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The interactions between π-systems in dimers of aromatic molecules lead to particularly stable conformations within the relative orientations of the monomers. Extensive research has been conducted on the properties of these complexes in the neutral state. However, in recent decades, there has been a significant surge in applications harnessing these structures for electrical purposes. Therefore, this study places particular emphasis on a deeper understanding of the redox properties of these compounds and how to modify them. To achieve this, we have focused on modeling the effect of a wide range of functional groups on the redox properties of benzene derivatives, observing a correlation between these properties and the change in the molecular dipole moment. Then, we investigated the effect of π-stacking interactions on these properties in dimers formed by either identical or different monomers. In both cases, there is an enhancement of the reducing character of the systems due to these interactions. Upon oxidation, the charge is distributed proportionally to the redox potential of each monomer. Therefore, if there is heterogeneity in these potentials, the properties of the complete cationic system will be influenced by the monomer with a greater tendency to undergo oxidation. The considered models serve as an excellent example for studying the behavior of nucleobases in DNA or aromatic amino acids, among others. [ABSTRACT FROM AUTHOR]

We present the results for energy landscapes of hexapeptides obtained using interfaces to the Large-scale Atomic/Molecular Massively Parallel Simulator (LAMMPS) program. We have used basin-hopping global optimization and discrete path sampling to explore the landscapes of hexapeptide monomers, dimers, and oligomers containing 10, 100, and 200 monomers modeled using a residue-level coarse-grained potential, Mpipi, implemented in LAMMPS. We find that the dimers of peptides containing amino acid residues that are better at promoting phase separation, such as tyrosine and arginine, have melting peaks at higher temperature in their heat capacity compared to phenylalanine and lysine, respectively. This observation correlates with previous work on the same uncapped hexapeptide monomers modeled using atomistic potential. For oligomers, we compare the variation in monomer conformations with radial distance and observe trends for selected angles calculated for each monomer. The LAMMPS interfaces to the GMIN and OPTIM programs for landscape exploration offer new opportunities to investigate larger systems and provide access to the coarse-grained potentials implemented within LAMMPS. [ABSTRACT FROM AUTHOR]

We explore the large-scale behavior of a stochastic model for nanoparticle growth in an unusual parameter regime. This model encompasses two types of reactions: nucleation, where n monomers aggregate to form a nanoparticle, and growth, where a nanoparticle increases its size by consuming a monomer. Reverse reactions are disregarded. We delve into a previously unexplored parameter regime. Specifically, we consider a scenario where the growth rate of the first newly formed particle is of the same order of magnitude as the nucleation rate, in contrast to the classical scenario where, in the initial stage, nucleation dominates over growth. In this regime, we investigate the final size distribution as the initial number of monomers tends to infinity through extensive simulation studies utilizing state-of-the-art stochastic simulation methods with an efficient implementation and supported by high-performance computing infrastructure. We observe the emergence of a deterministic limit for the particle's final size density. To scale up the initial number of monomers to approximate the magnitudes encountered in real experiments, we introduce a novel approximation process aimed at faster simulation. Remarkably, this approximating process yields a final size distribution that becomes very close to that of the original process when the available monomers approach infinity. Simulations of the approximating process further support the conjecture of the emergence of a deterministic limit. [ABSTRACT FROM AUTHOR]

An accurate description of the long-range (LR) interaction is essential for understanding the collision between cold or ultracold molecules. However, to our best knowledge, there lacks a general approach to construct the intermolecular potential energy surface (IPES) between two arbitrary molecules and/or atoms in the LR region. In this work, we derived analytical expressions of the LR interaction energy, using the multipole expansion of the electrostatic interaction Hamiltonian and the non-degenerate perturbation theory. To make these formulae practical, we also derived the independent Cartesian components of the electrostatic properties, including the multipole moments and polarizabilities, of the monomer for a given symmetry using the properties of these components and the group-theoretical methods. Based on these newly derived formulae, we developed a FORTRAN program, namely ABLRI, which is capable of calculating the interaction energy between two arbitrary monomers both in their non-degenerate electronic ground states at large separations. To test the reliability of this newly developed program, we constructed IPESs for the electronic ground state of H2O–H2 and O2–H systems in the LR region. The interaction energy computed by our program agreed well with the ab initio calculation, which shows the validity of this program. [ABSTRACT FROM AUTHOR]

