We demonstrate a rapid, selective in-tandem methanolytic-hydrolysis of poly(ethylene terephthalate) (PET) to high-purity monomers, dipotassium terephthalate and ethylene glycol, within 30 minutes at sub-boiling temperatures and ambient pressure. The augmented nucleophilicity of methoxide (CH3O–) in methanol-rich, water-lean conditions (χH2O ≤ 0.23; 0.5–1 N KOH in MeOH) drives rapid surface denudation, sloughing saponified monomers, and continually exposing fresh surface for reaction. Complete depolymerization occurs in the vitreous state (Tg ≈ 60–70◦C) despite the diminished bulk diffusivity of small molecules, confining reaction to the surface. Molecular dynamics simulations and experiments indicate that the CH3O–K+ complex activates the ester carbonyls in a methanol-rich, water-lean, low-dielectric environment through cooperative electrostatic effects. Increasing water content raises the dielectric constant and reduces the solution-phase diffusivity of the bulky hydrated CH3O–, suppressing depolymerization yields. Green chemistry metrics highlight an energy economy coefficient (ε = 5 × 10^-4 ◦C-1min^-1) and a modified environmental energy impact factor (ξ = 8400 ◦C·min) for 30 minutes at 60 ◦C, representing an 11-fold improvement in ξ over state-of-the-art methods while maintaining polyester selectivity. This approach enables chemical treatment of mixed feedstocks by disburdening consumers and manufacturers from onerous sorting, effectively diverting waste from landfills and enabling closed-loop PET recycling.

This study demonstrates the sustainable conversion of agricultural waste into high-performance fluorescent epoxy resins through direct blending of coumaric acid epoxy (CE) and ferulic acid epoxy (FE) derived from corn stover. These bio-based resins exhibit tunable photoluminescence, with emission maxima shifting from 299 nm to 841 nm as FE content increases from 0 to 33 wt%. In contrast, blends based on commercial bisphenol A diglycidyl ether (BADGE) reach emission saturation around 550 nm and exhibit phase separation at higher FE concentrations, as confirmed by light microscopy. The synthesized CE-FE blends achieve superior or comparable thermomechanical properties, including flexural moduli (3.2-3.4 GPa), glass transition temperatures, and storage moduli, relative to commercial BADGE-based resins. Impact toughness is consistent across all blends except for BADGE containing 33 wt% FE, which decreases significantly from 63 J m-1 (neat BADGE) to 12 J m-1 due to phase separation. Enhanced fluorescence intensity in CE-rich blends is attributed to their compact aromatic structures, limiting free volume and nonradiative decay. Unlike existing fluorescent epoxy systems requiring complex synthesis or additives, this straightforward blending approach provides a sustainable, high-performance alternative ideal for practical integration into biorefineries, with promising applications in optical sensors, bioimaging materials, and smart coatings.

This paper develops a machine learning methodology for the rapid and robust prediction of the glass transition temperature (Tg) for polymers for the targeted application of sustainable high-temperature polymers. The machine learning framework combines multiple techniques to develop a feature set encompassing all relative aspects of polymer chemistry, to extract and explain correlations between features and Tg, and to develop and apply a high-throughput predictive model. In this work, we identify aspects of the chemistry that most impact Tg, including a parameter related to rotational degrees of freedom and a backbone index based on a steric hindrance parameter. Building on this scientific understanding, models are developed on different types of data to ensure robustness, and experimental validation is obtained through the testing of new polymer chemistry with remarkable Tg. The ability of our model to predict Tg shows that the relevant information is contained within the topological descriptors, while the requirement of non-linear manifold transformation of the data also shows that the relationships are complex and cannot be captured through traditional regression approaches. Building on the scientific understanding obtained from the correlation analyses, coupled with the model performance, it is shown that the rigidity and interaction dynamics of the polymer structure are key to tuning for achieving targeted performance. This work has implications for future rapid optimization of chemistries.

