An increase in production of commercial products containing graphene-family nanomaterials (GFNs) has led to concern over their release into the environment. The fate and potential ecotoxicological effects of GFNs in the environment are currently unclear, partially due to the limited analytical methods for GFN measurements. In this review, the unique properties of GFNs that are useful for their detection and quantification are discussed. The capacity of several classes of techniques to identify and/or quantify GFNs in different environmental matrices (water, soil, sediment, and organisms), after environmental transformations, and after release from a polymer matrix of a product is evaluated. Extraction and strategies to combine methods for more accurate discrimination of GFNs from environmental interferences as well as from other carbonaceous nanomaterials are recommended. Overall, a comprehensive review of the techniques available to detect and quantify GFNs are systematically presented to inform the state of the science, guide researchers in their selection of the best technique for the system under investigation, and enable further development of GFN metrology in environmental matrices. Two case studies are described to provide practical examples of choosing which techniques to utilize for detection or quantification of GFNs in specific scenarios. Because the available quantitative techniques are somewhat limited, more research is required to distinguish GFNs from other carbonaceous materials and improve the accuracy and detection limits of GFNs at more environmentally relevant concentrations.

The structure of Langmuir monolayers containing either a lipidated poly(ethylene glycol) (PEG-lipid) or a lipidated peptide (peptide-amphiphile) or a binary mixture of both was studied using neutron reflectivity. The PEG portion of the PEG-lipid extends into the water, forming dense polymer “brushes”. The PEG volume fraction profiles and the brush height were evaluated from the reflectivity curves for monolayers containing PEG-lipids with PEG molecular masses of 120, 750, 2000, and 5000 Da at various grafting densities. At relatively low surface densities, the segmental concentration profile for DSPE-PEG5000 (1,2-distearoyl-sn-glycero-3-phosphoethanolamine-N-[(ethylene glycol) n ], DSPE) and DSPE-PEG2000 was well-described by the parabolic profile predicted by the analytical self-consistent mean field theory. An increase in the surface density produced “flattening” of the profile, which became more pronounced as the chain length decreased. The dependence of the brush height on the surface density and the chain length was in close agreement with the power laws predicted by the self-consistent mean field and the scaling theories. Unlike the flexible PEG chains, the peptide-amphiphile that was used in this study has a stiff conformation. The headgroup is oriented perpendicular to the air−water interface, and this configuration is nearly unaffected by changes in the surface density. Incorporation of the peptide-amphiphile into a PEG-lipid monolayer results in perturbation of the brush structure, due to the enhanced configuration constraints. These studies enable us to gauge how the tethered peptide in the monolayer can be exposed or masked when mixed with tethered PEG chains.

Bicontinuous porous structures through colloidal assembly realized by non-equilibrium process is crucial to various applications, including water treatment, catalysis and energy storage. However, as non-equilibrium structures are process-dependent, it is very challenging to simultaneously achieve reversibility, reproducibility, scalability, and tunability over material structures and properties. Here, a novel solvent segregation driven gel (SeedGel) is proposed and demonstrated to arrest bicontinuous structures with excellent thermal structural reversibility and reproducibility, tunable domain size, adjustable gel transition temperature, and amazing optical properties. It is achieved by trapping nanoparticles into one of the solvent domains upon the phase separation of the binary solvent. Due to the universality of the solvent driven particle phase separation, SeedGel is thus potentially a generic method for a wide range of colloidal systems.