We study the dynamics of the end monomers of a real chain confined in a spherical cavity to search for a small target on the cavity surface using Langevin dynamics simulation. The results are compared and contrasted with those of a Rouse chain to understand the influence of excluded volume interactions on the search dynamics, as characterized by the first passage time (FPT). We analyze how the mean FPT depends on the cavity size Rb, the target size a, and the degree of confinement quantified by Rg/Rb, with Rg being the polymer radius of gyration in free space. As a basic finding, the equilibrium distribution of the end monomers of a real chain in a closed spherical cavity differs from that of a Rouse chain at a given Rg/Rb, which leads to the differences between the mean FPTs of real and Rouse chains. Fitting the survival probability S(t) by a multi-exponential form, we show that the S(t) of real chains exhibits multiple characteristic times at large Rg/Rb. Our simulation results indicate that the search dynamics of a real chain exhibit three characteristic regimes as a function of Rg/Rb, including the transition from the Markovian to non-Markovian process at Rg/Rb ≈ 0.39, along with two distinct regimes at 0.39 < Rg/Rb < 1.0 and Rg/Rb > 1.0, respectively, where S(t) exhibits a single characteristic time and multiple characteristic times. [ABSTRACT FROM AUTHOR]

Recent experiments by Brückner et al. [Science 380, 1357 (2023)] have observed an anomalous chain length dependence of the time of near approach of widely separated pairs of genomic elements on transcriptionally active chromosomal DNA. In this paper, I suggest that the anomaly may have its roots in internal friction between neighboring segments on the DNA backbone. The basis for this proposal is a model of chain dynamics formulated in terms of a continuum scaled Brownian walk (sBw) of polymerization index N. The sBw is an extension of the simple Brownian walk model widely used in path integral calculations of polymer properties, differing from it in containing an additional parameter H (the Hurst index) that can be tuned to produce varying degrees of correlation between adjacent monomers. A calculation using the sBw of the mean time τc for chain closure predicts—under the Wilemski–Fixman approximation for diffusion-controlled reactions—that at early times, τc varies as the 2/3 power of N, in close agreement with the findings of the Brückner et al. study. Other scaling relations of that study, including those related to the probability of loop formation and the mean square displacements of terminal monomers, are also satisfactorily accounted for by the model. [ABSTRACT FROM AUTHOR]

Borneol is a natural monoterpene with significant applications in various industries, including medicine and perfumery. It presents several diastereomers with different physical and chemical properties, influenced by their unique structures and interactions with molecular receptors. However, a complete description of its inherent structure and solvent interactions remains elusive. Here, we report a detailed investigation of the gas-phase experimental structures of borneol and isoborneol, along with the description of their microsolvation complexes with the common solvents water and dimethyl sulfoxide. The molecules and complexes were studied using chirped-pulse Fourier transform microwave spectroscopy coupled to a supersonic expansion source. Although three rotamers are potentially populated under the conditions of the supersonic expansion, only one of them was observed for each monomer. The examination of the monohydrated complexes revealed structures stabilized by hydrogen bonds and non-covalent C–H⋯O interactions, with water as the hydrogen bond donor. Interestingly, in the clusters with dimethyl sulfoxide, borneol and isoborneol change their roles acting as donors. We further identified a higher-energy rotamer of the borneol monomer in one of the complexes with dimethyl sulfoxide, while that rotamer was missing in the experiment for the monomer. This observation is not common and highlights a specific position in borneol especially favorable for forming stable complexes, which could have implications in the understanding of the unique physical and chemical properties of the diastereomers. [ABSTRACT FROM AUTHOR]

