Recyclable Solid-Solid Phase Change Materials with Superior Latent Heat via Reversible Anhydride-Alcohol Crosslinking for Efficient Thermal Storage.

Solid-solid phase change materials (SSPCMs) with crosslinked polymer structures have received sustained interest due to their remarkable shape stability, enabling their application independently without the need for encapsulation or supporting materials. However, the crosslinking structure also compromises their latent heat and poses challenges to their recyclability. Herein, a novel strategy harnessing the internal-catalyzed reversible anhydride-alcohol crosslinking reaction to fabricate SSPCMs with superior latent heat and exceptional dual recyclability is presented. Easily accessible anhydride copolymers (e.g., propylene-maleic anhydride alternating copolymers), provide abundant reactive anhydride sites within the polymer matrix; polyethylene glycol serves as both the grafted phase change component and the crosslinker. The resulting SSPCMs attain a peak latent heat value of 156.8 J g-1 which surpasses all other reported recyclable crosslinked SSPCMs. The materials also exhibit certain flexibility and a tunable tensile strength ranging from 6.6 to 11.0 MPa. Beyond that, leveraging the reversible anhydride-alcohol crosslinks, the SSPCMs demonstrate dual recyclability through bond-exchange remolding and reversible-dissociation-enabled dissolving-recrosslinking without any reactive chemicals. Furthermore, by integrating solar-thermal conversion fillers like polydopamine nanoparticles, the potential of the system in efficient conversion, storage, and release of solar energy is highlighted.

Dicarbonyl-tuned microstructures of hierarchical porous carbons derived from coal-tar pitch for supercapacitor electrodes.

A simple and effective template-free method to prepare hierarchical porous carbons (HPCs) has been developed by using low-cost coal-tar pitch as a starting material, anhydrous aluminum chloride as the Friedel-Crafts catalyst, and oxalyl chloride as the cross-linking agent. By a simple controllable Friedel-Crafts reaction, diketone-functionalized coal-tar pitch as the hierarchical porous coal-tar pitch precursor was obtained via a one-step carbonization to provide a well-developed micro-mesoporous network. Nitrogen adsorption and desorption measurements showed that the surface area, pore volume, pore size and pore size distributions of the resulting carbon materials was dependent on the usage of the cross-linking agent. The as-fabricated HPCs have a large Brunauer-Emmett-Teller specific surface area of 1394.6 m2 g-1 and exhibit an excellent electrochemical performance with the highest specific capacitance of 317 F g-1 at a current density of 1 A g-1 in a three-electrode system. A symmetric supercapacitor was fabricated from HPC-DK-1.0 in a two-electrode system, which exhibits a high specific capacitance of 276 F g-1 at a current density of 0.25 A g-1, a high rate capability and an excellent cycling stability with a capacitance retention of 92.9% after 10 000 cycles. The one-step carbonization method that produced HPCs for electrical double-layer capacitors represents a new approach for high-performance energy storage.

Hierarchical porous carbon derived from carboxylated coal-tar pitch for electrical double-layer capacitors.

Hierarchical porous carbons have been synthesized using amphiphilic carboxylated coal-tar pitch as a precursor via a simple KOH activation process. Amphiphilic carboxylated coal-tar pitch has a high content of hydrophilic carboxyl groups that enable it to be easily wetted in KOH solution and that facilitate the activation process. In the present study, the effect of the activation agent to precursor ratio on the porosity and the specific surface area was studied by nitrogen adsorption-desorption. A maximum specific surface area of 2669.1 m2 g-1 was achieved with a KOH to carboxylated pitch ratio of three and this produced a structure with micropores/mesopores. Among the various hierarchical porous carbons, the sample prepared with an activation agent to precursor ratio of two exhibited the best electrochemical performance as an electrode for an electrical double-layer capacitor in a 6 M KOH electrolyte. The specific capacitance of the sample was 286 F g-1 at a current density of 2 A g-1 and it had a capacitance-retention ratio of 93.9%, even after 10 000 cycles. Thus, hierarchical porous carbons derived from amphiphilic-carboxylated coal-tar pitch represent a promising electrode material for electrical double-layer capacitors.

Amphiphilic tertiary amine N-oxides: a mediated radical emulsion polymerization with non-formation of alkoxyamine dormant chains.

Octadecylamine ethoxylate (EO = 5) N-oxides (AO-1805) were presented which are one kind of interfacial tertiary amine N-oxides that differ from TEMPO derivatives. This method took the advantage of amphiphilic alkyldiethoxylated amine oxide to form micelles, and had novel "living" characteristics based on the non-formation of dormant chains.