Encapsulation of Phase Change Materials via Interfacial Miniemulsion Polymerization for High Thermal Energy Storage Density

Abstract

Phase change material (PCM) capsules have potential applications as a thermal management material in energy-efficient buildings. It is desirable for PCM capsules to have high core-loading and sub-micrometer particle size. Herein, it is reported that interfacial reversible addition-fragmentation chain transfer (RAFT) miniemulsion polymerization can be a convenient method to synthesize high PCM loading polymeric capsule latex. It is found that increasing particle size should be helpful to obtain well-defined capsules of high PCM loading but post-addition of surfactant should be carried out to remain the colloidal stability during polymerization. In the case of high PCM loading, a limiting conversion is observed. Increasing crosslinker (DVB) level up to 20 wt% based on monomers can increase the limiting conversion up to 94%. The well-defined paraffin capsules of 365 nm in diameter is synthesized with 67 wt% PCM loading. The paraffin capsules have a crystallization/melting heat around 105 J g −1 . Replacing paraffin with pure n-octadecane, the crystallization/melting heat is increased up to 144 J g −1 .

Opinions on Fabrication of Phase Change Microcapsule Slurry and Its Application in Electronic Cooling

“…The interfacial polymerization is similar to in situ polymerization where the polymerization occurs at the interface of core material emulsion. The formation of a shell is caused by the polymerization of reactants inside and outside the interface (Zhao and Luo, 2022). Polymerization methods have the advantages of rapid reaction, mild conditions, and simple operation.…”

“…Based on microfluidic chips, micro/nanoscale single and double emulsions with perfect sphericity can be prepared, and the capsule size can be controlled easily by changing the flow rate of phases, which has drawn extensive attention. Axisymmetric microfluidic chips, such as flow focusing (Srinivasaraonaik et al, 2020) and interfacial polymerization (Zhao and Luo, 2022), respectively, (B) coacervation (Malekipirbazari et al, 2014), (C) microfluidic EPCM production (I: glass slide, II: dispensing needles, III: inner capillary, IV: outer capillary) (Hao et al, 2022). (Akamatsu et al, 2019) and coflowing (Fu et al, 2014) are usually used for preparing EPCM.…”

“…FIGURE 1 | Encapsulation methods: (A) polymerization, (a1) and (a2) are EPCM produced by in situ polymerization(Srinivasaraonaik et al, 2020) and interfacial polymerization(Zhao and Luo, 2022), respectively, (B) coacervation(Malekipirbazari et al, 2014), (C) microfluidic EPCM production (I: glass slide, II: dispensing needles, III: inner capillary, IV: outer capillary)(Hao et al, 2022).…”

Self-catalyzed synthesis of a nano-capsule and its application as a heterogeneous RCMP catalyst and nano-reactor

“…Because the shell permeability mainly depended on the molecular size but not the molecular polarity, we were also able to use multiple monomers with different polarities altogether and entrap a mixed-polar multi-functional random copolymer. Although the present paper focuses on the proof of principle, the potential applications of polymers entrapped in a nano-capsule (nano-reactor) would include non-leaking polymer adsorbents and encapsulation of phase change materials (PCM) to prevent PCM from leaking and modulate the phase change temperature during the phase change processes, 64–66 for example. Fig.…”