The electronic and vibrational spectra of the meso-tetrakis(4-sulfonatophenyl)-porphyrins (TSPP) have been studied computationally using the PFD-3B functional with time-dependent density functional theory for the excited states. The calculated UV-vis absorption and emission spectra in aqueous solution are in excellent agreement with the experimental measurements of both H2TSPP−4 (monomer) at high pH and H4TSPP−2 (forming J-aggregate) at low pH. Moreover, our calculations reveal an infrared absorption at 1900 cm−1 in the singlet and triplet excited states that is absent in the ground state, which is chosen as a probe for transient IR absorption spectroscopy to investigate the vibrational dynamics of the excited state. Specifically, the S2 to S1 excited state internal conversion process time, the S1 state vibrational relaxation time, and the lifetime of the S1 excited electronic state are all quantitatively deduced. [ABSTRACT FROM AUTHOR]

The simulation of polymer solutions often requires the development of methods that accurately include hydrodynamic interactions. Resolution on the atomistic scale is too computationally expensive to cover mesoscopic time and length scales on which the interesting polymer phenomena are observed. Therefore, coarse-graining methods have to be applied. In this work, the solvent is simulated using the well-established multi-particle collision dynamics scheme, and for the polymer, different coarse-graining methods are employed and compared against the monomer resolved Kremer–Grest model by their resulting diffusion coefficients. This research builds on previous work [Ruiz-Franco et al., J. Chem. Phys. 151, 074902 (2019)], in which star polymers and linear chains in a solvent were simulated and two different coarse-graining methods were developed, in order to increase computational efficiency. The present work extends this approach to ring polymers and seeks to refine one of the authors' proposed model: the penetrable soft colloid model. It was found that both proposed models are not well suited to ring polymers; however, the introduction of a factor to the PSC model delivers satisfying results for the diffusion behavior by regulating the interaction intensity with the solvent. [ABSTRACT FROM AUTHOR]

Synthetic multiblock copolymers are an interesting class of polymeric chains and have emerged as promising materials to mimic the function of complex biomolecules. In this work, we use Wang–Landau sampling to study sequences of multiblock ( A n B n ) m copolymers on the simple cubic lattice, where n represents the block length and m represents the number of blocks. We first compare to the thermodynamic and structural properties of four sequences previously studied in the continuum [W. Wang et al., J. Chem. Phys. 141, 244907 (2014)] to observe the differences that arise during the collapse process. We then focus on the structural transitions that occur at temperatures below the coil-to-globule transition in the lattice. Moreover, by studying additional sequences, we detail the relationship between the block length, number of blocks, and, thus, overall polymer length with respect to said structural transitions. Finally, we observe how the formation and shape of a ground state core of the more strongly interacting monomer type affect the procession of structural changes that occurs as temperature increases. [ABSTRACT FROM AUTHOR]

Ionogels with high fracture strength (16.90 MPa), high Young's modulus (119.97 MPa), high tensile toughness (96.86 MJ m−3), high fracture energy (119.07 kJ m−2) and excellent stretchability (∼1300%) were prepared by varying the ions of solvents. This strategy can be applied to other monomers and ionic liquids, offering a promising way to prepare an ultra-tough ionogel. [ABSTRACT FROM AUTHOR]

In this work, we report a rare ionic covalent organic framework (named as ECUT-iCOF-5) synthesized by the Knoevenagel reaction using an ionic liquid monomer. ECUT-iCOF-5 is found to show a promising potential for gold extraction with a high extraction ability towards gold, including a high extraction capacity (3260 mg g−1), good selectivity over both cations and anions, and good recycle use (at least six times). [ABSTRACT FROM AUTHOR]

To regulate the comprehensive performance of ethylene‐propylene‐diene monomer (EPDM)‐based oil‐absorbing expandable rubber, a series of irradiated α‐olefin‐EPDM7001 rubbers (EOR7001‐X‐Y) are prepared. The influence of the carbon chain length and content of α‐olefins on the structure and properties of the rubber is systematically investigated. Results show that EOR7001‐X‐Y possesses a cross‐linked network structure, and its gel fraction decreases gradually with the increase in carbon chain length and content of α‐olefins. The incorporation of α‐octadecene successfully creates micro‐nanoscale porous structures within the rubber matrix, providing favorable conditions for oil absorption. The introduction of α‐olefins and changes in irradiation dose do not significantly affect the thermal stability of EPDM7001 rubber. The tensile strength slightly reduces, while elongation at break significantly increases, improving the deformation capability. EOR7001‐18‐20 demonstrates exceptional resistance to aging and withstands external forces even after oil absorption. This study supports the development of high‐performance oil‐absorbing expandable rubber. [ABSTRACT FROM AUTHOR]

