Functional nanomaterials for energy and sustainability

In view of the continuous decline in fossil fuel reserves, at a time when energy demands are steadily increasing, a diverse range of emerging nanotechnologies promise to secure modern solutions to the prehistoric energy problem. Each one of those distinct approaches capitalizes on different principles, concepts and methodologies to address different application requirements, but their common objective is to open a window to a sustainable energy future. Consequently, they all deserve substantial (though not necessarily equal) consideration from the scientific and engineering community. In this review we present bottom-up strategies that show great promise for the development of a new generation of advanced materials for energy applications without compromising the public safety or the environment

Trivial and Non-Trivial Supramolecular Assemblies Based on Nafion

We demonstrate that Nafion, a perfluorosulfonic acid ionomer, undergoes synergistic mixing with non-ionic diblock copolymers in selective solvents. A range of experimental techniques (Quartz Crystal Microbalance, Dynamic Light Scattering, optical microscopy, TEM and SEM) was employed to gain insights on the evolution of ionomer–copolymer supramolecular assemblies. Depending on the copolymer architecture and the type of the suspension medium, spherical nanoparticles, micron-long tubular conformations or vesicular structures are formed. Those morphologies are dictated by localized interactions arising from Nafion's amphiphilicity. The effect has implications on the preparation of the technologically important ion conducting membranes

Thermoreversible gelation in poly(ethylene oxide)/carbon black hybrid melts

The study focuses on the structure and viscoelasticity of poly(ethylene oxide)/carbon black fluids. The hybrids when subjected to extreme thermal annealing (at temperatures far above the melting point of the matrix) exhibit a 3-4 orders of magnitude increase in viscosity. Surprisingly, the effect is reversible and the viscosity reverts back to its initial value upon subsequent cooling. This rather unique sol-gel transition in terms of strength, steepness and thermal reversibility points to major structural rearrangements via extensive particle clustering, in agreement with microscopy observations. In related systems it was found that when matrix-particle electrostatic interactions are present the gelation is essentially diminished

Nanoclay-Directed Structure and Morphology in PVDF Electrospun Membranes

The incorporation of organically modified Lucentite nanoclay dramatically modifies the structure and morphology of the PVDF electrospun fibers. In a molecular level, the nanoclay preferentially stabilizes the all-trans conformation of the polymer chain, promoting an α to β transformation of the crystalline phase. The piezoelectric properties of the β-phase carry great promise for energy harvest applications. At a larger scale, the nanoclay facilitates the formation of highly uniform, bead-free fibers. Such an effect can be attributed to the enhanced conductivity and viscoelasticity of the PVDF-clay suspension. The homogenous distribution of the directionally aligned nanoclays imparts advanced mechanical properties to the nanofibers

Graphene quantumdots: In the crossroad of graphene, quantum dots and carbogenic nanoparticles

The scientific and technological importance of graphene quantum dots (GQDs) is directly related to their nanoscopic nature that endows remarkable photo-physical properties and colloidal stability in a variety of solvents. GQDs combine characteristics arising from their graphitic structure, their carbogenic origin and their quantum nature. They are considered as the environmentally benign alternatives of heavy metal based quantum dots, given that not only are they synthesized following green strategies, but they also exhibit minimal toxicity. GQDs are systematically explored in printing, energy harvesting, bioimaging, catalysis, optoelectronics and sensing applications

Carbon Dots for Forensic Applications: A Critical Review

Owing to their superior fluorescence performance, inexpensive synthesis and nontoxic nature, carbon dots (C-dots) are systematically explored in a variety of applications; in this review, we outline and critically discuss recent trends with respect to their potential exploitation in criminal investigation, forensic toxicology and anti-counterfeit interventions. Capitalising on their colour-tuneable behaviour (in the sense that they adopt different colours with respect to the incident radiation), C-dot-based compositions are ideal for the visual enhancement of latent fingerprints, affording improved contrast against multicoloured and patterned backgrounds. As highly sensitive and highly selective optical nanoprobes, C-dots show excellent analytical performance in detecting biological compounds, drugs, explosives, heavy metals and poisonous reactants. In addition, benefiting from their versatile structural and chemical composition, C-dots can be incorporated into ink and polymeric formulations capable of functioning as a new generation of cost-effective barcodes and security nanotags for object authentication and anti-counterfeit applications. Translating these encouraging research outcomes into real-life innovations with significant social and economic impact requires an open, multidisciplinary approach and a close synergy between materials scientists, biologists, forensic investigators and digital engineers

Nanoclay-Directed Structure and Morphology in PVDF Electrospun Membranes

The incorporation of organically modified Lucentite nanoclay dramatically modifies the structure and morphology of the PVDF electrospun fibers. In a molecular level, the nanoclay preferentially stabilizes the all-trans conformation of the polymer chain, promoting an α to β transformation of the crystalline phase. The piezoelectric properties of the β-phase carry great promise for energy harvest applications. At a larger scale, the nanoclay facilitates the formation of highly uniform, bead-free fibers. Such an effect can be attributed to the enhanced conductivity and viscoelasticity of the PVDF-clay suspension. The homogenous distribution of the directionally aligned nanoclays imparts advanced mechanical properties to the nanofibers

Carbogenically coated silica nanoparticles and their forensic applications

Carbogenically coated silica nanoparticles (C-SiO2) exhibit color-tunability and carry great promise for two important forensic applications. First, the C-SiO2 nanopowders are ideal for fingerprint development, yielding strong contrast against multicoloured and patterned backgrounds. Second, spontaneous nanoparticle aggregation leads to non-duplicable, inexpensive nanotags that can support sustainable technologies to combat counterfeiting

Novel hydrogels containing Nafion and poly (ethylene oxide) based block copolymers

We present a novel family of biocompatible hydrogels containing Nafion and poly(ethylene oxide) based block copolymers. In aqueous environment, thermodynamically stable ionomer-copolymer complexes are formed, as evident by light scattering and quartz crystal microbalance experiments. Moreover, incorporation of Nafion dramatically modifies the phase behaviour and the rheological properties of copolymer hydrogels. The hybrid systems not only undergo sharp and thermally reversible sol-gel transitions below the body temperature, thus retaining their injectable nature, but they also generate mechanically robust hydrogels. Moreover, ibuprofen was continuously released over a period of 26 days for the Nafion/Pluronic hydrogel, compared to only 3 days for the Nafion-free system. The hybrid gels are promising candidates for 3D-bioprinting and controlled drug release applications

Carbon-Based Nanomaterials as Novel Nanosensors [Editorial]

In recent years, nanosensor technology has experienced a rapid development because of the extensive scientific efforts in understanding of nanoscale phenomena and achieving innovative nanofabrication techniques. Carbon-based nanomaterials (CBNs), such as fullerenes, graphene, nanodiamonds, carbon nanotubes, and carbon nanodots, have recently gained considerable attention among scientific communities due to their unique chemical and physical properties. Thanks to intensive research efforts, the CBNs have found their place in a wide range of applications. These CBNs stand out as novel nanosensors due to their supreme performance in detecting heavy metal ions, gas molecules, food additives, antibodies, and toxic pesticides, as well as reporters for bioimaging. This special issue, to be published in 2017, addresses recent progress in the synthesis, characterization, structure-property relationships and applications of CBNs as novel nanosensors. We are confident that the accrual of these contributions will facilitate the applications of CBNs as innovative nanosensors in meeting the urgent needs for environmental monitoring, food safety control, healthcare, homeland security, and so forth. We have selected five papers, representing four different frontiers of this topic: graphene, silver nanoparticles, carbon nanotubes, and carbon nanodots