Polyester Platform with High Refractive Indices and Closed-Loop Recyclability from CO2, 1,3-Butadiene, and Thiols.

α-Ethylidene-δ-vinyl-δ-valerolactone (EVL) is the only intermediate to synthesize copolymers of CO2 with 1,3-butadiene whose ring-opening polymerization (ROP), however, is obstructed by the tiglate group. In the contribution, EVL derivatives are synthesized through a Michael addition reaction to saturate the conjugated double bond as well as introduce various groups to synthesize polyesters with designable molecular weights (Mn = 6.9-12.8 kg·mol-1), narrow dispersities (D = 1.08-1.19), tunable glass-transition temperatures (Tg = -45-3 °C), and excellent refractive indices (nd = 1.64-1.79) via living and controlled ROP. The obtained polyesters are able to be recycled to the corresponding monomers, which can prepare comparable polymers with identical side groups, realizing the homorecycling. In addition, the retro-Michael addition reaction is established and employed, realizing heterorecycling, which can alter properties during recycling. We propose a strategy for EVL derivatives and establish the corresponding polyester platform with not only high refractive indices and tunable Tgs, but also the ability to tailor properties during recycling.

Effects of different dietary energy levels on growth performance, meat quality and nutritional composition, rumen fermentation parameters, and rumen microbiota of fattening Angus steers.

This study investigates the effects of varying energy levels in diets on Black Angus steers, focusing on growth performance, muscle composition, rumen microbial community, and their interrelationships. Twenty-seven Black Angus steers, aged approximately 22 months and weighing 520 ± 40 kilograms, were randomly divided into three groups: low-energy (LE), medium-energy (ME), and high-energy (HE). Each group consisted of nine individuals. The steers were fed diets with energy levels of 6.657 MJ/kg (LE), 7.323 MJ/kg (ME), and 7.990 MJ/kg (HE) following a 14-day pre-feeding period, with a subsequent 90-day main experimental phase. After the 90-day feeding period, both the HE and ME groups exhibited significantly higher average daily weight gain (ADG) compared to the LE group (p < 0.05). The feed-to-weight ratios were lower in the HE and ME groups compared to the LE group (p < 0.05). The HE group showed significantly higher crude fat content in the longissimus dorsi muscle compared to the LE group (p < 0.05), with total fatty acid content in the muscle surpassing that in the ME and LE groups (p < 0.05). As dietary energy levels increased, the diversity of the rumen microbial community decreased (p < 0.05), and significant differences in bacterial community structure were observed between the LE and HE groups (p < 0.05). The results suggest that higher dietary energy levels enhance growth performance and alter muscle composition in Black Angus steers, while also influencing the rumen microbial community. This study contributes to understanding optimal dietary strategies for finishing Angus cattle to improve beef quality, economic returns, and the development of standardized production procedures.

Ring-Opening Polymerization of Cyclic Acetals: Strategy for both Recyclable and Degradable Materials.

To cope with the severe plastic waste crisis, massive efforts are made to develop sustainable polymer materials whose degradation involves a disposing and decomposing to small molecule (DDM) and/or a chemical recycling to monomer (CRM) process. Polyacetals, a type of pH-responsive polymers, are degradable under acidic conditions, while highly stable under neutral and basic circumstances. As for their synthesis, the cationic ring-opening polymerization (CROP) of cyclic acetals is an elegant and promising approach, though suffering from fatal side reactions and polymerization-depolymerization equilibrium. Recent development in CRM restimulates the interest in the long-forgotten CROP method due to its inherent depolymerization characteristics. In terms of the end-of-life options, polyacetals are recyclable materials with both DDM and CRM potentials. They not only expand the scope of materials for closed-loop recycling but also help to tune the degradation properties of traditional polyesters and polyolefins. This review aims to discuss the synthesis of various polyacetals by CROP and their degradation properties from the perspectives of 1) polymerization of cyclic acetals, dioxepins, and hemiacetal esters, 2) copolymerization of cyclic acetals with heterocyclic or vinyl monomers, and 3) degradation and recycling properties of the related polymers.

How to Open the Ring of a Di-ene-Substituted-δ-Valerolactone: From Carbon Dioxide and 1,3-Butadiene to Functional Polyesters.

