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The segmental dynamics of bottlebrush polymers with a stiff backbone and flexible side chains has been studied. The segmental relaxation time of side chains attached to a flexible backbone follows the same trend as linear polymers, an increase with the increasing molecular weight, but is slowed down compared to their linear counterparts. Theoretical work predicts a reversal of the molecular weight dependence of the relaxation time for stiff backbones. As a model for a stiff-g-flexible system, bottlebrushes with poly(norbornene) backbone and poly(propylene oxide) side chains, PNB-g-PPO, at a uniform grafting density have been synthesized and characterized with quasi-elastic neutron scattering. Indeed, the anticipated reversed dynamics was found. Increasing the side chain length decreases the segmental relaxation time. This indicates the importance of the characteristics of the grafting site beyond a simplified picture of an attached side chain. The mean square displacement shows a similar trend with longer side chains exhibiting a larger displacement. [ABSTRACT FROM AUTHOR]

An electrochemical–thermal tandem reaction system was designed in this work and enabled the highly efficient synthesis of propylene oxide (PO) at 1 atm without the use of H2O2. The electrochemical part produced OOH− through a 2e− oxygen reduction reaction, which migrated and distributed in the full space of a chamber filled with a mixture of solid electrolyte particles and modified TS-1 (m-TS-1) catalysts. Mediated by the relay of OOH− and protic solvent methanol, full space tandem reactions were achieved with a high PO selectivity of 95.2% and a productivity of 319.75 mmol gecat−1 h−1. A mechanistic study revealed that the m-TS-1 catalysts accepted the migrated OOH− and formed a Ti-OOH intermediate, which played a key role in relaying the tandem reactions for an efficient propylene epoxidation reaction. Techno-economic analysis and life-cycle assessment revealed favorable figures for the proposed process compared to the conventional process. [ABSTRACT FROM AUTHOR]

Titanium silicalite‐1 (TS‐1) serves as an effective catalyst for propylene epoxidation in the hydrogen peroxide propylene oxide (HPPO) process, attracting wide attention from researchers and industry. Nonetheless, the TS‐1 catalyst experienced inevitable deactivation during industrial applications, which adversely impacts its lifespan. To enhance reaction stability of catalyst, the present work conducted a systematic investigation into the deactivation reason of the TS‐1 catalyst. The fresh, deactivated, and regenerated catalysts were characterized by using various analytical techniques to compare their physicochemical properties. The surface coke species of the deactivated catalysts were extracted by the Soxhlet extraction method and subsequently analyzed using GC–MS. Additionally, the pathways for by‐product formation were simulated through Gauss software. The results indicated that the so‐called coking deposits formed during the reaction predominantly consist of propylene glycol, ethers, and oligomers. These coke species covered the partial active sites on the catalyst surface, blocked the pores of the catalyst, and accordingly led to the deactivation of the catalyst, although the crystalline structure of the catalyst hardly changed after deactivation. These results provide a theoretical basis and novel insights for the rational design and development of efficient catalysts for the HPPO process. [ABSTRACT FROM AUTHOR]

We introduce a novel concept in nucleic acid delivery based on the use of mixed polymeric micelles (MPMs) as platforms for the preparation of micelleplexes with DNA. MPMs were prepared by the co-assembly of a cationic copolymer, poly(1-(4-methylpiperazin-1-yl)-propenone)-b-poly(d,l-lactide), and nonionic poly(ethylene oxide)-b-poly(propylene oxide)-b-poly(ethylene oxide) block copolymers. We hypothesize that by introducing nonionic entities incorporated into the mixed co-assembled structures, the mode and strength of DNA binding and DNA accessibility and release could be modulated. The systems were characterized in terms of size, surface potential, buffering capacity, and binding ability to investigate the influence of composition, in particular, the poly(ethylene oxide) chain length on the properties and structure of the MPMs. Endo–lysosomal conditions were simulated to follow the changes in fundamental parameters and behavior of the micelleplexes. The results were interpreted as reflecting the specific structure and composition of the corona and localization of DNA in the corona, predetermined by the poly(ethylene oxide) chain length. A favorable effect of the introduction of the nonionic block copolymer component in the MPMs and micelleplexes thereof was the enhancement of biocompatibility. The slight reduction of the transfection efficiency of the MPM-based micelleplexes compared to that of the single-component polymer micelles was attributed to the premature release of DNA from the MPM-based micelleplexes in the endo–lysosomal compartments. [ABSTRACT FROM AUTHOR]

Titanosilicate-supported Au-cluster catalysts can be used to selectively synthesize propylene oxide from propylene using O2 and H2. However, the details of the catalytic reaction mechanism have not yet been elucidated. Thus, the reaction mechanism was investigated using density functional theory calculations. The calculation results revealed that active Ti-OOH forms on the surface Ti site, which is active as an oxidant and acts as an anchorage site for Au nanoclusters. The rate-determining step of propylene oxide synthesis on Au/titanosilicate is O insertion into propylene, with an activation energy of 1.37 eV. The propylene involved in this reaction is activated by adsorption on Au nanoclusters. Moreover, it was also found that the formation of Ti-OOH on Au/titanosilicate requires an activation energy of 0.48 eV, while it is barrierless on Au/anatase-TiO2. However, the decomposition energy of Ti-OOH on Au/titanosilicate is −0.16 eV, which is smaller than that on Au/anatase-TiO2 (−1.12 eV). The results indicate that Ti-OOH decomposes more readily on Au/titanosilicate than on Au/anatase-TiO2 but is easily regenerated because the reaction energy is significantly smaller than that on Au/anatase-TiO2. Therefore, these calculations are qualitatively in good agreement with the experimental results for Au/titanosilicate, which exhibited high catalytic activity at high temperatures. [ABSTRACT FROM AUTHOR]

Catalytic cycloaddition of CO2 with propylene oxide (PO) is a sustainable pathway for the synthesis of propylene carbonate (PC), and the design of efficient heterogeneous catalysts is a hot research topic in both C1 chemistry and functional materials. In this work, graphitic carbon nitride (g‐C3N4) materials were prepared using urea (U) and melamine (M) as precursors through one‐step thermal condensation and then applied as catalyst supports for ZnBr2. As heterogeneous catalysts, the synthesized composites (ZnBr2/g‐C3N4‐MU) exhibited higher activity in the cycloaddition reaction of CO2 to PC than ZnBr2/g‐C3N4‐M and ZnBr2/g‐C3N4‐U. The preparation temperature of ZnBr2/g‐C3N4‐MU could affect the distributions of nitrogen species and acidic strength, which thus determined the final catalytic activity. More importantly, the loading of ZnBr2 not only introduced acidic sites but also enhanced the strength of alkaline sites of g‐C3N4‐MU, enabling ZnBr2/g‐C3N4‐MU materials as acid–base bifunctional catalysts in cycloaddition of CO2 with PO. [ABSTRACT FROM AUTHOR]

