Imine-linked micron-network polymers with high polyethylene glycol uptake for shaped-stabilized phase change materials

Micron-network polymers, NP-A and NP-B with high free porosities (up to 89.6%) were synthesized via imine condensation between tetra-arm aldehyde and aromatic diamines. In the meantime, novel polyethylene glycol (PEG)@network polymer shape-stabilized phase change materials (ssPCMs) were prepared by introducing PEG into the network polymers. The structure and morphology of the network polymers and the ssPCMs were systematically studied by SEM, FT-IR, solid-state C-13 NMR, XRD and TGA. The experimental results showed that the network polymers with similar C-O-C functional groups to PEG exhibited good interface combination with PEG-6000 in ssPCMs. A comparison of NP-A and NP-B indicated that a smaller interstitial space induced much stronger interactions, which could promote the adsorption capacity of PEG in network polymers. With high free porosities and large enough interstitial space, the micron-network polymers exhibited good adsorption capacity for PEG (up to 85 wt%) without leakage even above its melting point. The PEG in the micron-network kept its high crystallinity that guaranteed the latent heat (up to 164.9 J g(-1)) of the ssPCMs close to the calculated values (168.9 J g(-1)). This work opens up alternative routes to prepare ssPCMs with high energy storage density for latent heat energy storage (LTES).