Motional properties of proteins govern recognition, catalysis, and regulation. The dynamics of tightly interacting residues can form intramolecular dynamic networks, dependencies fine‐tuned by evolution to optimize a plethora of functional aspects. The constructive interaction of residues from different proteins to assemble intermolecular dynamic networks is a similarly likely case but has escaped thorough experimental assessment due to interfering association/dissociation dynamics. Here, we use fast‐MAS solid‐state 15N R1ρ NMR relaxation dispersion aided by molecular‐dynamics simulations to mechanistically assess the hierarchy of individual μs timescale motions arising from a crystal‐crystal contact, in the absence of translational motion. In contrast to the monomer, where particular mutations entail isolated perturbations, specific intermolecular interactions couple the motional properties between distant residues in the same protein. The mechanistic insights obtained from this conceptual work may improve our understanding on how intramolecular allostery can be tuned by intermolecular interactions via assembly of dynamic networks from previously isolated elements. [ABSTRACT FROM AUTHOR]

Comprehensive Summary: Discovery of unprecedented donor‐acceptor patterns can essentially enrich the chemistry of donor‐acceptor cyclopropanes. We herein introduce a concept of vinylogous fluorine stabilizing effect, which guides rational design of a novel donor‐acceptor cyclopropane employing gem‐difluorovinyl group as the electron donor, namely dFVCP. Application of such dFVCPs in a [3+2] cycloaddition with aldehydes and a controlled ring‐opening polymerization by a Mg(OTf)2/DIPEA/C(sp3)‐H initiator system have been demonstrated, providing direct access to fluorine‐containing tetrahydrofurans and all‐carbon main‐chain polymers. [ABSTRACT FROM AUTHOR]

The furan/maleimide Diels–Alder (DA) reaction has been exploited to construct thermally reversible macromolecular structures, such as linear or cross-linked polycondensates, or to cross-link linear polymers, using the free end-type or pending furan and maleimide moieties as the diene and dienophile reagents. Here we report a different approach for the synthesis of homopolymers based on a diol, in which the DA adduct formed by the furan and the maleimide sits within the diol monomer structure. The OH end groups of the diol were used for the synthesis of a polyester and a polyurethane using conventional polycondensation methods and to study their retro DA (rDA) depolymerization through the thermal decomposition of their inner DA adducts. The relevant contribution of this study was however the possibility of synthesizing a copolymer by heating these two polymers together to induce their rDA deconstruction and then lowering the temperature in order to allow the ensuing fragments to recombine statistically by successive DA couplings, thus building the corresponding ester-urethane copolymer. 1H NMR spectroscopy and DSC analysis were employed to confirm the success of this promising approach. [ABSTRACT FROM AUTHOR]

Ceria‐supported vanadium oxide (VOx/CeO2) is an important catalyst for various oxidation reactions. Recently, vanadia has emerged again as a less toxic alternative to CrOx‐based catalysts for the CO2‐assisted oxidative dehydrogenation (ODH) of alkanes. To establish a mechanistic understanding of catalyst regeneration during CO2 exposure, often described as the rate‐limiting step of these reactions, we investigated the regeneration of VOx/CeO2 catalysts with different vanadia loadings using multiple in situ spectroscopies, that is, multi‐wavelength Raman, UV‐Vis, IR and X‐ray photoelectron spectroscopy. Time‐dependent analysis reveals that ceria is only partially regenerated in the bulk but fully regenerated in the subsurface. At the surface, stable carbonates form at vacancies, which are able to regenerate the lattice and deactivate ceria surface oxygen. The VOx/CeO2 samples show a loading‐dependent behavior, with low‐loaded samples regenerating vanadia only partially, due to the high concentration of monomers, while at higher loadings, vanadia can be almost fully regenerated due to the higher nuclearities being thermodynamically more stable. Ceria is regenerated faster than vanadia, indicating that vanadia regenerates by oxygen spill‐over from the ceria lattice. Our results provide important mechanistic insight into CO2 activation over supported vanadia catalysts, which is of great relevance for CO2‐assisted ODH reactions. [ABSTRACT FROM AUTHOR]