Spin‐polarized density functional theory (DFT) +U calculation was performed to study propylene selective oxidation on Cu2O(111) and Cl−Cu2O(111) surfaces. The mechanism included two pathways: the allylic hydrogen stripping (AHS) pathway and the epoxidation pathway, and acrolein, propylene oxide (PO), propanal and acetone can be formed. The calculated results found that the C3H6*+OO*→OOMMP2*→PO* route can be regarded as the preferred formation route of PO on these two surfaces. On clean surface, acrolein can be regarded as the main product, then other products selectivity follows: acetone>PO>propanal. On Cl−Cu2O(111) surface, acrolein was also the main product, and the apparent activation energy of acrolein (1.97 eV) was approximated to the apparent activation energy of PO (2.04 eV), other products selectivity follows: PO>propanal>acetone, which means that the selectivity of PO can be improved by the effect of Cl. Microkinetic simulation confirm that PO selectivity can be elevated qualitatively, and found that OOMMP2*→PO2*+O* is the rate determining step on pure surface and C3H6*+OO*→OOMMP2* is the rate controlling step on the doped−Cl surface. From this work, it can be found the O−O bond in O2 can be activated effectively by the presence of Cl, enhancing the selectivity of PO. [ABSTRACT FROM AUTHOR]

Rational designation of the catalyst for efficient atom‐economic conversion of propylene oxide (PO) and carbon monoxide (CO) into β‐butyrolactone is of current significance. By employing the O,N,O‐tridentate ligands R1,R2LH2 (1–4), the aluminium compounds (R1,R2LAlCl)2 (R1,R2=H,H (5), tBu,tBu (6), Cl,Cl (7), Br,Br (8)) and the derived anion‐cation pairs [H,HLAl(THF)3]+[Co(CO)4]− (9) and [(R1,R2LAl)2Cl(THF)2]+[Co(CO)4]− (R1,R2=tBu,tBu (10), Cl,Cl (11), Br,Br (12)) as well as the aluminium‐cobalt bimetallic cluster compounds [(R1,R2LAl)2Cl(THF)][Co3(CO)10] (R1,R2=tBu,tBu (13), Cl,Cl (14), Br,Br (15)) were prepared. Compounds 9–12 efficiently catalyzed the PO carbonylation into β‐butyrolactone to achieve up 93.4–98.9 % yields while 13–15 gained 95.2–99.0 % yields all at 25 °C and 0.1 MPa CO pressure. The Lewis acidic property of the aluminium compounds 5–8 was investigated. The kinetic of the catalytic reaction using compound 10 was studied. The cooperatively catalytic reaction mechanism by the Co−Al bimetallic species is proposed. [ABSTRACT FROM AUTHOR]

The electrochemical propylene epoxidation reaction (PER) provides a promising route for ecofriendly propylene oxide (PO) production, instantly generating active halogen/oxygen species to alleviate chloride contamination inherent in traditional PER. However, the complex processes and unsatisfactory PO yield for current electrochemical PER falls short of meeting industrial application requirements. Herein, a spatial‐coupling strategy over RuO2/Ti hollow‐fiber penetration electrode (HPE) is adopted to facilitate efficient PO production, significantly improving PER performance to ampere level (achieving over 80 % PO faradaic efficiency and a maximum PO current density of 859 mA cm−2). The synergetic combination of the penetration effect of HPE and the spatial‐coupled reaction sequence, enables the realization of ampere‐level PO production with high specificity, exhibiting significant potentials for economically viable PER applications. [ABSTRACT FROM AUTHOR]

The polyethylene oxide‐polypropylene oxide (PEO‐PPO) based triblock copolymers are notable amphiphilic copolymers with a diverse range of applications. The presence of homo‐, and/or diblock impurities in copolymers with PEO‐PPO‐PEO triblock has been demonstrated. This finding suggests that the samples are blends rather than pure triblock copolymers. Furthermore, copolymers with triblock copolymer content of 0 or less than 20% by molar percentage have been identified. The hydrophilic‐lipophilic balance (HLB) is also calculated based on the exact composition of the blends. The effect of HLB values and compositional data on the initial foam height (in casein solution), the surface tension, and the contact angle are investigated. The correlation coefficients for the PPO‐PEO‐PPO copolymers versus HLB values are found to be high, while those obtained for the PEO‐PPO‐PEO copolymers versus values of HLB are significantly lower. The lower correlation coefficients for the PEO‐PPO‐PEO samples can be attributed to the presence of homo‐ and diblock (co)polymer contaminants. In addition, a linear regression model has been constructed to find a mathematical relationship between the percentage of ethylene oxide, the average number of propylene oxide units, and the properties of the copolymer. [ABSTRACT FROM AUTHOR]

The quest for sustainable synthesis of carboxylic acids has led to the exploration of innovative routes and catalysts for the oxidative cleavage of carbon−carbon double bonds, prevalent in bio‐derived molecules. This process involves multiple steps including epoxidation, hydrolysis and vicinal diol cleavage, often catalysed by unsustainable homogeneous or noble‐metal catalysts. In this study, we present the utilization of Fe‐ZSM‐5 as a versatile bifunctional catalyst capable of catalysing both hydrolysis and vicinal diol cleavage steps, utilizing propylene oxide as model compound and H2O2 as oxidizing agent. The prepared Fe‐ZSM‐5 features the zeolite intrinsic Lewis and Brønsted acidity functions, essential for the hydrolysis step, as well as high fractions of monomeric FeOx species, crucial for the subsequent vicinal diol cleavage, leading to streamlined carboxylic acids formation in a one‐pot, two‐step process. Moreover, by combining Fe‐ZSM‐5 with TS‐1, renowned for its epoxidation activity, we demonstrate the complete cascade reaction in one pot, under mild conditions, starting from ethylene. Our study expands the utility of cost‐effective zeolite‐based catalysts enriched with abundant Fe metal for the one‐pot oxidative cleavage of C=C double bonds, offering a promising pathway towards sustainable carboxylic acid synthesis. [ABSTRACT FROM AUTHOR]

A comparative study of the copolymerization of racemic propylene oxide (PO) with CO2 catalyzed by racemic (salcy)CoX (salcy = N,N′-bis(3,5-di-tert-butylsalicylidene)-1,2-diaminocyclohexane; X = perfluorobenzoate (OBzF5) or 2,4-dinitrophenoxy (DNP)) in the presence of a [PPN]Cl ([PPN] = bis(triphenylphosphine)iminium) cocatalyst is performed in bulk at 21 °C and a 2.5 MPa pressure of CO2. The increase in the nucleophilicity of an attacking anion results in the increase in the copolymerization rate. Racemic (salcy)CoX provides a high selectivity of the copolymerization, which can be higher than 99%, and the living polymerization mechanism. Poly(propylene carbonate) (PPC) with bimodal molecular weight distribution (MWD) is formed throughout copolymerization. Both modes are living and are characterized by low dispersity, while their contribution to MWD depends on the nature of the attacking anion. The racemic (salcy)CoDNP/[PPN]DNP system is found to be preferable for the production of PPC with a high yield and selectivity. [ABSTRACT FROM AUTHOR]

