Steven Nutt

Bio: Steven Nutt is an academic researcher from University of Southern California. The author has contributed to research in topics: Epoxy & Composite number. The author has an hindex of 56, co-authored 290 publications receiving 13613 citations. Previous affiliations of Steven Nutt include Brown University & National Institute of Standards and Technology.

A Thermally Re-mendable Cross-Linked Polymeric Material

Abstract: We have developed a transparent organic polymeric material that can repeatedly mend or "re-mend" itself under mild conditions. The material is a tough solid at room temperature and below with mechanical properties equaling those of commercial epoxy resins. At temperatures above 120 degrees C, approximately 30% (as determined by solid-state nuclear magnetic resonance spectroscopy) of "intermonomer" linkages disconnect but then reconnect upon cooling, This process is fully reversible and can be used to restore a fractured part of the polymer multiple times, and it does not require additional ingredients such as a catalyst, additional monomer, or special surface treatment of the fractured interface.

Covalent polymer functionalization of graphene nanosheets and mechanical properties of composites

Abstract: For developing high performance graphene-based nanocomposites, dispersal of graphene nanosheets in polymer hosts and precise interface control are challenging due to their strong interlayer cohesive energy and surface inertia. Here we report an efficient method to functionalize graphene nanosheets. The initiator molecules were covalently bonded to the graphene surface via a diazonium addition and the succeeding atom transfer radical polymerization linked polystyrene chains (82 wt% grafting efficiency) to the graphene nanosheets. The prominent confinement effect arising from nanosheets resulted in a 15 °C increase in the glass transition temperature of polystyrene compared to the pure polymer. The resulting polystyrene nanocomposites with 0.9 wt% graphene nanosheets revealed around 70% and 57% increases in tensile strength and Young's modulus. The protocol is believed to offer possibilities for optimizing the processing properties and interface structure of graphene-polymer nanocomposites.

New Thermally Remendable Highly Cross-Linked Polymeric Materials

Abstract: Two new remendable highly cross-linked polymers, 2ME4F and 2MEP4F, were prepared without solvent. Solid-state NMR (nuclear magnetic resonance) was used to study the thermal reversibility of Diels−Alder (DA) cross-linking, and it was found that DA connections and disconnections of both polymers are thermally reversible. Differential scanning calorimeter and dynamical mechanical analysis were applied to study thermal and mechanical properties of these materials, and it is found that the glass transition temperature (Tg) of 2ME4F is about 30−40 °C and that of 2MEP4F is about 80 °C. A qualitative study of the healing efficiency of 2MEP4F showed that cracks can be healed effectively with a simple thermal healing procedure. This process can be repeated to heal cracks multiple times.

Single-layer graphene nanosheets with controlled grafting of polymer chains

Abstract: Single-layer graphene nanosheets (SLGNs) are prepared by reduction of well-exfoliated graphite oxide aided by a surfactant (sodium dodecylbenzene sulfonate, SDBS). Grafting density and polystyrene (PS) chain lengths are controlled by modulating the concentrations of diazonium compound and monomer during the grafting reaction of the initiator and the succeeding atomic transfer radical polymerization (ATRP). Atomic force microscopy (AFM), X-ray diffraction (XRD), Raman spectra and transmission electron microscopy (TEM) are used to confirm the single-layer structure of graphene sheets, covalent bonding at the interface, and distribution uniformity of grafting PS chains at the SLGN surface. Thermogravimetric analysis (TGA) is performed to assess the control of grafting density and chain length. PS chains grafted on the SLGN surface exhibited remarkably confined relaxation behavior. An increase in the glass transition temperature (Tg) of up to 18 °C is observed for high grafting density, low molecular weight polymer-grafted graphene samples. The low grafting density, high molecular weight sample shows an increase in Tg of ∼9 °C, which is attributed to superior heat conduction efficiency. The measured thermal conductivity for the PS composite film with 2.0 wt% SLGNs increase by a factor of 2.6 compared to that of the pure PS.

The Design and Analysis of Experiments

Abstract: THE DESIGN AND ANALYSIS OF EXPERIMENTS. By Oscar Kempthorne. New York, John Wiley and Sons, Inc., 1952. 631 pp. $8.50. This book by a teacher of statistics (as well as a consultant for \"experimenters\") is a comprehensive study of the philosophical background for the statistical design of experiment. It is necessary to have some facility with algebraic notation and manipulation to be able to use the volume intelligently. The problems are presented from the theoretical point of view, without such practical examples as would be helpful for those not acquainted with mathematics. The mathematical justification for the techniques is given. As a somewhat advanced treatment of the design and analysis of experiments, this volume will be interesting and helpful for many who approach statistics theoretically as well as practically. With emphasis on the \"why,\" and with description given broadly, the author relates the subject matter to the general theory of statistics and to the general problem of experimental inference. MARGARET J. ROBERTSON

The chemistry of graphene oxide

Abstract: The chemistry of graphene oxide is discussed in this critical review Particular emphasis is directed toward the synthesis of graphene oxide, as well as its structure Graphene oxide as a substrate for a variety of chemical transformations, including its reduction to graphene-like materials, is also discussed This review will be of value to synthetic chemists interested in this emerging field of materials science, as well as those investigating applications of graphene who would find a more thorough treatment of the chemistry of graphene oxide useful in understanding the scope and limitations of current approaches which utilize this material (91 references)

Graphene and Graphene Oxide: Synthesis, Properties, and Applications

Abstract: There is intense interest in graphene in fields such as physics, chemistry, and materials science, among others. Interest in graphene's exceptional physical properties, chemical tunability, and potential for applications has generated thousands of publications and an accelerating pace of research, making review of such research timely. Here is an overview of the synthesis, properties, and applications of graphene and related materials (primarily, graphite oxide and its colloidal suspensions and materials made from them), from a materials science perspective.

Additive manufacturing (3D printing): A review of materials, methods, applications and challenges

Abstract: Freedom of design, mass customisation, waste minimisation and the ability to manufacture complex structures, as well as fast prototyping, are the main benefits of additive manufacturing (AM) or 3D printing. A comprehensive review of the main 3D printing methods, materials and their development in trending applications was carried out. In particular, the revolutionary applications of AM in biomedical, aerospace, buildings and protective structures were discussed. The current state of materials development, including metal alloys, polymer composites, ceramics and concrete, was presented. In addition, this paper discussed the main processing challenges with void formation, anisotropic behaviour, the limitation of computer design and layer-by-layer appearance. Overall, this paper gives an overview of 3D printing, including a survey on its benefits and drawbacks as a benchmark for future research and development.