Two‐photon lithography (TPL) is a powerful technique for creating 3D microarchitectures. Applied to high‐refractive‐index materials like ZrO2, it promises advanced optics. This is the case of ZrO2 host matrixes in combination with luminescent dopants. However, due to the nonideal crystallinity attained to the TPL pre‐ceramic replica from a custom‐made photoresin, the emission of lanthanide (Ln) dopants in ZrO2 microarchitectures can be suboptimal. However, crystallinity exacerbated by annealing can promote Ln‐emission, thereby enabling the integration of ceramic micro‐optic into a low‐temperature process. This work presents a photoresin containing a metal‐organic monomer tailored for TPL, enabling the fabrication of Ln‐doped tetragonal ZrO2 (t‐ZrO2) microarchitectures. The emission properties of Ln‐doped microarchitectures with trivalent Ln ions (Ln3+), i.e., Yb3+ (2.5 mol%), Er3+ (0.35 mol%), and Tm3+ (0.35 mol%) are studied. The results demonstrate that Ln emission is absent when annealing the microarchitectures at 600 °C. Annealing at 750 °C activates Ln3+ emissions, including 2F5/2–2F7/2 (infrared), 4S3/2–4I15/2 (green), and 3H4–3F6 (near‐infrared) transitions corresponding to Yb, Er, and Tm species. Transmission electron microscopy (TEM) confirms that t‐ZrO2 crystallinity becomes more prominent at 750 °C, demonstrating the promotion of Ln emissions upon thermal treatment and underscoring the role of crystalline in TPL micro‐optical ceramics. [ABSTRACT FROM AUTHOR]

Comprehensive Summary: Discovery of unprecedented donor‐acceptor patterns can essentially enrich the chemistry of donor‐acceptor cyclopropanes. We herein introduce a concept of vinylogous fluorine stabilizing effect, which guides rational design of a novel donor‐acceptor cyclopropane employing gem‐difluorovinyl group as the electron donor, namely dFVCP. Application of such dFVCPs in a [3+2] cycloaddition with aldehydes and a controlled ring‐opening polymerization by a Mg(OTf)2/DIPEA/C(sp3)‐H initiator system have been demonstrated, providing direct access to fluorine‐containing tetrahydrofurans and all‐carbon main‐chain polymers. [ABSTRACT FROM AUTHOR]

The copolymerization of two or more monomers produces polymeric materials with unique properties that cannot be achieved with homopolymers. However, precise control over the polymer sequence remains challenging because the sequence is determined by the inherent reactivity of comonomers. Therefore, only limited methods using modified monomers or supramolecular interactions are reported. In this study, the sequence control of acrylate‐styrene copolymerization using multinuclear zinc complexes is reported. The copolymerization of the zinc acrylate complex with a polymeric sheet‐like structure and styrene in benzene affords a copolymer with a higher content of acrylate triad than calculated for the statistical random model, whereas tetranuclear zinc acrylate (TZA) affords a copolymer with fewer adjacent acrylate sequences. The copolymer with a higher content of acrylate triad exhibits a lower glass transition temperature because of the higher mobility of the longer polystyrene segments. These results highlight the promise of multinuclear zinc acrylate complexes as monomers for sequence‐controlled copolymerization. [ABSTRACT FROM AUTHOR]

Positively charged nanofiltration membranes have attracted much attention in the field of lithium extraction from salt lakes due to their excellent ability to separate mono‐ and multi‐valent cations. However, the thicker selective layer and the lower affinity for Li+ result in lower separation efficiency of the membranes. Here, PEI‐P membranes with highly efficient Li+/Mg2+ separation performance are prepared by introducing highly lithophilic 4,7,10‐Trioxygen‐1,13‐tridecanediamine (DCA) on the surface of PEI‐TMC membranes using a post‐modification method. Characterization and experimental results show that the utilization of the DCA‐TMC crosslinked structure as a space‐confined layer to inhibit the diffusion of the monomer not only increases the positive charge density of the membrane but also reduces its thickness by ≈35% and presents a unique coffee‐ring structure, which ensures excellent water permeability and rejection of Mg2+. The ion–dipole interaction of the ether chains with Li+ facilitates Li+ transport and improves the Li+/Mg2+ selectivity (SLi,Mg = 23.3). In a three‐stage nanofiltration process for treating simulated salt lake water, the PEI‐P membrane can reduce the Mg2+/Li+ ratio of the salt lake by 400‐fold and produce Li2CO3 with a purity of more than 99.5%, demonstrating its potential application in lithium extraction from salt lakes. [ABSTRACT FROM AUTHOR]

