Graphene Oxide: Surface Activity and Two‐Dimensional Assembly

Kim, Franklin; Cote, Laura J.; Huang, Jiaxing

doi:10.1002/adma.200903932

Cited by 639 publications

(486 citation statements)

References 41 publications

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“…GO exhibits a rough surface showing wrinkles 41,42 . It has been reported that during the drying process of GO, water exerts surface tension due to high affinity to GO oxidized domains 43 , inducing stresses during evaporation 44 , which force the soft sheets to fold and wrinkle 45,46 and/or can exacerbate the wrinkled structure 43 . In particular, in Figures 1E and 1F nanosheets edges of about 5 nm can be detected that correspond to the largest thickness observed in the sample.…”

Section: Go Characterizationmentioning

confidence: 99%

Formation of Cellulose Acetate–Graphene Oxide Nanocomposites by Supercritical CO₂ Assisted Phase Inversion

Baldino

Sarno

Cardea

et al. 2015

Ind. Eng. Chem. Res.

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(Stefano Cardea) Phone Number: +39089969365; msarno@unisa.it (Maria Sarno) Phone Number: +39089964057.KEYWORDS: Graphene oxide, Cellulose acetate, Nanocomposite, Supercritical CO 2 . ABSTRACTCellulose acetate (CA)/graphene oxide (GO) nanocomposite membranes were generated by an assisted phase inversion process, based on the use of SC-CO 2 as non-solvent, operating at 200 bar and 40 °C; loadings of GO up to 9% w/w were tested. The structures maintained the cellular morphology, characteristics of CA membranes, also at the highest GO loadings used, with a porosity of about 80%, but the presence of GO influenced the pore sizes, that ranged between about 9 and 16 µm. The starting GO and the nanocomposite structures were characterized by the combination of various techniques that evidences as Sulphur and Chlorinated impurities, that were present in the starting GO material, were completely eliminated by the interaction with SC-CO 2 during structures formation; moreover, a partial reduction of GO to graphene was also observed. . Compared to graphene, GO is heavily oxygenated and its basal plane carbon atoms are decorated with epoxide and hydroxyl groups and its edge atoms with carbonyl and carboxyl groups. Hence, GO is highly hydrophilic and the presence of these functional groups reduces interplanar forces, which can improve the interfacial interaction between GO and some polymers and, thus, the dispersion of GO in polymer matrices 2,3 . Many factors can affect the final properties and applications of GO/polymer nanocomposites 4 , among these: kind of GO used, its dispersion state in the polymeric matrix and interfacial interactions, the amount of wrinkling, its network structure in the matrix and its purity.Various attempts have been proposed in the literature to realize GO/polymers composite structures [5][6][7][8][9][10][11][12][13][14][15] . The processes proposed until now (i.e., phase inversion, casting, electrospinning) present several limitations; for example, residues of organic solvents of GO synthesis are typically found at the end of these processes, causing problems, in particular, for biomedical applications. Moreover, a homogeneous distribution of GO in the polymeric matrix is difficult to obtain, since the cohesive forces among GO layers tend to produce restacking. GO composites performance is strongly related to its level of exfoliation (i.e., separation of the layers). Exfoliated GO allows the largest interfacial contact with the polymer matrix, improving the properties of the composites. For this reason, several techniques have been implemented to increase the GO exfoliation degree. In particular, solvent-based exfoliation and thermal exfoliation techniques emerged as two preferred routes for this step [16][17][18][19] . [30][31][32][33] . Due to molecular size of CO 2 and its polarizability, it has the potential to pass through the solid porous layers 34 and, when supercritical conditions are reached, CO 2 diffusivity can favor layers expansion and exfoliation [31][32][33] . It is also possible to...

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Section: Go Characterizationmentioning

confidence: 99%

Formation of Cellulose Acetate–Graphene Oxide Nanocomposites by Supercritical CO₂ Assisted Phase Inversion

Baldino

Sarno

Cardea

et al. 2015

Ind. Eng. Chem. Res.