The polymerization and degradation behaviors of polypropylene carbonate (PPC) of different molecular weights were explored in the presence of catalyst Salen–Co(III)–Cl. The degradation of low-molecular-weight PPC (Mn = 2500 g mol−1, Đ = 1.01) was studied in detail, which was a second-order reaction related to the molar concentrations of PPC and the catalyst. Catalyzed by salen–cobalt, the degradation reaction proceeded spontaneously and could be completed at room temperature and atmospheric pressure, which provided a green and economical method for chemical degradation recycling of CO2-based polycarbonate plastics. On the basis of the degradation investigation, a method for the synthesis of cyclic propylene carbonate from propylene oxide and CO2 at room temperature and atmospheric pressure was developed. [ABSTRACT FROM AUTHOR]

Rationale: Ethylene oxide (EO) sterilization is commonly employed for the sterilization of medical devices and has a very high market share. However, EO and its metabolite ethylene chlorohydrin (ECH) are toxic to humans. In compliance with the classification and residue limits of medical devices defined by ISO 10993‐7, our study established two extraction methods for the testing of EO and ECH. Methods: The first method involves simulated‐use extraction using water as the extraction solvent. While the second, exhaustive extraction, directly extracts sample through headspace sampling analysis. Gas chromatography–tandem mass spectrometry in multiple reaction monitoring mode was utilized, requiring only 16 min. Then, the developed method was applied to assess 10 commercially available medical devices sterilized by EO. Results: In simulated‐use extraction, calibration curves were evaluated in the range of 1–100 and 5–500 μg for EO and ECH, respectively (r > 0.999). Inter‐day recoveries ranged from 85.0% to 95.2% and from 94.8% to 102.4%. In exhaustive extraction, calibration curves spanned 0.5–50 and 2–200 μg for EO and ECH, respectively (r > 0.999). Inter‐day recoveries ranged from 101.6% to 102.1% for EO and from 98.1% to 102.2% for ECH. After analysis of the 10 commercially available medical devices, two cotton swabs were found to have ECH of 35.1 and 28.4 μg per device, and four medical devices were found to have EO with concentration below the limit of quantification. Meanwhile, we found that the EO internal standard (propylene oxide) recommended by ISO 10993‐7 had interference problems with other similar substances and was not suitable as an internal standard for EO. Conclusions: This study offers a sensitive and straightforward analytical approach to EO and ECH residues in a variety of medical devices. In addition, the results show that the EO or ECH content of these types of medical devices in our study falls below the regulatory limits, therefore instilling confidence among consumers regarding their safe use. [ABSTRACT FROM AUTHOR]

Double metal cyanide (DMC) complexes represent a unique family of materials with an open framework structure. The main current application of these complexes in chemical industry is their use as catalysts (DMCCs) of the ring-opening polymerization of propylene oxide (PO), yielding branched polyols, highly demanded in production of polyurethanes and surfactants. The actual problem of chemical fixing carbon dioxide from the atmosphere gave new impetus to the development of DMCCs, which turned out to be effective in oxirane/CO2 copolymerization. In recent years, new types and formulations of DMCCs were created, so that greater understanding of the reaction mechanisms was achieved and new fields of catalytic applications were found. In the present review, we summarized background and actual information about the synthesis, structure, and mechanisms of the action of DMCCs, as well as their application in the development of new materials and fine chemicals. [ABSTRACT FROM AUTHOR]

This study describes the physicochemical characterisation of interpenetrating hydrogel networks (IHNs) composed of either poly(hydroxyethylmethacrylate, p(HEMA)) or poly(methacrylic acid, p(MAA)), and Pluronic block copolymers (grades F127, P123 and L121). IHNs were prepared by mixing the acrylate monomer with Pluronic block copolymers followed by free radical polymerisation. p(HEMA)–Pluronic blends were immiscible, evident from a lack of interaction between the two components (Raman spectroscopy) and the presence of the glass transitions (differential scanning calorimetry, DSC) of the two components. Conversely, IHNs of p(MAA) and each Pluronic were miscible, displaying a single glass transition and secondary bonding between the carbonyl group of p(MAA) and the ether groups in the Pluronic block copolymers (Raman and ATR-FTIR spectroscopy). The effect of storage of the IHNs in Tris buffer on the physical state of each Pluronic and on the loss of Pluronic from the IHNs were studied using DSC and gravimetric analysis, respectively. Pluronic loss from the IHNs was dependent on the grade of Pluronic, time of immersion in Tris buffer, and the nature of the IHN (p(HEMA) or p(MAA)). At equilibrium, the loss was greater from p(HEMA) than from p(MAA) IHNs, whereas increasing ratio of poly(propylene oxide) to poly(ethylene oxide) decreased Pluronic loss. The retention of each Pluronic grade was shown to be primarily due to its micellization; however, hydrogen bonding between Pluronic and p(MAA) (but not p(HEMA)) IHNs contributed to their retention. [ABSTRACT FROM AUTHOR]

A series of hollow VOx/SiO2 nanofiber catalysts (nV/S-f) with vanadium content ranging from 0.25 wt% to 4.0 wt% were prepared by electrospinning-calcination, and characterized by ICP-MS, XRD, N2 adsorption–desorption, SEM, XPS, UV–Vis-DRS and H2-TPR. Subsequently, the performance of these catalysts in the oxidative dehydrogenation of propane (ODHP) was evaluated. It was found that vanadium species with high dispersivity were obtained when the V content was less than 1.5 wt%. By comparison, 1.0V/S-f catalyst had the best catalytic performance, especially in terms of the propylene selectivity at high-temperature: ~ 77% at 550 °C and ~ 74% at 575 °C. In contrast to the conventional impregnation technique, the catalyst with one-dimensional nanostructure has more catalytic advantages. [ABSTRACT FROM AUTHOR]

A PPC‐dodecyl glucoside (PPC‐APG) polymer was synthesized by the terpolymerization of carbon dioxide (CO2), propylene oxide (PO), and the bio‐based monomer APG for the first time. The thermal stability and mechanical properties of PPC‐APG were significantly improved compared with those of conventional polypropylene carbonate (PPC), and its glass transition temperature (Tg) was increased by 14°C compared with that of PPC. The 5% heat loss temperature (Td,−5%) and total heat loss temperature (Td,max) of PPC‐APG were increased by 89.1 and 92.1°C, respectively, compared with those of PPC. The tensile strength of PPC‐APG was increased to 25.6 MPa, its elongation at break was decreased to 125.1%, and its thermal elongation and permanent deformation were reduced to 97.2% and 62.9%, respectively, which improved the processability of the material. In addition, the introduction of bio‐based monomers also rendered PPC‐APG functional, and its surface tension reached a maximum of 61.3 mN/m at a concentration of 0.05 g/mL, with a good degradability. The higher surface tension and enhanced degradability of PPC‐APG indicate its potential for application as a plastic printing substrate. [ABSTRACT FROM AUTHOR]