This article reports the synthesis of a novel perfluoropolyalkylether (PFPAE) vinylether monomer and its use as a comonomer in the thiol‐ene photopolymerization of a trifunctional thiol together with a trifunctional vinylether. The crosslinked copolymers are obtained in the form of few mm thick layers and characterized. By changing the thiol/ene ratio, the polymers are optimized to tailor their surface composition and obtain adhesion between two thick layers despite the presence of the fluorinated monomer. The final bilayered structures are adhesive, and appeared chemically resistant, with good dimensional stability: therefore, these fluorinated thiol–ene based copolymers are likely to be of interest for applications based on layer‐by‐layer processes, such as additive manufacturing and microfluidics. [ABSTRACT FROM AUTHOR]

Depolymerization and subsequent capture of monomers is of interest for process efficiency and sustainability. Polyamide‐6 (PA‐6) can be depolymerized in aqueous solution using a homogeneous catalyst. To purify the ε‐caprolactam (CPL) monomer and recycle the catalyst, two potential crystallization‐based strategies are studied: direct crystallization from the reaction mixture and liquid‐liquid extraction prior to crystallization. Solubilities in water and promising organic solvents were measured and compared to predictions using perturbed‐chain statistical associating fluid theory (PC‐SAFT) or conductor‐like screening model for real solvents (COSMO‐RS). Detailed solid‐liquid equilibria (SLE) of the CPL/water system were investigated utilizing DSC and PXRD. This work provides an overview of important factors of PA‐6 depolymerization including recycling of tungstophosphoric acid (TPA) and purification of CPL monomers. A first conceptual process design to be further developed is derived. [ABSTRACT FROM AUTHOR]

ABSTRACT An autofluorescent inclusion (AFI) specifically accumulated in mesophyll cells (MCs) of non‐salt‐secretor mangrove was found to be related to salt, but its biosynthesis and spatial distribution characteristics remain unclear. Here, Kandelia obovata served as the experimental material, and the composition of AFI was identified as condensed tannin (CT). Na contents increased in purified AFIs under NaCl treatment, while Na+ efflux in MCs was lower than the control. In vitro, Na+ addition caused aggregations of AFIs. Proteins related to Na+/H+ and vesicle transport were identified in the purified AFIs by liquid chromatography‐mass spectrometry. TEM images revealed the structures involved in CT biosynthesis in chloroplasts and CT accretions in vacuoles were more visible under higher salinity. Spatial metabolomics analysis on flavonoid metabolites involving in CT biosynthesis illustrated those flavonoids and three CT monomers were positively related to salt in MCs. Real‐time quantitative PCR verified the genes encoding enzymes for CT biosynthesis were upregulated accordingly. Taken together, CT biosynthesis is positively correlated with Na accumulation in leaves. The CTs synthesized in chloroplasts are transported as shuttles to vacuole via cytoplasm, facilitating the sequestration and compartmentalization of excessive Na+ ions into the vacuole, which confers non‐salt‐secretor mangrove K. obovata a higher salt tolerance. [ABSTRACT FROM AUTHOR]

