Full Gamut Wall Tunability from Persistent Micelle Templates via Ex Situ Hydrolysis

Abstract

The predictive self‐assembly of tunable nanostructures is of great utility for broad nanomaterial investigations and applications. The use of equilibrium‐based approaches however prevents independent feature size control. Kinetic‐controlled methods such as persistent micelle templates (PMTs) overcome this limitation and maintain constant pore size by imposing a large thermodynamic barrier to chain exchange. Thus, the wall thickness is independently adjusted via addition of material precursors to PMTs. Prior PMT demonstrations added water‐reactive material precursors directly to aqueous micelle solutions. That approach depletes the thermodynamic barrier to chain exchange and thus limits the amount of material added under PMT‐control. Here, an ex situ hydrolysis method is developed for TiO2 that mitigates this depletion of water and nearly decouples materials chemistry from micelle control. This enables the widest reported PMT range (M:T = 1.6–4.0), spanning the gamut from sparse walls to nearly isolated pores with ≈2 Å precision adjustment. This high‐resolution nanomaterial series exhibits monotonic trends where PMT confinement within increasing wall‐thickness leads to larger crystallites and an increasing extent of lithiation, reaching Li0.66TiO2. The increasing extent of lithiation with increasing anatase crystallite dimensions is attributed to the size‐dependent strain mismatch of anatase and bronze polymorph mixtures.

Tailored porous carbons enabled by persistent micelles with glassy cores

“…The control of micelle size through suppression of chain exchange is key to fabricating tailored nanostructures with independent tunability of pore and wall dimensions. All prior PMT examples 46,[49][50][51][52] relied upon a N thermodynamic barrier to inhibit chain exchange between micelles in solution as well as rapid thermal crosslinking of the material precursors directly after evaporation. However, the slowly cross-linking nature of carbon materials chemistry necessitates the development of a template with significantly enhanced degrees of persistence within a micellematerial rich environment.…”

“…Here, the effective interaction parameter is a largely enthalpic term corresponding to the interface of the solvent and the core block. In prior PMT examples, this N barrier was adjusted based upon chain size, 46 trace water content, 46,[49][50][51][52] or solvent selection. 50 In all of the prior examples, porous transition metal oxides were prepared via sol-gel chemistry where the material precursors were rapidly cross-linked by a high temperature "aging" treatment within seconds of drying via spin/dip coating.…”

Nanostructure Dependence of T‐Nb2O5 Intercalation Pseudocapacitance Probed Using Tunable Isomorphic Architectures

“…The procedure is described elsewhere in detail. [ 60 ] The molar mass of PHA was determined using a Bruker Avance III HD 300 1 H NMR by comparison to the known PEO ( M n = 20.0 kg mol −1 ) (Figure S4a and Table S1, Supporting Information). The molar mass dispersity was characterized using a Waters gel permeation chromatograph (GPC) equipped with a Waters 1525 binary pump, three styragel columns (HR1, HR3, HR5 in the effective molecular weight range of 0.1–5, 0.5–30, and 2–400 kg mol −1 , respectively), and a Waters 2414 refractive index detector.…”

“…The wall thickness was measured as the diameter on an inscribed circle between neighboring pores as described elsewhere. [ 60 ] Pore size and wall‐thickness data are presented as average values with the standard‐error‐of‐the‐mean. Cross‐sectional SEM was used to determine film thickness.…”

“…A novel nanomaterial synthesis approach termed persistent micelle templates (PMT) was recently developed to produce materials with tailored series of isomorphic architectures with nanoscale pores. [60][61][62][63][64] Here, block polymers form micelles that serve as templates for material precursors. Subsequent thermal processing converts the precursors to crystalline materials while the removal of the polymer produces a well-defined porosity.…”