Additively Manufactured Silicone Polymer Composite with High Hydrogen Getter Content and Hydrogen Absorption Capacity.

Hydrogen getters consisting of 1,4-bis[phenylethynyl] benzene (DEB) and a carbon-supported palladium catalyst (Pd/C) have been used to mitigate the accumulation of unwanted hydrogen gas in a sealed system. Here, we report the formulation of a composite resin consisting of silicone polymer plus DEB-Pd/C as an active getter material and the additive manufacturing of silicone getter composites with a high getter content (up to 50 wt %). NMR and DSC studies suggest no reaction between the silicone polymer resin and DEB even at elevated curing temperatures (75 °C).

Interplay between Shelf Life and Printability of Silica-Filled Suspensions.

Although fumed silica/siloxane suspensions are commonly employed in additive manufacturing technology, the interplay between shelf life, storage conditions, and printability has yet to be explored. In this work, direct ink writing (DIW) was used to print unique three-dimensional structures that required suspensions to retain shape and form while being printed onto a substrate. Suspensions containing varying concentrations of hydrophobic and hydrophilic silica were formulated and evaluated over a time span of thirty days.

Functional Filaments: Creating and Degrading pH-Indicating PLA Filaments for 3D Printing.

With the rapid pace of advancements in additive manufacturing and techniques such as fused filament fabrication (FFF), the feedstocks used in these techniques should advance as well. While available filaments can be used to print highly customizable parts, the creation of the end part is often the only function of a given feedstock. In this study, novel FFF filaments with inherent environmental sensing functionalities were created by melt-blending poly(lactic acid) (PLA), poly(ethylene glycol) (PEG), and pH indicator powders (bromothymol blue, phenolphthalein, and thymol blue).

Balancing Functionality and Printability: High-Loading Polymer Resins for Direct Ink Writing.

Although direct ink writing (DIW) allows the rapid fabrication of unique 3D printed objects, the resins-or "inks"-available for this technique are in short supply and often offer little functionality, leading to the development of new, custom inks. However, when creating new inks, the ability of the ink to lead to a successful print, or the "printability," must be considered. Thus, this work examined the effect of filler composition/concentration, printing parameters, and lattice structure on the printability of new polysiloxane inks incorporating high concentrations (50-70 wt%) of metallic and ceramic fillers as well as emulsions.

Tuning the 3D Printability and Thermomechanical Properties of Radiation Shields.

Additive manufacturing, with its rapid advances in materials science, allows for researchers and companies to have the ability to create novel formulations and final parts that would have been difficult or near impossible to fabricate with traditional manufacturing methods. One such 3D printing technology, direct ink writing, is especially advantageous in fields requiring customizable parts with high amounts of functional fillers. Nuclear technology is a prime example of a field that necessitates new material design with regard to unique parts that also provide radiation shielding.

Long-Term Thermal Aging of Modified Sylgard 184 Formulations.

Primarily used as an encapsulant and soft adhesive, Sylgard 184 is an engineered, high-performance silicone polymer that has applications spanning microfluidics, microelectromechanical systems, mechanobiology, and protecting electronic and non-electronic devices and equipment. Despite its ubiquity, there are improvements to be considered, namely, decreasing its gel point at room temperature, understanding volatile gas products upon aging, and determining how material properties change over its lifespan. In this work, these aspects were investigated by incorporating well-defined compounds (the Ashby-Karstedt catalyst and tetrakis (dimethylsiloxy) silane) into Sylgard 184 to make modified formulations.

Tuning Thermal and Mechanical Properties of Polydimethylsiloxane with Carbon Fibers.

In order to meet the needs of constantly advancing technologies, fabricating materials with improved properties and predictable behavior has become vital. To that end, we have prepared polydimethylsiloxane (PDMS) polymer samples filled with carbon nanofibers (CFs) at 0, 0.5, 1.

Development of Antimicrobial PLA Composites for Fused Filament Fabrication.