Human calcitonin (hCT) is an endogenous polypeptide commonly employed in treating bone resorption-related illnesses, but its clinical application is limited due to its high aggregation tendency. Metalloporphyrins are effective in suppressing amyloid fibrillation, positioning them as potential drug candidates for amyloidogenic disorders like Alzheimer's and type 2 diabetes. In this work, we investigated the effects of Fe(III) meso-tetra(4-sulfonatophenyl)porphine chloride (FeTPPS), a highly efficient ONOO− decomposition catalyst, on hCT aggregation. Our findings reveal that FeTPPS effectively precludes hCT fibrillation by stabilizing the monomers and delaying the structural transition from α-helix bundles to β-sheet-rich aggregates. The macrocyclic ring of FeTPPS plays a significant role in disrupting hCT self-associations. Among various porphyrin analogs, those with an iron center and negatively charged peripheral substituents exhibit a stronger inhibitory effect on hCT aggregation. Spectroscopic analyses and computational simulations indicate that FeTPPS binds to hCT's core aggregation region via complexation with His20 in a 1 : 1 molar ratio. Hydrophobic interaction, hydrogen bonding, and π–π stacking with the residues involving Tyr12, Phe19, and Ala26 also contribute to the interactions. Collectively, our study provides a promising approach for developing novel hCT drug formulations and offers theoretical guidance for designing metalloporphyrin-based inhibitors for various amyloidosis conditions. [ABSTRACT FROM AUTHOR]

The durability of anion exchange membranes (AEMs) and the balance between ionic conductivity and dimensional stability have been the focus of research. To this end, we propose a new type of AEMs with vinyl imidazole as the in situ cross‐linking monomer. The rigid‐flexible balance within the membrane was adjusted by changing the arrangement of the internal segments of the polymer and introducing different monomers into the main chain. The results showed that the performance of AEMs could be effectively improved by adopting an ether‐free backbone and a cationic cross‐linking strategy. The swelling rate of all AEMs was less than 20%. The ionic conductivity of BDCP‐80 reached 102.74 mS cm−1 at 80°C. Alkaline stability tests showed that the ionic conductivity of all AEMs remained above 82% after 720 h immersion in 2 M NaOH solution at 80°C. This study demonstrated that the simple in situ cross‐linking method can effectively improve the overall performance of AEMs and provide an effective way to develop high‐performance AEMs. [ABSTRACT FROM AUTHOR]

HIV-1 capsid protein (CA) is essential for viral replication and interacts with numerous host factors to facilitate successful infection. Thus, CA is an integral target for the study of virus-host dynamics and therapeutic development. The multifaceted functions of CA stem from the ability of CA to assemble into distinct structural components that come together to form the mature capsid core. Each structural component, including monomers, pentamers, and hexamers, presents a variety of solvent-accessible surfaces. However, the structure-function relationships of these components that facilitate replication and virus-host interactions have yet to be fully elucidated. A major challenge is the genetic fragility of CA, which precludes the use of many common methods. To overcome these constraints, we identified CA-targeting aptamers with binding specificity for either the mature CA hexamer lattice alone or both the CA hexamer lattice and soluble CA hexamer. To enable utilization of these aptamers as molecular tools for the study of CA structure-function relationships in cells, understanding the higher-order structures of these aptamers is required. While our initial work on a subset of aptamers included predictive and qualitative biochemical characterizations that provided insight into aptamer secondary structures, these approaches were insufficient for determining more complex non-canonical architectures. Here, we further clarify aptamer structural motifs using focused, quantitative biophysical approaches, primarily through the use of multi-effective spectroscopic methods and thermodynamic analyses. Aptamer L15.20.1 displayed particularly strong, unambiguous indications of stable RNA G-quadruplex (rG4) formation under physiological conditions in a region of the aptamer also previously shown to be necessary for CA-aptamer interactions. Non-canonical structures, such as the rG4, have distinct chemical signatures and interfaces that may support downstream applications without the need for complex modifications or labels that may negatively affect aptamer folding. Thus, aptamer representative L15.20.1, containing a putative rG4 in a region likely required for aptamer binding to CA with probable function under cellular conditions, may be a particularly useful tool for the study of HIV-1 CA. [ABSTRACT FROM AUTHOR]

Herein, a photoinduced method is introduced for the synthesis of highly cross‐linked and uniform polymer microspheres by atom transfer radical polymerization (ATRP) at room temperature and in the absence of stabilizers or surfactants. Uniform particles are obtained at monomer concentrations as high as 10% (by volume), with polymers being exempt from contamination by residual transition metal catalysts, thereby overcoming the two major longstanding problems associated with thermally initiated ATRP‐mediated precipitation polymerization. Moreover, the obtained particles have also immobilized ATRP initiators on their surface, which directly enables the controlled growth of densely grafted polymer layers with adjustable thickness and a well‐defined chemical composition. The method is then employed successfully for the synthesis of molecularly imprinted polymer microspheres. [ABSTRACT FROM AUTHOR]