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The design and synthesis of efficient carbon‐based materials incorporating multifunctional sites is prospective technology for converting carbon dioxide (CO2) into high‐value chemicals. Here, nitrogen‐doped carbon catalysts (ZnAl‐NC) with bimetal zinc–aluminum sites were synthesized using nitrogen‐rich polyaniline (PANI) and ZnAl‐LDH through hydrothermal and in situ pyrolysis methods. ZnAl‐NC‐400, in the presence of tetrabutylammonium bromide (TBAB), exhibited excellent catalytic activity without solvent, achieving high yields (97.2% or 98.5%) in the cycloaddition of CO2 with propylene oxide (PO) under traditional or mild conditions. NH3‐TPD and CO2‐TPD results indicated that the enhanced catalytic activity resulted from the acid–base synergistic effect, involving Lewis acid sites from Zn and Al species and abundant Lewis base sites from the PANI matrix. The impact of calcination temperature on catalyst morphology, structure, and performance was investigated, along with catalyst recycling and adaptability to various epoxides. This work presents an efficient catalyst for CO2 conversion and suggests new approaches for designing catalytic sites in carbon‐based catalysts for CO2 capture and utilization. [ABSTRACT FROM AUTHOR]

A hierarchical structure alumina with high surface area was synthesized using a sol-gel method assisted by propylene oxide (PO), which was subsequently converted into alumina exhibiting different transitional phases (γ, δ, θ) through varying calcination temperatures. These aluminas were employed as substrates for the active copper phase in the RWGS catalyst, facilitating a systematic exploration of how the alumina phase influences catalyst performance. The characterized catalysts underwent assessments using techniques such as N 2 adsorption-desorption, XRD, H 2 -TPR, CO 2 -TPD, FESEM, and HRTEM. An examination of the impact of copper loading (ranging from 5.0 to 20.0 wt%) in the Cu/γ-Al 2 O 3 catalyst on RWGS performance revealed that the catalyst containing 15.0 wt% Cu exhibited the highest CO 2 conversion rate, achieving 8% at 300 °C under a 1CO 2 :1H 2 ratio at atmospheric pressure. This specific catalyst demonstrated 100% selectivity for CO. Evaluating the extended stability of Cu catalysts supported by γ-, δ-, and θ-Al 2 O 3 phases, all loaded with the same amount of Cu (15.0 wt%), was carried out at 450 °C. The δ- and θ-Al 2 O 3 -supported catalysts were able to maintain approximately 100% of their initial catalytic activities after 72 h, whereas the activity of the catalyst supported by γ-Al 2 O 3 decreased. The examination of the crystalline phases of the catalyst support and stability testing demonstrated the significant impact of porosity on mass transfer and the diffusion processes of reactants and production on the structure of the catalyst. This study revealed how adjusting the macropore size and porosity within various crystalline phases can optimize the filling degree and achieve an ideal balance between reaction and mass transfer rates. [Display omitted] • Catalyst support with the highest surface area was prepared via a sol-gel method. • Effect of hierarchical alumina as catalyst support was investigated in RWGS reaction. • 15 wt% Cu/γ-Al 2 O 3 catalyst exhibited the highest CO 2 conversion of 8% at 300 °C. • CO selectivity was 100% over 15 wt% Cu/γ-, δ-, and θ-Al 2 O 3 catalysts. [ABSTRACT FROM AUTHOR]

Selective polymerization with heterogeneous catalysts from mixed monomers remains a challenge in polymer synthesis. Herein, we describe that nano-sized zinc glutarate (ZnGA) can serve as a catalyst for the selective copolymerization of phthalic anhydride (PA), propylene oxide (PO) and lactide (LA). It was found that the ring-opening copolymerization (ROCOP) of PA with PO occurs firstly in the multicomponent polymerization. After the complete consumption of PA, the ring-opening polymerization (ROP) of LA turns into the formation of block polyester. In the process, the formation of zinc–alkoxide bonds on the surface of ZnGA accounts for the selective copolymerization from ROCOP to ROP. These results facilitate the understanding of the heterogeneous catalytic process and offer a new platform for selective polymerization from monomer mixtures. [ABSTRACT FROM AUTHOR]

The chemical industry must reduce greenhouse gas emissions to align with the Paris Agreement. In this study, we assess the economic feasibility of electrochemical oxidations (i.e., using water and electricity to create reactive oxygen species) as an alternative to current energy- and emissions-intensive industrial methods for producing ethylene oxide (EO) and glycol (EG) and propylene oxide (PO) and glycol (PG). Technoeconomic analyses reveal ethylene electrooxidations in a gas diffusion electrode assembly reach economic viability at single-pass conversions above 70% for EO and 40% for EG with overall Faradaic efficiencies (FE) above 20% and high carbon selectivities toward the desired products. Propylene electrooxidation achieves economic feasibility at a minimum single-pass conversion of 10% and overall FE greater than 10% for both PO and PG, while allowing variance in carbon selectivity. These electrochemical methods require current densities of at least 0.1 A cm-2 and lifetimes greater than 2 years for industrial scalability. We demonstrate that electrochemical oxidations can reduce emissions and operational hazards in the production of key chemical intermediates through benchmarking targets for the experimental advancement of alkene electrooxidations. [ABSTRACT FROM AUTHOR]

The anti‐emulsification property of lubricating oil is an important index to measure the quality of oil. In this paper, the behaviour of surfactants such as lubricating oil additives at the oil–water interface and the influence of the position of ethylene oxide (EO) and propylene oxide (PO) in the block polyether demulsifier on the demulsification effect were investigated by molecular simulation and experimental verification. The properties of seven lubricating oil additives with different functions and two pairs of isomers were investigated by molecular simulation, and their demulsification effects were verified by experiments. Some simulation results such as interface thickness and density distribution can accurately predict the experimental demulsification effect. Moreover, it was found that the position isomerism of surfactants affected the demulsification performance by changing the lipophilic balance and interface properties. The demulsification performance of sequenced copolymers is generally better than that of anti‐sequenced copolymers. The accurate prediction of molecular dynamics simulation makes the selection of lubricating oil demulsifier more extensive and has practical application value. [ABSTRACT FROM AUTHOR]

In this paper, macroporous high‐entropy spinel oxide (HESO) (Fe0.2Ni0.2Co0.2Mn0.2Zn0.2)3O4 monoliths were successfully fabricated via a sol–gel method followed by calcination. Appropriate polyacrylic acid and propylene oxide contents allow the formation of three‐dimensional co‐continuous xerogel monoliths, and the water/glycerol ratio controls the macropore size of monoliths. Subsequent calcination achieves the precipitation of HESO (Fe0.2Ni0.2Co0.2Mn0.2Zn0.2)3O4 with a singular phase and exceptional structural stability. The macroporous HESO (Fe0.2Ni0.2Co0.2Mn0.2Zn0.2)3O4 demonstrates remarkable performance in the oxygen evolution reaction (OER) with an overpotential of 333 mV at 100 mA cm−2 and a Tafel slope of 43.2 mV dec–1, surpassing that of RuO2 (391 mV) under identical conditions. Furthermore, the catalytic stability of the HESO catalyst remains superior even after 24 h of testing. This process offers a promising avenue for the development of macroporous high‐entropy oxide OER catalysts for overall water splitting. [ABSTRACT FROM AUTHOR]

