posted on 2021-11-11, 17:36authored byYunchong Zhang, Feifei Wang, Joost Duvigneau, Yan Wang, Bijia Wang, Xueling Feng, Zhiping Mao, G. Julius Vancso, Xiaofeng Sui
Hydrated
salts (salt hydrates) are highly promising low-temperature
phase change materials (PCMs) due to their high cohesive energy density
and low cost. However, they exhibit phase separation, liquid leakage,
and inherent supercooling, which hinder their applications in sustainable
building technology. Here, we describe the design of a highly stable
emulsion gel system (EmulGels) that exhibits nonflammable and shape-memory
characteristics. Oleophilic paraffin and hydrophilic hydrated salts,
both of which are excellent PCMs typically existing in separate phases,
are combined harmoniously in a gel by a templating water-in-oil Pickering
emulsion. Latent heat values of the prepared EmulGels were up to 213.2
J/g (eicosane/disodium hydrogen phosphate dodecahydrate = 1:3). No
leakage of eicosane was noticed after heating the EmulGels at 60 °C
for 30 min, and the latent heat value remained almost unchanged following
500 thermal cycles. The EmulGel was specifically designed to enable
dual-phase crosslinking, which effectively enhanced its shape stability,
slowed down loss of water of crystallization in hydrated salts, and
decreased the degree of supercooling. Nonflammable characteristic
typically found in hydrated salts was also exhibited by the EmulGel,
in combination with good mechanical properties. The materials characteristics
make EmulGels ideal candidates to serve as building construction interlayers
for effective thermal building management.