With an estimated global cost of $2.5 trillion per year, metal corrosion represents a major challenge across all industrial sectors. Numerous inorganic and organic corrosion inhibitors have been developed, but there are growing concerns about their toxicity and impact on the environment. Here, superior organic corrosion inhibitors based on indole-3-carboxaldehyde, a compound commonly found in the digestive system, and thiosemicarbazones, a safe class of ligands, were designed and studied for mild steel in pH 1 sulfuric acid solutions. Electroanalytical techniques and gravimetric tests revealed inhibition efficiencies as high as 98.9% at 30 °C. Models using Langmuir isotherms gave adsorption equilibrium constants Kads of 2 to 9 × 104 M-1 and corresponding Gibbs free energies of adsorption (ΔGads) as high as -41.44 kJ mol-1, indicating their chemisorption. SEM images confirmed the efficacy of these corrosion inhibitors, as surface features showed limited to no changes after tests. Surface analysis by XPS and LC-MS revealed inhibitor concentrations on the order of 0.7 to 1.8 μg cm-2 for the best compounds, further underlining their performance at low concentrations. Mapping of the surface by MALDI-MS further confirmed the homogeneous coating of the steel surface, with no visible fluctuations in concentrations. As all inhibitors shared the same indole thiosemicarbazone platform, unique structure-performance relationships were drawn from theoretical calculations. Notably, DFT and AIMD explained the differences in performance, highlighting the role of side groups in the distribution of the molecular orbitals and the role of water molecules in enhancing the electronic properties of the organic corrosion inhibitors and promoting their chemisorption.

About 20-34 billion poly(ethylene terephthalate) (PET) bottles from the beverage industry leak into aquatic ecosystems annually, necessitating the development of urgent strategies to treat waterborne plastic pollution. Inspired by the scalability of water disinfection infrastructure and protocols, we present a dual depolymerization approach relying on oxidation, followed by hydrolysis. Incorporating bioderived monounsaturated C18 diacid (C18:1-DA) counits at low dosages (2-5%) in the PET backbone overcomes the diffusional limitations of depolymerizing PET in the solid state by suppressing the glass transition temperature of the copolymer by 20 degrees C. Cryomilled C18:1-PET powder suspended in an oxidant-loaded alkaline slurry underwent bulk depolymerization to oligomers at 80-100 degrees C via oxidative scissions at the internally located unsaturations. In contrast, conventional PET undergoes only minor end-chain scission under mild alkaline conditions. These oligomers are suitable for low-energy repolymerization or facile solvolysis to monomers. A permanganate-periodate oxidant couple demonstrated successful oxidation through the bulk of the polymer, which subsequently was hydrolyzed to monomers. This model system serves as a proxy for ozonolysis, followed by mild hydrolysis to reduce the energetics of alkaline hydrolysis. This integrated oxidation-hydrolysis strategy paves the way for the industrial adoption of cleaner, advanced oxidation processes, such as ozonolysis for plastic pretreatment, further enabling commercialized chemical recycling of unsaturation-containing polyesters.

This is the approved Final Technical Report for DOE Award No. DE-EE0008492. In this work, two technology areas were advanced: a) novel molecules with improved performance in the end-use application of organic corrosion inhibitors and flame retardant nylon polymers, and b) development of a systematic process for identifying biomass-derived molecules with improved performance in end-use applications.

Citric acid and malic acid are renewable organic acids with considerable market size. The reaction between the two acids in sulfuric acid at 80 °C gave an unexpected pyrone diacid. A mixture of dimethyl malate and trimethyl citrate gave a pyrone diester. These pyrones were produced in good yields on a multigram scale. The pyrone diacid represents a potentially useful monomer. Molecular electrostatic potential surfaces and dipole moments were calculated for ethyl butyrate and 4-hydroxy-6-methyl-alpha-pyrone.

Nigerapyrone A, aloenin aglycone, 4'-methyl klavuzon, and allantopyrone C were synthesized from commercially available aldehydes.

A direct synthesis of trimellitic anhydride (TMA) and hemimellitic anhydride (HMA) has been reported in which all the carbons of TMA and HMA are derived from malic acid. Acetoxy succinic anhydride represents a convenient in situ equivalent of maleic anhydride.

Here, low‐energy poly(ethylene terephthalate) (PET) chemical recycling in water: PET copolymers with diethyl 2,5‐dihydroxyterephthalate (DHTE) undergo selective hydrolysis at DHTE sites, autocatalyzed by neighboring group participation, is demonstrated. Liberated oligomeric subchains further hydrolyze until only small molecules remain. Poly(ethylene terephthalate‐ stat ‐2,5‐dihydroxyterephthalate) copolymers were synthesized via melt polycondensation and then hydrolyzed in 150–200 °C water with 0–1 wt% ZnCl 2 , or alternatively in simulated sea water. Degradation progress follows pseudo‐first order kinetics. With increasing DHTE loading, the rate constant increases monotonically while the thermal activation barrier decreases. The depolymerization products are ethylene glycol, terephthalic acid, 2,5‐dihydroxyterephthalic acid, and bis(2‐hydroxyethyl) terephthalate dimer, which could be used to regenerate virgin polymer. Composition‐optimized copolymers show a decrease of nearly 50% in the Arrhenius activation energy, suggesting a 6‐order reduction in depolymerization time under ambient conditions compared to that of PET homopolymer. This study provides new insight to the design of polymers for end‐of‐life while maintaining key properties like service temperature and mechanical properties. Moreover, this chemical recycling procedure is more environmentally friendly compared to traditional approaches since water is the only needed material, which is green, sustainable, and cheap.