In addition to possessing the desirable properties of being a biodegradable and biocompatible polymer fabricated from renewable resources, poly (lactic acid) (PLA) has useful mechanical and thermal attributes that has enabled it to be one of the most widely-used plastics for medicine, manufacturing, and agriculture. Yet, PLA composites have not been heavily explored for use in 3D-printing applications, and the range of feasible materials for the technology is limited, which inhibits its potential growth and industry adoption. In this study, tunable, multifunctional antimicrobial PLA composite filaments for 3D-printing have been fabricated and tested via chemical, thermal, mechanical, and antimicrobial experiments.

Nafion in Dilute Solvent Systems: Dispersion or Solution?

The morphology of Nafion (EW = 1000, Na form) in dilute solvents is investigated using small angle neutron scattering (SANS) and F NMR. SANS modeling indicates three types of particle morphology: (i) a well-defined cylindrical dispersion in glycerol and in ethylene glycol with different degrees of solvent penetration; (ii) a less-defined, highly solvated large particle (>200 nm) in water/isopropanol mixtures; and (iii) a random-coil conformation (true solution behavior) in -methylpyrrolidone. These distinct morphological characteristics of Nafion are consistent with the main and side chain mobilities measured by F NMR.

Characterization of reaction intermediate aggregates in aniline oxidative polymerization at low proton concentration.

Aggregates of reaction intermediates form during the early stages of aniline oxidative polymerization whenever the initial mole ratio of proton concentration to aniline monomer concentration is low ([H(+)](0)/[An](0) View Article and Find Full Text PDF

Multiple mixed-valence behavior in trans,trans-[(tpy)(Cl)2Os(III)(mu-1,3-N3)Os(III)(Cl)2(tpy)]+. An azido bridge from the reaction between trans-[Os(VI)(tpy)(Cl)2(N)]+ and NH3.

Reaction between the Os(VI)-nitrido complex, trans-[OsVI(tpy)(Cl)2(N)]PF6 (tpy = 2,2':6',2' '-terpyridine), and ammonia (NH3) under N2 in dry CH3CN gives the mu-1,3-azido bridged [OsII-N3-OsII]- dimer, trans,trans-NH4[(tpy)(Cl)2OsII(N3)OsII(Cl)2(tpy)]. It undergoes air oxidation to give the [OsIII-N3-OsIII]+ analogue, trans,trans-[(tpy)(Cl)2OsIII(N3)OsIII(Cl)2(tpy)]PF6 ([OsIII-N3-OsIII]PF6), which has been isolated and characterized. The structural formulation as a mu-1,3-N3 bridged complex has been established by infrared and 15N NMR measurements on the 15N-labeled forms, [OsIII-14N=15N=14N-OsIII]+, [OsIII-15N=14N=15N-OsIII]+, and [OsIII-15N=15N=15N-OsIII]+.

Formation and reactivity of the Os(IV)-azidoimido complex, PPN[Os(IV)(bpy)(Cl)(3)(N(4))].

Reactions between the Os(VI)-nitrido complexes, [OsVI(L2)(Cl)3(N)] (L2 = 2,2'-bipyridine (bpy) ([1]), 4,4'-dimethyl-2,2'-bipyridine (Me2bpy), 1,10-phenanthroline (phen), and 4,7-diphenyl-1,10-phenanthroline (Ph2phen)), and bis-(triphenylphosphoranylidene)ammonium azide (PPNN3) in dry CH3CN at 60 degrees C under N2 give the corresponding Os(IV)-azidoimido complexes, [OsIV(L2)(Cl)3(NN3)]- (L2 = bpy = [2]-, L2 = Me2bpy = [3]-, L2 = phen = [4]-, and L2 = Ph2phen = [5]-) as their PPN+ salts. The formulation of the N42- ligand has been substantiated by 15N-labeling, IR, and 15N NMR measurements. Hydroxylation of [2]- at Nalpha with O<--NMe3.