Kevlar-like Aramid Polymers from Mixed PET Waste.

This work describes the synthetic approaches, spectroscopic and thermal characterization of aramid polymers prepared from waste polyethylene terephthalate (PET) via sustainable and scalable processes. Direct depolymerization of PET with aliphatic diamines under melt conditions resulted in decomposition without substantial formation of any aramid polymer. The Higashi-Ogata methodology or direct polycondensation of terephthalic acid (TPA) derived from PET waste and -phenylenediamine, resulted in oligomerization and formation of aramids with a low degree of polymerization.

Solvent-Induced Selectivity of Isoprene From Bio-Derived Prenol.

In this work we demonstrate the selective catalytic conversion of prenol, which is an allylic alcohol that can be prepared from renewable resources to isoprene. The catalyst is an inexpensive molybdenum complex (Molyvan L) designed and used as an additive for lubricants. Isoprene is generated under relatively mild reaction parameters at 130-150°C, for 2 h, under vapor pressure conditions that do not exceed 50 psi.

Carbon Fiber Reinforced Epoxy Vitrimer: Robust Mechanical Performance and Facile Hydrothermal Decomposition in Pure Water.

Conventional carbon fiber reinforced thermosetting polymers (CFRPs) are neither recyclable nor repairable due to their crosslinked network. The rapid growing CFRP market raises a serious concern of the waste management. In this work, a viable method to develop a readily recyclable CFRP based on epoxy vitrimer is introduced.

Probing the molecular design of hyper-branched aryl polyesters towards lubricant applications.

We report novel polymeric materials that may be used as viscosity index improvers (VII) for lubricant applications. Our efforts included probing the comb-burst hyper-branched aryl polyester architecture for beneficial viscosity and friction behavior when utilized as an additive in a group I oil. The monomer was designed as to undergo polymerization via polycondensation within the architectural construct (AB2), typical of hyperbranched polymers.

Anion-Tunable Properties and Electrochemical Performance of Functionalized Ferrocene Compounds.

We report a series of ionically modified ferrocene compounds for hybrid lithium-organic non-aqueous redox flow batteries, based on the ferrocene/ferrocenium redox couple as the active catholyte material. Tetraalkylammonium ionic moieties were incorporated into the ferrocene structure, in order to enhance the solubility of the otherwise relatively insoluble ferrocene. The effect of various counter anions of the tetraalkylammonium ionized species appended to the ferrocene, such as bis(trifluoromethanesulfonyl)imide, hexafluorophosphate, perchlorate, tetrafluoroborate, and dicyanamide on the solubility of the ferrocene was investigated.

Radical Compatibility with Nonaqueous Electrolytes and Its Impact on an All-Organic Redox Flow Battery.

Nonaqueous redox flow batteries hold the promise of achieving higher energy density because of the broader voltage window than aqueous systems, but their current performance is limited by low redox material concentration, cell efficiency, cycling stability, and current density. We report a new nonaqueous all-organic flow battery based on high concentrations of redox materials, which shows significant, comprehensive improvement in flow battery performance. A mechanistic electron spin resonance study reveals that the choice of supporting electrolytes greatly affects the chemical stability of the charged radical species especially the negative side radical anion, which dominates the cycling stability of these flow cells.

TEMPO-based catholyte for high-energy density nonaqueous redox flow batteries.

A TEMPO-based non-aqueous electrolyte with the TEMPO concentration as high as 2.0 m is demonstrated as a high-energy-density catholyte for redox flow battery applications. With a hybrid anode, Li|TEMPO flow cells using this electrolyte deliver an energy efficiency of ca.

Multi-electron redox reaction of an organic radical cathode induced by a mesopore carbon network with nitroxide polymers.

An organic radical based composite cathode comprised of poly(2,2,6,6-tetramethylpiperidinyloxy-4-yl methacrylate) (PTMA)-Ketjenblack was developed by a simple solvent-less electrode fabrication method. The composite cathode demonstrated a two-electron redox reaction of PTMA that is from an aminoxy anion (n-type) via a radical to an oxoammonium cation (p-type) with the corresponding redox potential at 2.8-3.

Injectable and thermogelling hydrogels of PCL-g-PEG: mechanisms, rheological and enzymatic degradation properties.

We report new injectable and thermosensitive hydrogels from polycaprolactone-graft-polyethylene glycol (PCL-g-PEG). The PCL-g-PEG polymer aqueous solution was injectable and formed a physical hydrogel at human body temperature. The rheological properties, sol-gel transition mechanisms, and in vitro degradation properties of PCL-g-PEG hydrogels were investigated.

Anthraquinone with tailored structure for a nonaqueous metal-organic redox flow battery.

A nonaqueous, hybrid metal-organic redox flow battery based on tailored anthraquinone structure is demonstrated to have an energy efficiency of ~82% and a specific discharge energy density similar to those of aqueous redox flow batteries, which is due to the significantly improved solubility of anthraquinone in supporting electrolytes.

Injectable and thermosensitive PLGA-g-PEG hydrogels containing hydroxyapatite: preparation, characterization and in vitro release behavior.

Here we report the design and characterization of injectable and thermosensitive hydrogel composites comprised of poly(lactic acid-co-glycolic acid)-g-poly(ethylene glycol)(PLGA-g-PEG) containing hydroxyapatite (HA) for potential application in bone tissue engineering. Inclusion of HA into the hydrogels would provide both enhanced mechanical properties and bioactivity to the composites. The effects of HA on the properties of the hydrogels were investigated in terms of storage modulus, sol-gel transition properties, pH and in vitro dye release behavior.

7,7,8,8-tetracyanoquinodimethane-based molecular dopants for p-type doping of OLEDs: a theoretical investigation.

The array of organic conductivity dopants used for organic light-emitting devices (OLEDs) to reduce the operating voltage and improve power efficiency is extremely limited. Here we report a comparative theoretical study between newly proposed analogues and the standard state-of-the-art conductivity dopant 2,3,5,6-tetrafluoro-7,7,8,8-tetracyanoquinodimethane (F4-TCNQ). We used density functional theory to determine the bond lengths, bond angles, and electronic properties, such as the energy of the highest occupied molecular orbital (E(HOMO)) and the lowest unoccupied molecular orbital (E(LUMO)) states.

Synthesis and application of pyridine-based ambipolar hosts: control of charge balance in organic light-emitting devices by chemical structure modification.

We studied the influence of a pyridine moiety versus a phenyl moiety when introduced in the molecular design of an ambipolar host. These pyridine-based host materials for organic light-emitting diodes (OLEDs) were synthesized in three to five steps from commercially available starting materials. The isomeric hosts have similar HOMO/LUMO energies; however, data from OLEDs fabricated using the above host materials demonstrate that small structural modification of the host results in significant changes in its carrier-transporting characteristics.