We report a series of novel poly(ethylene terephthalate) (PET) copolymers with improved properties through the incorporation of bioadvantaged dimethyl 2,7-naphthalenedicarboxylate (2,7-N) as a comonomer. PET is among the most commonly used engineering thermoplastics, ubiquitous in the food packaging industry. However, its application is limited by poor thermal (low T-g) and oxygen barrier performance. A series of poly(ethylene terephthalate-stat-2,7-naphthalate) copolymers were synthesized from ethylene glycol (EG), terephthalic acid (TPA), and 2,7-N via a standard two-step melt polycondensation reaction. The 2,7-N significantly improved the thermal, mechanical, and barrier properties. The glass transition temperature (T-g > 75.4 degrees C) and thermal stability (T-d,T-5% > 405.1 degrees C) of the copolymers increase monotonically with 2,7-N content, exceeding those of PET (T-g = 69.7 degrees C T-d,T-5% = 401.4 degrees C). Moreover, the mechanical properties and the crystallization behaviors are tunable through the 2,7-N loading. Composition-optimized copolymers showed an increase of 70% and 200% in elongation at break and tensile strength, respectively. In addition, the oxygen permeability value of the copolymers containing 20% 2,7-N loading fell to P-Oe = 0.0073 barrer, a 30% improvement over that of PET. These results illustrate that the novel substitution patterns offered by biobased chemicals can translate to performance advantages in packaging materials. Finally, the fundamental structure-property relationships connecting the bioadvantaged chemicals as the comonomers to the product performance were constructed as a guide for value-added renewable polymers in the future.

Increasing demand for safe, convenient, and affordable packaging has prompted tremendous growth in singleuse plastics, with attendant increases in carbon dioxide emissions and environmental waste. This study presents a family of engineering polyesters featuring biobased naphthalate rigid segments. The proposed polyesters can serve as an eco-friendly substitute for existing packaging materials, such as poly(ethylene terephthalate) (PET). Bio-PET analogs using 2,7-naphthalate-based rigid segments of dimethyl 1,2,3,4-tetrahydronaphthalene-2,7-dicarboxylate (THN) or dimethyl 2,7-naphthalene dicarboxylate (2,7-N) were synthesized via transesterification with ethylene glycol to the bis-hydroxy ester followed by polycondensation. The proposed bionaphthalate polyesters provide unique performance advantages. In experiments, the glass transition temperature of poly(ethylene THN) was comparable to that of PET (T-g = 67.7 degrees C), and the glass transition temperature of poly(ethylene 2,7-N) was far higher (T-g = 121.8 degrees C). The thermal stability of poly(ethylene 2,7-N) far exceeded that of PET, as evidenced by its char yield of 33.4 wt % at 1000 degrees C. Moreover, the poly(ethylene 2,7-N) also produced 30% less acetaldehyde under typical processing temperatures at 250-300 degrees C. Finally, the oxygen permeability values of these naphthalate-based polymers were less than P-O2 = 0.0034 barrer, which represents a 3-fold improvement over PET (0.0108 barrer). Overall, biobased naphthalate rigid segment polyesters are promising candidates for sustainable packaging materials, particularly those requiring high gas barrier performance.

Biomass conversion, especially the development of bioprivileged molecules utilizing integration of biological and chemical processes, has shown potential to produce novel chemicals with enhanced properties. Here, organic corrosion inhibitors based on triacetic acid lactone (TAL) and 4-hydroxycoumarin (4HC) have been synthesized in good yield and tested for corrosion inhibition on mild steel in both sulfuric acid and hydrochloric acid. Sixteen novel corrosion inhibitors derived from TAL and 4HC were efficiently synthesized, and 12 of them showed high corrosion inhibition efficiency as confirmed by electrochemical impedance spectroscopy (giving values greater than 78%) and polarization analysis. While TAL-based compounds showed good corrosion inhibition performance, the 4HC-based compounds showed further improvement in corrosion inhibition performance. Scanning electron microscopy analysis of the mild steel coupon in the presence of selected inhibitors showed that corrosion was significantly diminished, with complementary X-ray photoelectron spectroscopy analysis suggesting that the inhibitor molecules strongly adsorbed on the steel surface. Quantum chemical calculations showed poor correlation between calculated parameters and the performance of these molecules. This large set of corrosion inhibitors containing a dozen promising corrosion inhibitors is useful for future rational design of corrosion inhibitors. The results demonstrate a new direction for the development of bioprivileged molecules.