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“…Compared with the transfer of graphene film, the film‐formation of GO demonstrates to be more convenient and scale‐up, as well as no limit to substrates. Numerous approaches have been adopted to prepare GO films, including drop‐casting,52, 53 spin‐coating,54 vacuum filtration,5, 55 or other assembly processes56, 57, 58, 59 and so on.…”

Section: Properties and Preparationmentioning

confidence: 99%

Human‐Like Sensing and Reflexes of Graphene‐Based Films

et al. 2016

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Humans have numerous senses, wherein vision, hearing, smell, taste, and touch are considered as the five conventionally acknowledged senses. Triggered by light, sound, or other physical stimulations, the sensory organs of human body are excited, leading to the transformation of the afferent energy into neural activity. Also converting other signals into electronical signals, graphene‐based film shows its inherent advantages in responding to the tiny stimulations. In this review, the human‐like senses and reflexes of graphene‐based films are presented. The review starts with the brief discussions about the preparation and optimization of graphene‐based film, as where as its new progress in synthesis method, transfer operation, film‐formation technologies and optimization techniques. Various human‐like senses of graphene‐based film and their recent advancements are then summarized, including light‐sensitive devices, acoustic devices, gas sensors, biomolecules and wearable devices. Similar to the reflex action of humans, graphene‐based film also exhibits reflex when under thermal radiation and light actuation. Finally, the current challenges associated with human‐like applications are discussed to help guide the future research on graphene films. At last, the future opportunities lie in the new applicable human‐like senses and the integration of multiple senses that can raise a revolution in bionic devices.

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“…102 Pickering-type oil-in-water emulsions, so-called 'armored droplets,' formed upon adding an organic solvent to an aqueous solution of GO, while GO segregation to the air Àwater interface was studied by Langmuir ÀBlodgett techniques. 103,104 Langmuir ÀBlodgett films of single GO sheets (one carbon atom thick) were reduced to give CCG films with a resistance of 4 MO cm, similar to values obtained for multilayer CCG films. 103 The assembly properties of GO were controlled further by tuning the pH and platelet aspect ratio (thus, varying the amphiphilicity of the structures).…”

Section: Go At Interfacesmentioning

confidence: 99%

“…103,104 Langmuir ÀBlodgett films of single GO sheets (one carbon atom thick) were reduced to give CCG films with a resistance of 4 MO cm, similar to values obtained for multilayer CCG films. 103 The assembly properties of GO were controlled further by tuning the pH and platelet aspect ratio (thus, varying the amphiphilicity of the structures). [105][106][107] Graphene composites exploiting p-p interactions Exploiting p-p interactions between graphene and other aromatic molecules during synthesis can effectively organize materials that are otherwise not processable.…”

Section: Go At Interfacesmentioning

confidence: 99%

Nanoscale assembly into extended and continuous structures and hybrid materials

Emrick

Pentzer

2013

NPG Asia Mater

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Harnessing synthetic power to create novel materials with unique assembly properties is of fundamental interest for pushing the limits of molecular and macromolecular assembly, while further holding the potential for improving electronic and medical device performance. Controlling the assembly of aromatic molecules into nanostructures provides routes towards continuous and extended structures with performance that is improved markedly over that of their individual molecular components, opening possibilities for the formation of composites that have tailored interactions with other materials and thus improved applications. This review covers recent advances in the synthesis of conjugated materials, their controlled assembly into nanoscale architectures and implementation into devices. Specifically, we discuss the solution-based assembly of polythiophene into nanowire fibrils, the formation of columnar stacks of hexabenzocoronene liquid crystals and the preparation of functionalized solution processible graphene for nanocomposite formation.

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Graphene Oxide: Surface Activity and Two‐Dimensional Assembly

Cited by 639 publications

References 41 publications

Formation of Cellulose Acetate–Graphene Oxide Nanocomposites by Supercritical CO₂ Assisted Phase Inversion

Formation of Cellulose Acetate–Graphene Oxide Nanocomposites by Supercritical CO₂ Assisted Phase Inversion

Human‐Like Sensing and Reflexes of Graphene‐Based Films

Nanoscale assembly into extended and continuous structures and hybrid materials

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Graphene Oxide: Surface Activity and Two‐Dimensional Assembly

Cited by 639 publications

References 41 publications

Formation of Cellulose Acetate–Graphene Oxide Nanocomposites by Supercritical CO2 Assisted Phase Inversion

Formation of Cellulose Acetate–Graphene Oxide Nanocomposites by Supercritical CO2 Assisted Phase Inversion

Human‐Like Sensing and Reflexes of Graphene‐Based Films

Nanoscale assembly into extended and continuous structures and hybrid materials

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Product

Resources

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Formation of Cellulose Acetate–Graphene Oxide Nanocomposites by Supercritical CO₂ Assisted Phase Inversion

Formation of Cellulose Acetate–Graphene Oxide Nanocomposites by Supercritical CO₂ Assisted Phase Inversion