Porous materials continue to establish critically important roles in applications extending from greenhouse gas capture to thermal superinsulation. Their effective structural control by an array of templating and template-free approaches imparts remarkable properties that are unattainable in the bulk. However, current preparative techniques frequently employ multiple, intricate steps that preclude scalability. Thus, there remains a need to reconcile this trade-off between structural control and procedural simplicity. Herein, a "freeze-burn" process is introduced as a rapid, robust strategy to fabricate porous carbon networks using polymer-templated rapid thermal annealing. Reduced graphene oxide is selected as the model material, templated by a polystyrene/poly(vinyl methyl ether) blend, to generate macropores on the size of phase separation, with the aim of understanding the impact of polymer mobility on templated morphologies. Without changing the template composition or processing conditions, we demonstrate applicability of freeze-burn to other carbon materials, such as graphene oxide, carbon black, carbon nanopowder, and multiwalled carbon nanotubes. This sequential templating and template degradation can be completed in one step in less than 10 min, making freeze-burn an energy-and time-efficient procedure. This work will serve as a powerful platform for the rapid templating of hard materials and will inspire simple, scalable approaches for creating porous structures.

The challenges faced with current fluorescence imaging agents have motivated us to study two nanostructures based on a hydrophobic dye, 6H-pyrrolo[3,2-b:4,5-b’]bis [1,4]benzothiazine (TRPZ). TRPZ is a heteroacene with a rigid, pi-conjugated structure, multiple reactive sites, and unique spectroscopic properties. Here we coupled TRPZ to a tert-butyl carbamate (BOC) protected 2,2-bis(hydroxymethyl)propanoic acid (bisMPA) dendron via azide-alkyne Huisgen cycloaddition. Deprotection of the protected amine groups on the dendron afforded a cationic terminated amphiphile, TRPZ-bisMPA. TRPZ-bisMPA was nanoprecipitated into water to obtain nanoparticles (NPs) with a hydrodynamic radius that was <150 nm. For comparison, TRPZ-PG was encapsulated in pluronic-F127 (Mw = 12 kD), a polymer surfactant to afford NPs almost twice as large as those formed by TRPZ-bisMPA. Size and stability studies confirm the suitability of the TRPZ-bisMPA NPs for biomedical applications. The photophysical properties of the TRPZ-bisMPA NPs show a quantum yield of 49%, a Stokes shift of 201 nm (0.72 eV) and a lifetime of 6.3 ns in water. Further evidence was provided by cell viability and cellular uptake studies confirming the low cytotoxicity of TRPZ-bisMPA NPs and their potential in bioimaging.

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