The development of green route for preparing propylene oxide (PO) with molecular oxygen is of significance both in academic and industrial. In this work, propylene epoxidation coupled with furfural oxidation catalyzed by platinum meso-tetraphenylporphyrin (Pt (II)TPP) has been developed. Propylene conversion and PO selectivity reached up to 56% and 83%, respectively. Meanwhile, furfural was almost completely converted to furoic acid. Based on operando characterizations and electron paramagnetic resonance (EPR) tests, a mechanism involved high-valent Pt species was proposed. This work is expected to provide a potential application prospects for producing PO and furoic acid simultaneously in chemical industry. [ABSTRACT FROM AUTHOR]

Sago starch is a locally abundant starch indigenous of Indonesia. Despite its abundance, it is underutilized and restricted to food and packaging applications due to its limited functional characteristics. The value of native sago starch can be increased through modifications that improve its functionality, such as dual chemical modification. This sophisticated approach is more effective than single modification and makes the starch suitable for wider applications. Our study aimed to determine if dual chemical modification involving hydroxypropylation and succinylation would optimize the functional properties of sago starch. The sago starch was first modified by hydroxypropylation with 7 % (w/w) propylene oxide under alkaline conditions for 3 hours. This process resulted in hydroxypropylated starch with a substitution degree of 0.107. We then subjected the starch to succinylation using succinic anhydride at 1 % to 5 % of the starch weight in an alkaline solution for 2 hours. We achieved optimal functional characteristics of the dual-modified sago starch in the sample modified with 3 % (w/w) of succinic anhydride. The succinyl degree of substitution, water holding capacity, oil holding capacity, swelling power, and solubility of the dual-modified starch were 0.093, 4.16 g g􀀀1, 7.20 g g􀀀1, 34.25 g g􀀀1, and 16:55 %, respectively. We conducted pasting properties analyses, infrared spectroscopy, and morphological structure analysis to determine the changes in the characteristics of the sago starch after hydroxypropylation and succinylation. The dual chemical modification successfully enhanced the functional characteristics of sago starch, particularly, its amphiphilic ability and swelling power. These results warrant further research and development in commercial applications.

Porous polymer beads with grafted poly(tertiary amine) were prepared by grafting triethylenetetramine to porous crosslinked poly(methyl acrylate) beads via ester amidation reaction, followed by Eschweiler–Clarke methylation reaction using formaldehyde and formic acid to converting the primary and secondary amine groups to tertiary amines in the beads. The tertiary amine groups in the beads were protonated with hydrochloric acid, hydrobromic acid or hydriodic acid, and the protonated tertiary amine group-containing beads showed high catalytic activity and high selectivity for the formation of propylene carbonate through cycloaddition of propylene oxide with CO2, while free tertiary amine group-containing beads exhibited almost no catalytic activity. The recyclability of the catalyst was studied, and slight loss of the activity was observed after five runs. [ABSTRACT FROM AUTHOR]

A series of functional cross-linked polystyrenes was synthesized by the free radical copolymerization of divinylbenzene with functional styrenes and utilized as heterogeneous catalysts for the coupling of epoxides with CO2. Investigations showed that the cross-linked copolymer functionalized by quaternary ammonium chloride (CP1) exhibited high catalytic activity in the coupling reaction and thermostability at elevated temperatures. Thus, CP1 was easily recycled from the reaction mixture by filtration and reused without obvious loss of activity. Moreover, the activity of CP1 can be greatly enhanced by adding conventional Lewis acids such as anhydrous FeCl3 or AlCl3. Thus, copolymer 1/FeCl3 composites (1/1 molar ratio) transformed propylene oxide and CO2 to propylene carbonate in 92% yield in 10 h at 110 °C with the composite catalyst loading of 0.25 mol% with respect to propylene oxide and can be reused after simple filtration without significant decline of activity. [ABSTRACT FROM AUTHOR]

Plastics, fibers and rubber are three mainstream synthetic materials that are essential to our daily lives and contribute significantly to the quality of our lives. The production of the monomers of these synthetic polymers usually involves oxidation or ammoximation reactions of olefins and analogues. However, the utilization of C, O and N atoms in current industrial processes is <80%, which represents the most environmentally polluting processes for the production of basic chemicals. Through innovation and integration of catalytic materials, new reaction pathways, and reaction engineering, the Research Institute of Petroleum Processing, Sinopec Co. Ltd. (RIPP) and its collaborators have developed unique H2O2-centered oxidation/ammoximation technologies for olefins and analogues, which has resulted in a ¥500 billion emerging industry and driven trillions of ¥s' worth of downstream industries. The chemical and engineering bases of the production technologies mainly involve the integration of slurry-bed reactors and microsphere catalysts to enhance H2O2 production, H2O2 propylene/chloropropylene epoxidation for the production of propylene oxide/epichlorohydrin, and integration of H2O2 cyclohexanone ammoximation and membrane separation to innovate the caprolactam production process. This review briefly summarizes the whole process from the acquisition of scientific knowledge to the formation of an industrial production technology by RIPP. Moreover, the scientific frontiers of H2O2 production and related oxidation/ammoximation processes of olefins and analogues are reviewed, and new technological growth points are envisaged, with the aim of maintaining China's standing as a leader in the development of the science and technologies of H2O2 production and utilization. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Food Safety & Quality is the property of Journal of Food Safety & Quality Editorial Department and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Polyolefin‐b‐poly(ethylene oxide) (PEO) represents the most widely investigated amphiphilic block copolymers. So far, one‐pot continuous synthesis of such hybrid block copolymers has only been fulfilled by anionic polymerization through sequential addition of vinyl monomers and ethylene oxide (EO). It still remains challenging to achieve altogether high block efficiency, high polymerization efficiency, and high molar mass for PEO. Here, we report a one‐pot hybrid block copolymerization approach to polyisoprene/polystyrene(PI/PS)‐b‐PEO, in which PI/PS are formed by sBuLi‐initiated anionic vinyl‐addition polymerization, then in situ employed as macroinitiators for the anionic ring‐opening polymerization (ROP) of EO aided by an organic Lewis pair. The cooperative (dual‐ion‐complexing) catalytic effect of organobase and triethylborane is proven, for the first time, effective for lithium alkoxide initiator system, allowing to achieve at room temperature high ROP activity (complete EO conversion and PEO of 3–64 kg/mol reached in 1–6 h), narrow molar mass distribution, controlled block lengths and composition. Density functional theory calculation shows that phosphazene bases are particularly effective, compared with N‐heterocyclic bases, for complexing with Li+ and enhancing the nucleophilicity of oxyanion. The rate of ROP is also affected by Li+‐induced aggregation of the chain‐end ion pairs, which though can be offset by adequate catalyst loadings. The versatility of this approach is further demonstrated in the one‐pot synthesis of tri‐/tetrablock ter‐/quaterpolymers constituted by PI, PS, PEO, and poly(propylene oxide). Of great interest, PS‐b‐PI‐b‐PEO triblock terpolymer with a specific composition is found to form internally microphase‐separated micellar aggregates when dispersed in water. [ABSTRACT FROM AUTHOR]

