Encapsulation of stearic acid with different PMMA-hybrid shell materials for thermotropic materials. (15th May 2019)

• Record Type: Journal Article
• Authors: Şahan, Nurten; Nigon, Daniel; Mantell, Susan C.; Davidson, Jane H.; Paksoy, Halime
• Is Part Of: Solar energy. Volume 184(2019)
• Page Start: 466
• Page End: 476
• Publication Date: 2019-05-15
• Subjects: Thermal energy storage -- Phase change material -- Microencapsulation -- PMMA -- Stearic acid -- Thermotropic material; Solar energy -- Periodicals; Solar engines -- Periodicals; 621.47
• DOI: 10.1016/j.solener.2019.04.026
• Languages: English
• ISSNs: 0038-092X

Abstract

Highlights: Stearic acid was successfully encapsulated with hybrid shell materials. Influences using different co-monomers on morphologies and thermal properties were determined. Properties of encapsulated PCMs suitable for thermotropic materials were investigated. Abstract: In this study, we synthesized and characterized particles with a stearic acid (SA) core encapsulated in poly(methyl methacrylate) (PMMA) and four PMMA-hybrid shell materials. The objective was to create spherical particles with diameters of several hundred nanometers for use as the dispersed phase in thermotropic materials for overheat protection of polymer solar absorbers. Encapsulation was accomplished by emulsion polymerization. The composition, morphology and thermal properties of the encapsulated particles were characterized by scanning and transmission microscopy, Fourier transform infrared spectral analysis, digital scanning calorimetry and thermogravimetry. There were no chemical interactions between core and shell materials. The mean diameter and the thickness of the encapsulating shell varied over relatively narrow ranges of 110–360 nm, and 17–60 nm, respectively, depending on the functional groups of the shell. Based on published recommendations for size and shell thickness for thermotropic materials for overheat protection of polymer solar absorbers, particles encapsulated with polymethylmethacrylate-co-2-hydroxy-ethylacrylate (PMMA-HEA) shell and with polymethylmethacrylate-styrene (PMMA-S) shell are good candidates for further evaluation.