Enhanced Conductivity via Homopolymer-Rich Pathways in Block Polymer-Blended Electrolytes.

The optimization of ionic conductivity and lithium-ion battery stability can be achieved by independently tuning the ion transport and mechanical robustness of block polymer (BP) electrolytes. However, the ionic conductivity of BP electrolytes is inherently limited by the covalent attachment of the ionically conductive block to the mechanically robust block, among other factors. Herein, the BP electrolyte polystyrene--poly(oligo-oxyethylene methacrylate) [PS--POEM] was blended with POEM homopolymers of varying molecular weights.

Functional group quantification of polymer nanomembranes with soft x-rays.

Polyamide nanomembranes are at the heart of water desalination, a process which plays a critical role in clean water production. Improving their efficiency requires a better understanding of the relationship between chemistry, network structure, and performance but few techniques afford compositional information in ultrathin films (<100 nm). Here, we leverage resonant soft x-ray reflectivity, a measurement that is sensitive to the specific chemical bonds in organic materials, to quantify the functional group concentration in these polyamides.

Structure Elucidation of Mixed-Linker Zeolitic Imidazolate Frameworks by Solid-State (1)H CRAMPS NMR Spectroscopy and Computational Modeling.

Mixed-linker zeolitic imidazolate frameworks (ZIFs) are nanoporous materials that exhibit continuous and controllable tunability of properties like effective pore size, hydrophobicity, and organophilicity. The structure of mixed-linker ZIFs has been studied on macroscopic scales using gravimetric and spectroscopic techniques. However, it has so far not been possible to obtain information on unit-cell-level linker distribution, an understanding of which is key to predicting and controlling their adsorption and diffusion properties.

How to measure absolute P3HT crystallinity via C CPMAS NMR.

We outline the details of acquiring quantitative C cross-polarization magic angle spinning (CPMAS) nuclear magnetic resonance on the most ubiquitous polymer for organic electronic applications, poly(3-hexylthiophene) (P3HT), despite other groups' claims that CPMAS of P3HT is strictly nonquantitative. We lay out the optimal experimental conditions for measuring crystallinity in P3HT, which is a parameter that has proven to be critical in the electrical performance of P3HT-containing organic photovoltaics but remains difficult to measure by scattering/diffraction and optical methods despite considerable efforts. Herein, we overview the spectral acquisition conditions of the two P3HT films with different crystallinities (0.

On the role of experimental imperfections in constructing (1)H spin diffusion NMR plots for domain size measurements.

We discuss the precision of 1D chemical-shift-based (1)H spin diffusion NMR experiments as well as straightforward experimental protocols for reducing errors. The (1)H spin diffusion NMR experiments described herein are useful for samples that contain components with significant spectral overlap in the (1)H NMR spectrum and also for samples of small mass (<1mg). We show that even in samples that display little spectral contrast, domain sizes can be determined to a relatively high degree of certainty if common experimental variability is accounted for and known.

Comparison of the properties of cellulose nanocrystals and cellulose nanofibrils isolated from bacteria, tunicate, and wood processed using acid, enzymatic, mechanical, and oxidative methods.

This work describes the measurement and comparison of several important properties of native cellulose nanocrystals (CNCs) and cellulose nanofibrils (CNFs), such as crystallinity, morphology, aspect ratio, and surface chemistry. Measurement of the fundamental properties of seven different CNCs/CNFs, from raw material sources (bacterial, tunicate, and wood) using typical hydrolysis conditions (acid, enzymatic, mechanical, and 2,2,6,6-tetramethylpiperidinyl-1-oxyl (TEMPO)-mediated oxidation), was accomplished using a variety of measurement methods. Atomic force microscopy (AFM), transmission electron microscopy (TEM), and 13C cross-polarization magic angle spinning (CPMAS) nuclear magnetic resonance (NMR) spectroscopy were used to conclude that CNCs, which are rodlike in appearance, have a higher crystallinity than CNFs, which are fibrillar in appearance.

Measuring Order in Regioregular Poly(3-hexylthiophene) with Solid-State C CPMAS NMR.

We report on measurements of order in semicrystalline, high molar mass poly(3-hexylthiophene) (P3HT) by solid-state C cross-polarization magic angle spinning (CPMAS) nuclear magnetic resonance (NMR) measurements. The relative degree of crystallinity was estimated for two films with different drying conditions via X-ray diffraction (XRD) and differential scanning calorimetry (DSC). Order determined by C NMR does not necessarily correlate with crystallinity, indicating that local order can occur in noncrystalline regions.

Single crystal to single crystal topochemical photoreactions: measuring the degree of disorder in the [2+2] photodimerization of trans-cinnamic acid using single-crystal 13C NMR spectroscopy.

A single crystal of α-trans-cinnamic acid was synthesized with a (13)C-label at the β-carbon position and photoreacted to yield the [2+2] cycloaddition product, α-truxillic acid. (13)C{(1)H} cross-polarization (CP) single-crystal NMR experiments were performed on the unreacted and sequentially photoreacted samples for different goniometer orientations, and the spectra were simulated using the SIMMOL and SIMPSON software packages. Atomic coordinates from single-crystal X-ray diffraction data were used as inputs in the simulations, which allowed the chemical shift tensor to be precisely measured and related to the unit cell (or molecular) reference frame of cinnamic acid.

An unexpected phase transition during the [2 + 2] photocycloaddition reaction of cinnamic acid to truxillic acid: changes in polymorphism monitored by solid-state NMR.

We have detected a phase transition during the progress of the solid-state [2 + 2] photocycloaddition reaction of alpha-trans-cinnamic acid. The reaction was monitored using (13)C CPMAS experiments as a function of irradiation time of the parent alpha-trans-cinnamic acid, which forms the product dimer, alpha-truxillic acid. UV light centered at 350 nm was used for photoirradiation, which is in the "tail" of the absorption band of cinnamic acid.

Solid-state photodimerization kinetics of alpha-trans-cinnamic acid to alpha-truxillic acid studied via solid-state NMR.

The present work focuses on the topochemical photoconversion process in which alpha-trans-cinnamic acid becomes alpha-truxillic acid. This solid-state [2 + 2] cycloaddition reaction has previously been studied with X-ray diffraction, atomic force microscopy, and vibrational spectroscopy. However structural and kinetic details about the reaction are still debated.