Intercalation pseudocapacitance is a faradaic electrochemical phenomenon with high power and energy densities, combining the attractive features of capacitors and batteries, respectively. Intercalation pseudocapacitive responses exhibit surface-limited kinetics by definition, without restriction from the collective of diffusion-based processes. The surface-limited threshold (SLT) corresponds to the maximum voltage sweep rate (v SLT ) exhibiting a predominantly surface-limited current response prior to the onset of diffusion-limitations. Prior studies showed increased lithium diffusivity for amorphous titania compared to anatase. Going beyond prior binary comparisons, here a continuum of amorphous titania configurations were prepared using a series of calcination temperatures to tailor both amorphous character and content. The corresponding amorphous-phase v SLT increased monotonically by 317 % with lowered calcination temperatures. Subsequent isomorphic comparisons varying a single transport parameter at a time identified solid-state lithium diffusion as the dominant diffusive constraint. Thus, performance improvements were linked to increasing the lithium diffusivity of the amorphous phase with decreased calcination temperature. This remarkably enabled 95 % capacity retention (483 � 17 C/g) with 30 s of delithiation (120 C equivalent). These results highlight how isomorphic sample series can reveal previously unidentified trends by reducing ambiguity and reiterate the potential of amorphization to realize increased performance in known materials.[a] W. van den Bergh, T.

Polymer micelles have found significant uses in areas such as drug/gene delivery, medical imaging, and as templates for nanomaterials. For many of these applications, the micelle performance depends on its size and chemical functionalization. To date, however, these parameters have often been fundamentally coupled since the equilibrium size of a micelle is a function of the chemical composition in addition to other parameters. Here, we demonstrate a novel processing pathway allowing for the chemical modification to the corona of kinetically trapped “persistent” polymer micelles, termed Persistent Micelle Corona Chemistry (PMCC). Judicious planning is crucial to this size-controlled functionalization where each step requires all reagents and polymer blocks to be compatible with (1) the desired chemistry, (2) micelle persistency, and (3) micelle dispersion. A desired functionalization can be implemented with PMCC by pairing the synthetic planning with polymer solubility databases. Specifically, poly­(cyclohexyl methacrylate-b-(diethoxyphosphoryl)­methyl methacrylate) (PCHMA-b-PDEPMMA) was prepared to combine a glassy-core block (PCHMA) for kinetic control with a block (PDEPMMA) that is able to be hydrolyzed to yield acid groups. The processing sequence determines the resulting micelle size distribution where the hydrolyzed-then-micellized sequence yields widely varying micelle dimensions due to equilibration. In contrast, the micellized-then-hydrolyzed sequence maintains kinetically trapped micelles throughout the PMCC process. Statistically significant transmission electron microscopy (TEM) measurements demonstrate that PMCC uniquely enables this functionalization with constant average micelle core dimensions. Furthermore, these kinetically trapped micelles also subsequently maintain constant micelle core size when modifying the Coulombic interactions of the micelle corona via pH changes.

Colloidal quantum dots (QDs) are attractive fluorophores for bioimaging and biomedical applications because of their favorable and tunable optoelectronic properties. In this study, the native hydrophobic ligand environment of oleate-capped sphalerite CdSe/ZnS core/shell QDs was quantitatively exchanged with a set of imidazole-bearing small-molecule ligands. Inductively coupled plasma-optical emission spectroscopy and 1H NMR were used to identify and quantify three different ligand exchange processes: Z-type dissociation of the Zn­(oleate)2, L-type association of the imidazole, and X-type anionic exchange of oleate with Cl–, all of which contributed to the overall ligand exchange.

Molecular exchange between micelles or other assemblies is measurable during size and morphology changes by combining appropriate time-resolved small-angle neutron scattering (TR-SANS) measurements with the SRR approach.

For nanoparticle (NP) polymer composites, the state of dispersion vs aggregation significantly affects optical, electronic, thermal, and mechanical properties. The switching of NP distribution states thus far was limited to polymer solutions or bulky polymer-grafted NPs. Herein, for the first time, NP distribution states within polymer films are switched by adjusting fluorophobic interactions and the enthalpy of mixing with immersion annealing. The fluorophobic effect is the tendency of fluorinated molecules to strongly phase-separate from non/less fluorinated molecules. A highly fluorophobic homopolymer, poly­(perfluorooctyl acrylate) (PFOA), was combined with gold NPs of variable fluorophobic character, prepared using mixtures of small-molecule ligands (xF-NP, where x is the mol % fluorinated ligands). Low-to-moderately fluorophobic F-NPs with PFOA were aggregated after spin coating where film swelling via immersion annealing with moderately fluorophobic trifluoro toluene (TFT) generally led to a dispersed state. In contrast, the highly fluorophobic 100F-NPs were dispersed regardless of immersion annealing. This behavior was attributed to the PFOA acting like a surfactant to enable dispersion of highly fluorophobic NPs in TFT. Since these two distinct behaviors favor nonoverlapping ranges of xF-NP compositions, the NPs with intermediate compositions exhibited limited dispersibility. This fluorophobic switchability could enable time- and chemical-selective sensing of fluorinated compounds in the future.