The interaction of nucleic acids with their molecular targets often involves structural reorganization that may traverse a complex folding landscape. With the more recent recognition that many RNAs, both coding and noncoding, may regulate cellular activities by interacting with target molecules, it becomes increasingly important to understand how nucleic acids interact with their targets and how drugs might be developed that can influence critical folding transitions. We have extensively investigated the interaction of the Spinach2 and Broccoli aptamers with a library of small molecule ligands modified by various extensions from the imido nitrogen of DFHBI [(Z)-5-(3,5-difluoro-4-hydroxybenzylidene)-2,3-dimethyl-3,5-dihydro-4H-imidazol-4-one] that reach out from the Spinach2 ligand binding pocket. Studies of the interaction of these compounds with the aptamers revealed that polyfluorophenyl-modified ligands initiate a slow change in aptamer affinity that takes an extended time (half-life of ∼40 min) to achieve. The change in affinity appears to involve an initial disruption of the entrance to the ligand binding pocket followed by a gradual transition to a more defined structure for which the most likely driving force is an interaction of the gateway adenine with a nearby 2'OH group. These results suggest that polyfluorophenyl modifications might increase the ability of small molecule drugs to disrupt local structure and promote RNA remodeling.

A modified Sonogashira coupling of aryl iodides and propyne- was achieved using only two equivalents of propyne in THF from -78 degrees C to room temperature.

A number of 6-alkenyl pyrones were synthesized using an aldol reaction followed by a tosylate elimination sequence.

Organophosphate (OP) compounds, a family of highly hazardous chemical compounds included in nerve agents and pesticides, have been linked to more than 250,000 annual deaths connected to various chronic diseases. However, a solid-state sensing system that is able to be integrated into a clothing system is rare in the literature. This study aims to develop a nanofiber-based solid-state polymeric material as a soft sensor to detect OP compounds present in the environment. Esters of polydiacetylene were synthesized and incorporated into a cellulose acetate nanocomposite fibrous assembly developed with an electrospinning technique, which was then hydrolyzed to generate more hydroxyl groups for OP binding. Scanning electron microscopy (SEM), Fourier-transform infrared spectroscopy (FT-IR), Instron® tensile tester, contact angle analyzer, and UV–Vis spectroscopy were employed for characterizations. Upon hydrolysis, polydiacetylene esters in the cellulosic fiber matrix were found unaffected by hydrolysis treatment, which made the composites suitable for OP sensing. Furthermore, the nanofibrous (NF) composites exhibited tensile properties suitable to be used as a textile material. Finally, the NF composites exhibited colorimetric sensing of OP, which is visible to the naked eye. This research is a landmark study toward the development of OP sensing in a protective clothing system.

Pogostone, a compound with various pharmaceutical activities, is a major constituent of the essential oil preparation called Pogostemonis Herba, which is obtained from the plant Pogostemon cablin. The biosynthesis of pogostone has not been elucidated, but 4-methylvaleryl-CoA (4MVCoA) is a likely precursor. We analyzed the distribution of pogostone in P. cablin using gas chromatography-mass spectrometry (GC-MS) and found that pogostone accumulates at high levels in the main stems and leaves of young plants. A search for the acyl-activating enzyme (AAE) that catalyzes the formation of 4MVCoA from 4-methylvaleric acid was launched, using an RNAseq-based approach to identify 31 unigenes encoding putative AAEs including the PcAAE2, the transcript profile of which shows a strong positive correlation with the distribution pattern of pogostone. The protein encoded by PcAAE2 was biochemically characterized in vitro and shown to catalyze the formation of 4MVCoA from 4-methylvaleric acid. Phylogenetic analysis showed that PcAAE2 is closely related to other AAE proteins in P. cablin and other species that are localized to the peroxisomes. However, PcAAE2 lacks a peroxisome targeting sequence 1 (PTS1) and is localized in the cytosol.

Maltol triflate 3 undergoes palladium-mediated carbon-carbon bond formation with styrene, boronic acids and alkynes. Benzyl ether 2 can be acylated. The acylation products can be readily converted into furo[3,2-b]ranones. (C) 2020 Elsevier Ltd. All rights reserved.