Borane catalysis has emerged as a powerful technology in epoxide polymerization. Still, the structure‐activity correlations for these catalysts are not fully understood to date, especially regarding compounds with nonionic backbones. Thus, in this work, 13 different borane catalysts of this respective type are described and investigated for their epoxide oligomerization and polymerization performance, using propylene oxide (PO), 1‐butylene oxide (BO) and allyl glycidyl ether (AGE) as monomers. Structurally, special emphasis is put on catalysts with different linker lengths and linker flexibilities as well as the introduction of more than two borane functionalities. Importantly, this screening is conducted both under typical polymerization conditions as well as under the chain transfer agent (CTA)‐rich conditions relevant for large‐scale production. It is found that suitable preorganization of the borane groups, such as present in biphenyl derivatives, offers a simple route to high‐performing catalysts and quantitative monomer conversion of the investigated epoxides. Furthermore, it is demonstrated that a diborane‐catalyzed oligomerization can be kept active over weeks, whereby repeated addition of monomer batches (14 steps) constantly results in full conversion and well‐defined oligoethers, underlining the practical potential of this method. The absence of co‐initiating counter ions is suggested as an inherent advantage of nonionic catalysts. [ABSTRACT FROM AUTHOR]

We report a new class of degradable fluorinated polymers through the copolymerization of tetrafluorophthalic anhydride and propylene oxide or trifluoropropylene oxide which show up to 20 times quicker degradation than the non-fluorinated equivalents and allow for fluoride recovery. [ABSTRACT FROM AUTHOR]

Vapor‐phase propylene (C3H6) epoxidation kinetics with hydrogen peroxide (H2O2) strongly reflects the physical properties of Ti‐incorporated zeolite catalysts and the presence of spectating molecules ("solvent") near active sites even without a bulk liquid phase. Steady‐state turnover rates of C3H6 epoxidation and product selectivities vary by orders of magnitudes, depending on the zeolite silanol ((SiOH)x) density, pore topology (MFI, *BEA, FAU), and the quantity of condensed acetonitrile (CH3CN) molecules nearby active sites, under identical reaction mechanisms sharing activated H2O2 intermediates on Ti surfaces. Individual kinetic analyses for propylene oxide (PO) ring‐opening, homogeneous diol oxidative cleavage, and homogeneous aldehyde oxidation reveal that secondary reaction kinetics following C3H6 epoxidation responds more sensitively to the changes in zeolite physical properties and pore condensation with CH3CN. Thus, higher PO selectivities achieved in hydrophilic Ti‐MFI at steady‐state reflect the preferential stabilization of transition states for C3H6 epoxidation (a primary reaction) relative to PO ring‐opening and oxidative cleavage (secondary reactions) that solvation effects that reflect interactions among condensed CH3CN within pores and the extended pore structure. [ABSTRACT FROM AUTHOR]

Vapor‐phase propylene (C3H6) epoxidation kinetics with hydrogen peroxide (H2O2) strongly reflects the physical properties of Ti‐incorporated zeolite catalysts and the presence of spectating molecules ("solvent") near active sites even without a bulk liquid phase. Steady‐state turnover rates of C3H6 epoxidation and product selectivities vary by orders of magnitudes, depending on the zeolite silanol ((SiOH)x) density, pore topology (MFI, *BEA, FAU), and the quantity of condensed acetonitrile (CH3CN) molecules nearby active sites, under identical reaction mechanisms sharing activated H2O2 intermediates on Ti surfaces. Individual kinetic analyses for propylene oxide (PO) ring‐opening, homogeneous diol oxidative cleavage, and homogeneous aldehyde oxidation reveal that secondary reaction kinetics following C3H6 epoxidation responds more sensitively to the changes in zeolite physical properties and pore condensation with CH3CN. Thus, higher PO selectivities achieved in hydrophilic Ti‐MFI at steady‐state reflect the preferential stabilization of transition states for C3H6 epoxidation (a primary reaction) relative to PO ring‐opening and oxidative cleavage (secondary reactions) that solvation effects that reflect interactions among condensed CH3CN within pores and the extended pore structure. [ABSTRACT FROM AUTHOR]

The nanocomposites of polythiourethane (PTU) with Fe3O4 were fabricated via an isocyanate-free approach. The nanocomposites simultaneously had the reprocessing, shape memory and photothermal properties. First, a linear PTU carrying a plethora of thiol groups was synthesized via the ring opening polyaddition between a bicyclic trithiocarbonate and a poly (propylene oxide) diamine. In the meantime, the surfaces of Fe3O4 nanoparticles were functionalized with thiol groups. Second, the co-crosslinking between the linear PTU and the thiol-functionalized Fe3O4 was performed via the coupling of thiol radicals with a radical initiator. Notably, the nanocomposites of PTU with Fe3O4 were successfully obtained with the fine dispersion of Fe3O4 nanoparticle in PTU matrix. Compared to control PTU, the nanocomposites displayed the improved thermomechanical properties. More importantly, the nanocomposites had reprocessing properties. The dynamic exchange of disulfide bonds is responsible for the reprocessing behavior. Owing to the crosslinking with disulfide bonds, PTU had shape memory properties. Notably, the incorporation of Fe3O4 nanoparticles was capable of improving the shape memory properties. In addition, the nanocomposites displayed the photothermal properties with the incorporation of Fe3O4 nanoparticles. The photothermal conversion behavior can be utilized to trigger the shape recovery of the nanocomposites under near-infrared light irradiation and in a non-contact fashion. [ABSTRACT FROM AUTHOR]

Vapor‐phase propylene (C3H6) epoxidation kinetics with hydrogen peroxide (H2O2) strongly reflects the physical properties of Ti‐incorporated zeolite catalysts and the presence of spectating molecules ("solvent") near active sites even without a bulk liquid phase. Steady‐state turnover rates of C3H6 epoxidation and product selectivities vary by orders of magnitudes, depending on the zeolite silanol ((SiOH)x) density, pore topology (MFI, *BEA, FAU), and the quantity of condensed acetonitrile (CH3CN) molecules nearby active sites, under identical reaction mechanisms sharing activated H2O2 intermediates on Ti surfaces. Individual kinetic analyses for propylene oxide (PO) ring‐opening, homogeneous diol oxidative cleavage, and homogeneous aldehyde oxidation reveal that secondary reaction kinetics following C3H6 epoxidation responds more sensitively to the changes in zeolite physical properties and pore condensation with CH3CN. Thus, higher PO selectivities achieved in hydrophilic Ti‐MFI at steady‐state reflect the preferential stabilization of transition states for C3H6 epoxidation (a primary reaction) relative to PO ring‐opening and oxidative cleavage (secondary reactions) that solvation effects that reflect interactions among condensed CH3CN within pores and the extended pore structure. [ABSTRACT FROM AUTHOR]

