Carbon nanotubes and graphene are some of the most intensively explored carbon allotropes in materials science. This interest mainly resides in their unique properties with electrical conductivities as high as 10 4 S cm À1 , thermal conductivities as high as 5000 W m À1 K and superior mechanical properties with elastic moduli on the order of 1 TPa for both of them. The possibility to translate the individual properties of these monodimensional (e.g. carbon nanotubes) and bidimensional (e.g. graphene) building units into twodimensional free-standing thick and thin films has paved the way for using these allotropes in a number of applications (including photocatalysis, electrochemistry, electronics and optoelectronics, among others) as well as for the preparation of biological and chemical sensors. More recently and while recognizing the tremendous interest of these two-dimensional structures, researchers are noticing that the performance of certain devices can experience a significant enhancement by the use of three-dimensional architectures and/ or aerogels because of the increase of active material per projected area. This is obviously the case as long as the nanometre-sized building units remain accessible so that the concept of hierarchical three-dimensional organization is critical to guarantee the mass transport and, as consequence, performance enhancement.Thus, this review aims to describe the different synthetic processes used for preparation of these threedimensional architectures and/or aerogels containing either any or both allotropes, and the different fields of application in which the particular structure of these materials provided a significant enhancement in the efficacy as compared to their two-dimensional analogues or even opened the path to novel applications. The unprecedented compilation of information from both CNT-and graphene-based three-dimensional architectures and/or aerogels in a single revision is also of interest because it allows a straightforward comparison between the particular features provided by each allotrope.

The aim of this review is to provide an exposition of some of the most recent applications of deep-eutectic solvents (DESs) in the synthesis of polymers and related materials. We consider that there is plenty of room for the development of fundamental research in the field of DESs because their compositional flexibility makes the number of DESs susceptible of preparation unlimited and so do the range of properties that DESs can attain. Ultimately, these properties can be transferred into the resulting materials in terms of both tailored morphologies and compositions. Thus, interesting applications can be easily envisaged, especially in those fields in which the preparation of high-tech products via low cost processes is critical. We hope that the preliminary work surveyed in this review will encourage scientists to explore the promising perspectives offered by DESs.

This review aims to demonstrate the capability of the ice-segregation-induced self-assembly (ISISA) process for the preparation of materials with highly sophisticated structures (e.g., hierarchical materials exhibiting organization at different scale levels). Cryogenic processes (consisting of the freezing, storage in the frozen state for a definite time, and defrosting of low - or high-molecular-weight precursors, as well as colloid systems, as either a water solution or suspension, or forming a hydrogel) have been widely used for the scaffolds preparation. However, the recent success in the control of the morphology (e.g., by unidirectional freezing in nitrogen liquid) and the possibility to extend the compositional nature of the resulting materials has recently attracted much attention to the ISISA process. Besides, this review aims to exemplify how the aqueous nature of the ISISA process allows for the in-situ incorporation of biological entities which provides not only hierarchy but also functionality to the resulting materials. The combination of hierarchy and functionality is characteristic of biological structures and must make these “smart” materials highly suitable in biotechnology and biomedicine. Thus, interesting examples of biocatalytic materials (for organic synthesis and fuel cell technologies) and biosensors, and scaffolds exhibiting enhanced functional (in terms of both biocompatibility and biodegradability) and mechanical performance, are reviewed in this work.

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It has long been appreciated that both temperature and density play roles in determining the extremely super-Arrhenius, low-temperature behavior of the viscosity and long α-relaxation times that characterize fragile supercooled liquids. But what has not been generally appreciated, and what we believe we have established (by focusing on a model-free analysis in terms of temperature and density, rather than upon temperature and pressure) is that over the range of densities and temperatures spanned by the experiments carried out at 1 atm pressure, temperature is the dominant control variable. This information is essential input to the formulation of a theory or model of the long-time dynamics of low-temperature fragile liquids, and it suggests a focus on activated dynamics rather than on free volume. This work indicates that, except possibly at very high densities (very high pressures), the glass transition is not a result of congestion due to a lack of free volume.

This work describes how the preparation of deep eutectic solvents (DES) in its pure state can be accomplished through a simple approach based on the freeze-drying of aqueous solutions of the individual counterparts of DES. DES in its pure state obtained via freeze-drying are studied by (1)H NMR, which reveals the formation of halide ion-hydrogen-bond-donor supramolecular complexes (characteristic of DES), and by cryo-etch-SEM, which provides insight about the capability of aqueous solutions of DES to be segregated in DES and ice upon freezing. The paper also explores the suitability of the freeze-drying approach to incorporate organic self-assemblies (in particular, liposomes of ca. 200 nm) in DES with full preservation of their self-assembled structure. This is not a trivial issue given that amphiphilic molecules tend to be readily dissolved (hence, disassembled) in DES. The strategy proposed in this work is based on the freeze-drying of aqueous solutions containing the individual counterparts of DES and the preformed liposomes (also known as large unilamellar vesicles or LUV). The simplicity of the method should also make it suitable for the incorporation of different self-assembled structures (such other types of vesicles and micelles) in DES in its pure state.

There is a striking disparity between the heart-shaped structure of human serum albumin (HSA) observed in single crystals and the elongated ellipsoid model used for decades to interpret the protein solution hydrodynamics at neutral pH. These two contrasting views could be reconciled if the protein were flexible enough to change its conformation in solution from that found in the crystal. To investigate this possibility we recorded the rotational motions in real time of an erythrosin-bovine serum albumin complex (Er-BSA) over an extended time range, using phosphorescence depolarization techniques. These measurements are consistent with the absence of independent motions of large protein segments in solution, in the time range from nanoseconds to fractions of milliseconds, and give a single rotational correlation time phi(BSA, 1 cP, 20 degrees C) = 40 +/- 2 ns. In addition, we report a detailed analysis of the protein hydrodynamics based on two bead-modeling methods. In the first, BSA was modeled as a triangular prismatic shell with optimized dimensions of 84 x 84 x 84 x 31.5 A, whereas in the second, the atomic-level structure of HSA obtained from crystallographic data was used to build a much more refined rough-shell model. In both cases, the predicted and experimental rotational diffusion rate and other hydrodynamic parameters were in good agreement. Therefore, the overall conformation in neutral solution of BSA, as of HSA, should be rigid, in the sense indicated above, and very similar to the heart-shaped structure observed in HSA crystals.

Poly(vinyl alcohol) (PVA) scaffolds are prepared by a cryogenic process that consists of the unidirectional freezing of a PVA solution. The scaffolds exhibit a microchanneled structure, the morphology of which (in terms of pore diameter, surface area, and thickness of matter accumulated between adjacent microchannels) can be finely tailored by the averaged molecular weight of PVA, the PVA concentration in the solution, and the freezing rate of the PVA solution. The resulting PVA scaffolds are suitable substrates for drug‐delivery purposes, the drug release being controlled (from tens of minutes up to several days) by the morphology of the microchanneled structure. In vitro experiments reveal the efficiency of PVA scaffolds for controlling the release of ciprofloxacin into a bacteria culture medium.