As a substituted-δ-valerolactone, α-ethylidene-δ-vinyl-δ-valerolactone (EVL) provides a method of utilizing carbon dioxide with 1,3-butadiene to produce functional polymers. Its di-ene-substituted lactone ring was considered inactive in polymerization in the past two decades, while successful polymerization attempts of EVL have been reported very recently. Novel synthetic strategies and functional polymers from EVL have been developed. The ring-opening reactions of EVL and the corresponding polymers as well as the ring-opening (co)polymerizations of EVL and its derivatives are highlighted in this review. The obtained functional polymers with or without facile post-polymerization modification possess unique properties, such as amphipathy, elasticity, peel resistance, etc., allowing for application potential in various fields.

Sodium Ion Pre-Intercalation of δ-MnO2 Nanosheets for High Energy Density Aqueous Zinc-Ion Batteries.

With the merits of low cost, environmental friendliness and rich resources, manganese dioxide is considered to be a promising cathode material for aqueous zinc-ion batteries (AZIBs). However, its low ion diffusion and structural instability greatly limit its practical application. Hence, we developed an ion pre-intercalation strategy based on a simple water bath method to grow in situ δ-MnO2 nanosheets on flexible carbon cloth substrate (MnO2), while pre-intercalated Na+ in the interlayer of δ-MnO2 nanosheets (Na-MnO2), which effectively enlarges the layer spacing and enhances the conductivity of Na-MnO2. The prepared Na-MnO2//Zn battery obtained a fairly high capacity of 251 mAh g-1 at a current density of 2 A g-1, a satisfactory cycle life (62.5% of its initial capacity after 500 cycles) and favorable rate capability (96 mAh g-1 at 8 A g-1). Furthermore, this study revealed that the pre-intercalation engineering of alkaline cations is an effective method to boost the properties of δ-MnO2 zinc storage and provides new insights into the construction of high energy density flexible electrodes.

A Topology-Defined Polyester Elastomer from CO2 and 1,3-Butadiene: A One-Pot-One-Step "Scrambling Polymerizations" Strategy.

It is significant and challenging to use CO2 to produce polymeric materials, especially with olefins. Here, a novel strategy named "scrambling polymerizations" is designed and performed for the copolymerization of a CO2 -and-1,3-butadiene-derived valerolactone, 3-ethylidene-6-vinyltetrahydro-2H-pyran-2-one (EVL), with ϵ-caprolactone (CL) to prepare polyesters. Anionic ring-opening polymerization of CL and conjugated addition oligomerization of EVL take place individually to form PCL and EVL oligomers, respectively. Then EVL oligomers insert into PCL by transesterification resulting in polyester P(CL-co-EVL) with a tunable topology and composition. The non-cytotoxic and degradable polyester network with elongation at break of >600 % can be used as an elastomer. We propose a method to provide polyester elastomers from CO2 and olefins for the first time, and expand the potential of transformation from sustainable feedstocks to polymeric materials.

Noble metal-free V2O5/g-C3N4 composites for selective oxidation of olefins using hydrogen peroxide as an oxidant.

Vanadium pentoxide modified graphitic carbon nitride (V2O5/g-C3N4) composites were prepared through a method of wet impregnation and calcination. The obtained samples were characterized by Fourier transform infrared spectroscopy, X-ray diffraction, thermogravimetric analysis, X-ray photoelectron spectroscopy, scanning electron microscopy, transmission electron microscopy, UV-Vis diffuse reflectance spectroscopy, photoluminescence, electron spin resonance and N2 adsorption/desorption isotherms. Oxidation of olefins was employed to evaluate the catalytic and photocatalytic activities of the prepared V2O5/g-C3N4 composites. Different weight ratios (1%, 2%, 3%, 4% and 5%) of V2O5 loaded composites were prepared and a 3% loaded composite was found to show optimal catalytic performance for the reaction. This noble metal-free catalyst showed excellent performance in the oxidation of styrene to benzaldehyde with high conversion (98.7%) and selectivity (88.4%) under visible light irradiation. A plausible mechanism was proposed for this oxidation reaction with hydrogen peroxide as an oxidant. Other styrene substrates were also selectively transformed to their corresponding aldehydes with high yields (up to 92%), using such a noble metal-free catalytic system.