Vapor‐phase propylene (C3H6) epoxidation kinetics with hydrogen peroxide (H2O2) strongly reflects the physical properties of Ti‐incorporated zeolite catalysts and the presence of spectating molecules ("solvent") near active sites even without a bulk liquid phase. Steady‐state turnover rates of C3H6 epoxidation and product selectivities vary by orders of magnitudes, depending on the zeolite silanol ((SiOH)x) density, pore topology (MFI, *BEA, FAU), and the quantity of condensed acetonitrile (CH3CN) molecules nearby active sites, under identical reaction mechanisms sharing activated H2O2 intermediates on Ti surfaces. Individual kinetic analyses for propylene oxide (PO) ring‐opening, homogeneous diol oxidative cleavage, and homogeneous aldehyde oxidation reveal that secondary reaction kinetics following C3H6 epoxidation responds more sensitively to the changes in zeolite physical properties and pore condensation with CH3CN. Thus, higher PO selectivities achieved in hydrophilic Ti‐MFI at steady‐state reflect the preferential stabilization of transition states for C3H6 epoxidation (a primary reaction) relative to PO ring‐opening and oxidative cleavage (secondary reactions) that solvation effects that reflect interactions among condensed CH3CN within pores and the extended pore structure. [ABSTRACT FROM AUTHOR]

In this study, the impact of ethylene oxide, propylene oxide, 1,2-butene oxide, and 1,2-pentene oxide on the polymerization of propylene at an industrial level was investigated, focusing on their influence on the catalytic efficiency and the properties of polypropylene (PP) without additives. The results show that concentrations between 0 and 1.24 ppm of these epoxides negatively affect the reaction's productivity, the PP's mechanical properties, the polymer's fluidity index, and the PP's thermal properties. Fourier transform infrared spectroscopy (FTIR) revealed bands for the Ti-O bond and the Cl-Ti-O-CH2 bonds at 430 to 475 cm−1 and 957 to 1037 cm−1, respectively, indicating the interaction between the epoxides and the Ziegler–Natta catalyst. The thermal degradation of PP in the presence of these epoxides showed a similar trend, varying in magnitude depending on the concentration of the inhibitor. Sample M7, with 0.021 ppm propylene oxide, exhibited significant mass loss at both 540 °C and 600 °C, suggesting that even small concentrations of this epoxide can markedly increase the thermal degradation of PP. This pattern is repeated in samples with 1,2-butene oxide and 1,2-pentene oxide. These results highlight the need to strictly control the presence of impurities in PP production to optimize both the final product's quality and the polymerization process's efficiency. [ABSTRACT FROM AUTHOR]

Ga2O3/MCM-41-x (x = 0.4, 0.5, 0.6) heterogeneous catalysts, each with varying levels of Br doping, were synthesized using mesoporous molecular sieves (MCM-41) as a carrier and employed in the synthesis of propylene carbonate (PC) from propylene oxide (PO) and carbon dioxide (CO2). The reaction was conducted under solvent-free and additive-free conditions. Various techniques were utilized to characterize the catalysts' chemical composition, morphology, and structure. The effects of varied reaction conditions on PO conversion and PC selectivity using Ga2O3/MCM-41-0.5 catalysts were investigated. Under the reaction conditions of 120 °C, 3.5 MPa, 10 h and catalyst dosage of 2.6 wt%, the PO conversion and PC selectivity reached 99.7% and 99.1%, respectively. The catalytic impact correlates strongly with the doping amounts of Ga2O3 and Br, primarily due to the interaction of Ga2O3 with the surface of MCM-41, leading to the generation of more basic sites and, consequently, a greater abundance of alkali centers. As a nucleophilic reagent, Br functions synergistically with Ga2O3/MCM-41, augmenting the ring-opening rate of PO and improving the activation ability of CO2. The stability of the catalyst underwent evaluation, revealing a slight decrease in activity after repeated use. The reaction mechanism underlying PC synthesis catalyzed by Ga2O3/MCM-41-0.5 was speculated. [ABSTRACT FROM AUTHOR]

The ternary copolymerization of a series of cyclic anhydrides with epoxides and carbon dioxide using dinuclear [OSSO]‐type chromium (III),1, and ‐iron(III), 2, complexes (0.1 mol %) in combination with (bis(triphenylphosphine)iminium chloride) (PPNCl, 0.5–1.0 mol with respect to catalyst) as co‐catalyst is reported in this study. The results have yielded copolymers with polyester and polycarbonate segments with high molecular weights and narrow dispersity. The catalytic systems 1–2/PPNCl were tested in the copolymerization of different epoxides, such as propylene oxide (PO), cyclohexene oxide (CHO), and vinylcyclohexene oxide (VCHO), with a variety of cyclic anhydrides, such as phthalic (PA), diglycolic (DGA) and succinic (SA), with CO2 pressure of 20 bar, temperature range of 45–80 °C in 24 h. Anhydride reaction, affording the polyester segments, exceeded the conversion of 99 % in all the explored cases. On the other hand, in the case of epoxide copolymerization with CO2, for the propylene oxide (PO) reaction, the selectivity towards polypropylene carbonate (PPC) without polyether linkage consistently was >99 %. For the terpolymerization of PO, CO2 and diglycolic anhydride (DGA), a notable epoxide conversion of 86 %, selectively to polycarbonate, with TOF value as high as 36 h−1, was achieved. [ABSTRACT FROM AUTHOR]

This study demonstrates that inclusion of modified starch extrudates as casein and fat replacers in analogue mozzarella cheese array is a statistically echo loom for hydroxypropylation of sorghum and corn starch extrudates involving lesser number of researches than the predictable approach. The hydroxypropylated starches are prepared by using propylene oxide and are found to have DS values between 0.0083 and 0.153, which complied with food grade limit approved by Codex Alimentarius. Inclusion of native and hydroxypropylated corn and sorghum starch extrudates in analogue cheese results in better melt characteristics as compared to their counterpart control cheese. The storage modulus (Gʹ) and loss modulus (Gʹʹ) of analogue cheese increase with the rising frequency. Hydroxypropylated extrudates (HEx) containing cheese is softer and shows elastic behavior. Replacement of casein and fat with native and hydroxypropylated starch extrudates improves the analogue cheese melt and stretch but this strengthening is at the expense of hardness. Inclusion of native and hydroxypropylated starch extrudates permits easy instantaneous replacement of casein by 15% and fat by 10% in analogue mozzarella cheese. This study provides a theoretical guidance for industrialization of analogue cheese with improved rheology, texture, melt, and stretch. [ABSTRACT FROM AUTHOR]

