular interaction of ion probe Cu(II) chelating in microcapsules. The UV–vis spectrum can be used to study the phase change process of the Cu(II)–PMMA–SiO 2@paraffin microcapsules as well as other similar configurations with Cu(II) chelating as the ion probe.