Reactive nanofluids for tuning resin hardness

Polyurea resins derived from tolyldiisocyante (TDI) and a reactive solvent-free nanofluid (NF-NH2) surface-decorated with propylamines can be tuned over three to five orders of magnitude in storage modulus (10 MPa to 10 GPa) and hardness modulus (6 kPa to 4 GPa) by varying weight fractions of components. The thermal properties of this NF-NH2 are similar to several other nanofluids reported using the same bulky anionic counterion that also imparts liquidity in the absence of any solvent. This tuning suggests applications ranging from opaque protective coatings to clearcoats to sealants to adhesives

Aqueous Graphene Dispersions–Optical Properties and Stimuli-Responsive Phase Transfer

We demonstrate essentially complete exfoliation of graphene aggregates in water at concentrations up to 5% by weight (166-fold greater than previous high concentration report) using recently developed triblock copolymers and copolymeric nanolatexes based on a reactive ionic liquid acrylate surfactant. We demonstrate that the visible absorption coefficient in aqueous dispersion, 48.9 ± 1.3 cm²/mg at 500 nm, is about twice that currently accepted, and we show that this value is a greatest lower bound to extant macroscopic single sheet optical studies of graphene when one considers both fine structure constant and excitonic mechanisms of visible absorption. We also show that dilute and concentrated graphene dispersions are rheo-optical fluids that exhibit an isotropic to nematic transition upon application of a shear field, and we demonstrate stimuli-responsive phase transfer

Imidazolium‐based stabilization of aqueous multiwall carbon nanotube dispersions

Imidazolium bromide, an ionic liquid surfactant acrylate, as well as its homopolymer and various copolymers are demonstrated to be superior dispersing aids for preparing aqueous multiwall carbon nanotube (MWCNT) dispersions. We demonstrate apparent complete exfoliation in water with extinction coefficients at 500 nm of about 60 cm2 mg−1 of MWCNT dispersed, a new lower bound and the highest reported extinction to date. The efficacy or efficiency of dispersion (activated by ultrasonication) is examined in terms of a quotient of extinction and weight ratio of the active monomer and MWCNT. A rank ordering of the results obtained for seven stabilizers based on the same imidazolium bromide monomer provides insights into roles of π-overlap adsorption onto MWCNT surfaces and how hydrogel properties of some of these polymers provide stability in water at higher concentrations than previously considered feasible for surfactant-stabilized and polymer-stabilized MWCNT dispersions. Simple nanocomposite film formation is demonstrated by casting and thermal diffusivity and electrical conductivity properties are examined