This study explores a novel method of directly epoxidizing hexafluoropropene with molecular oxygen under gaseous conditions using a Cu/HZSM-5 catalytic system (Cu/HZ). An in-depth investigation was conducted on the catalytic performance of Cu-based catalysts on various supports and Cu/HZ catalysts prepared under different conditions. Cu/HZ catalysts exhibited better catalytic performance than other porous medium-supported Cu catalysts for the epoxidation of hexafluoropropene by molecular oxygen. The highest propylene oxide yield of 35.6% was achieved over the Cu/HZ catalyst prepared under conditions of 350 °C with a Cu loading of 1 wt%. By applying characterization techniques including XRD, BET, NH3-TPD, and XPS to different catalyst samples, the relationship between the interaction of Cu2+ and HZSM-5 and the reactivity of the catalyst was studied, thereby elucidating the influence of calcination temperature and loading on the reactivity. Finally, we further proposed the possible mechanism of how isolated Cu2+ and acid sites improve catalytic performance. [ABSTRACT FROM AUTHOR]

The development of efficient heterogeneous catalysts for upgrading CO2, a greenhouse gas, and glycerol (Gly), an untapped biomass resource, into glycerol carbonate (GC) remains a challenge. Herein, 1,8‐diazabicyclo[5.4.0] undec–7–ene (DBU)–based poly (ionic liquid)s (PILs) were constructed for the one–pot synthesis of GC from CO2, Gly, and propylene oxide. Among them, P−DVB−DBUVBI–1 exhibited the best catalytic performance, achieving a GC yield of 90 % under optimal reaction conditions (100 °C, 6 h). The PIL catalyst was easily recovered and reused, as demonstrated by stable activity over five cycles. Density functional theory calculations showed that owing the strong positive charge delocalization ability of DBU onium, DBU–based PILs exhibit high nucleophilicity, which is the key to their efficient catalytic performance in the one–pot reaction. [ABSTRACT FROM AUTHOR]

Mesoionic N‐heterocyclic olefins (mNHOs) have recently emerged as a novel class of highly nucleophilic and super‐basic σ‐donor compounds. Making use of these properties in synthetic polymer chemistry, it is shown that a combination of a specific mNHO and a Mg‐based Lewis acid (magnesium bis(hexamethyldisilazide), Mg(HMDS)2) delivers poly(propylene oxide) in quantitative yields from the polymerization of the corresponding epoxide (0.1 mol% mNHO loading). The initiation mechanism involves monomer activation by the Lewis acid and direct ring‐opening of the monomer by nucleophilic attack of the mNHO, forming a zwitterionic propagating species. Modulation of the mNHO properties is thereby a direct tool to impact initiation efficiency, revealing a sterically unencumbered triazole‐derivative as particularly useful. The joint application of mNHOs together with borane‐type Lewis acids is also outlined, resulting in high conversions and fast polymerization kinetics. Importantly, while molar mass distributions remain relatively broad, indicating faster propagation than initiation, the overall molar masses are significantly lower than found in the case of regular NHOs, underlining the increased nucleophilicity and ensuing improved initiation efficiency of mNHOs. [ABSTRACT FROM AUTHOR]

The hydroxypropyl chitosan (HPCH) and hydroxyethyl chitosan (HECH) are multifunctional chitosan derivatives with biocompatible and biodegradable properties. Due to their hydroxypropyl and hydroxethyl groups, they have water solubility, moisture retention, and gelling properties. In this study, the chitosan derivatives HPCH and HECH were obtained in two steps alkalisation and etherification. For alkalisation, chitosan was kept in an alkaline medium at -18C for 7 days. For etherification; the reaction was carried out for 48 hours by mixing alkaline chitosan with propylene oxide and ethylene oxide separately in a pressure reactor. The structures of the obtained HPCH and HECH were characterised by FT-IR, 1H(13C)-NMR, XRD, and TG analysis methods. Since the degree of deacetylation (DA) of chitosan is 75-85%, the chitosan units contain N-acetyl (-N-(CO)-CH3)) groups in addition to NH2 functional groups. When the 1H(13C)-NMR spectrum of chitosan was examined, the peak value of these acetyl groups was observed at δ1.89 ppm. When the XRD spectra were examined, it was observed that the strong peak in chitosan at 2θ-20° was weakened in HPCH and HECH. In addition, the thermal stability of HPCH and HECH was found to be higher than chitosan in TG analysis. [ABSTRACT FROM AUTHOR]

Surface modification, encompassing both chemical and physical features, plays a crucial role in fulfilling the requirements of biomaterial applications and also improves their performance. Due to that, this study focuses on the optimization of morphology and functionalization of hydroxyapatite (HAP). For this purpose, hydrothermal growth of HAP on (fluorine tin oxide) FTO is carried out in the presence of calcium and phosphate precursors with Ca/P molar ratio of 1.67:1 in the solution. Trisodium nitrilotriacetic acid (NTA) is used as a chelating additive for the first time during hydrothermal process at temperature between 120 and 180 °C for 16–24 h. Further studies on the effect of NTA concentration on HAP formation indicate that hierarchical structures are formed in the presence of NTA with NTA/Ca molar ratio of 1:1 at temperature between 150 and 180 °C for 24 h, improving crystallinity as temperature increasing. To facilitate the functionalization of HAP, the layer deposited at 180 °C with NTA/Ca molar ratio of 1:1 is peeled using two different reagents, Fluoromount™ and polyvinyl alcohol (PVA). The HAP peeled with PVA shows no relevant morphological changes in SEM images, indicating a successful peeling process using PVA. After that, the HAP powders are functionalized with alendronate (AL) molecules and studied using ATR-FTIR, XPS and BET techniques. Chemical shift of PO 4 3− vibrations and appearance of the new peaks assigned to the –NH 2 group demonstrate successful AL-functionalization. The AL-HAP hierarchical structures fabricated with the aid of NTA can be introduced as multifunctional biomaterials for future bio-applications. [Display omitted] [ABSTRACT FROM AUTHOR]

Recently, we applied solution 2H-nuclear magnetic resonance spectroscopy (2H NMR) to analyze the water (deuterium oxide, D2O) structure in several biopolymers at ambient temperature. We established that polymers with good blood compatibility (i.e. poly(2-methoxyethyl acrylate) (PMEA)) have water observed at high magnetic fields (upfield) compared with bulk water. Polymers containing poly(propylene glycol) (PPG) or poly(propylene oxide) (PPO) exhibit good compatibility; however, the reason for this remains unclear. In addition, reports on the blood compatibility of PPO/PPG are limited. Therefore, PPG diester (PPGest) was prepared as a model polymer, and its blood compatibility and water structure were investigated. PPGest exhibited excellent blood compatibility. The water in PPGest was observed upfield by 2H NMR, and it was defined as non-freezing water via differential scanning calorimetry. Based on these observations, the relationship between the blood compatibility and water structure of PPGest is discussed by comparing with those of PMEA, and the reason for the good performance of PPG/PPO-based polymers is discussed. [ABSTRACT FROM AUTHOR]

Copyright of Plastics Science & Technology / Suliao Ke-Ji is the property of Plastics Science & Technology Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)