Glistening is the condensation of water that forms within the intraocular lens (IOL) materials. In this study, a new approach was attempted to reduce the glistening of IOL materials by introducing hydrophobic acrylic monomers with different alkyl side chain lengths into the IOL materials. Various hydrophobic acrylic monomers such as butyl acrylate (BA), 2‐ethylhexyl acrylate (EHA), and dodecyl acrylate (DA) were copolymerized with a hydrophobic acrylic monomer, 2‐phenoxyethyl acrylate, respectively. In this process, we investigated the effect of the alkyl side chain lengths of hydrophobic acrylic monomers on the glistening of hydrophobic acrylic IOL materials. As the content of hydrophobic acrylic monomers (BA, EHA, and DA) increased, the glistening of IOL materials decreased significantly for all hydrophobic acrylic monomers. At the same content of hydrophobic acrylic monomers, the IOL material showed the least content of glistening when copolymerized with DA. However, the IOL material obtained using BA exhibited the largest content of glistening, indicating that the glistening reduction effect was large in the order of DA>EHA>BA. These findings show that the glistening of IOL materials decreases with increasing alkyl side chain lengths of hydrophobic acrylic monomers. [ABSTRACT FROM AUTHOR]

Conformational ensemble generation and the search for the global minimum conformation are important problems in computational chemistry. In this work, a variant on the conformer‐rotamer ensemble sampling tool (CREST) iterative metadynamics (iMTD) algorithm designed for determining structural ensembles and energetics of noncovalent clusters of flexible molecules is presented. We term this new algorithm a low‐energy diversity‐enhanced variant on CREST, or LEDE‐CREST. As with CREST, the energies are evaluated using the semiempirical GFN2‐xTB extended tight binding approach. The utility of the algorithm is highlighted by generating ensembles for a variety of noncovalent clusters of flexible or rigid monomers using both CREST and LEDE‐CREST. [ABSTRACT FROM AUTHOR]

Dual response polyurethane nanocapsules consisting of a hydrophilic core are synthesized via interfacial polyaddition of the diisocyanate monomers and different diols (VA‐060 and glycols) in inverse miniemulsion process. The presence of the water‐soluble NIR dye in the core and azo‐bonds in the polymer shell allows the selective release of encapsulated material triggered by temperature or NIR light. The capsules are characterized by transmission electron microscopy (TEM) and dynamic light scattering (DLS). The capsule degradation under external stimuli, like temperature and NIR light, is confirmed microscopically by TEM. Macroscopic evidence of the capsule cleavage was achieved by the incorporation of the chemical into the capsule core, and subsequent treatment of the capsules with NIR laser in the presence of the suitable reagent outside the capsules. A color‐forming chemical reaction occurred after the shell opening. The reactions were easily detected by visual observation of a color change and by UV–Vis spectroscopy. [ABSTRACT FROM AUTHOR]

Covering: up to 2024 This review aims to draw a parallel between all known oligomers of monoterpene indole alkaloids (MIAs) by illustrating the chemical logic underlying their assembly. For this purpose, oligomeric MIAs were first comprehensively listed and organized according to the names of the backbones of their constitutive monomers and the binding sites. From this extensive list, an oligomer network was generated and unprecedented MIA statistics were mined and shared herein. Subsequently, oligomeric MIAs were categorized according to the number of connections instigated between their monomeric components (single, double, triple, and mixed tethering), then subdivided according to the uniqueness or combination of oligomerization assembly reactions. This effort outlined oligomerization trends in a scaffold-specific manner, and established binding reactivity patterns facilitating the comprehension of the associated biosynthetic processes. At last, this review illustrates a unique initiative in crafting a comprehensive repository of machine-readable metadata for MIA oligomers that could be leveraged for chemoinformatic purposes. [ABSTRACT FROM AUTHOR]

Endo-norbornene derivatives are much cheaper and more accessible. However, it is difficult to prepare endo-polynorbornenes with ultra-high molecular weight (UHMW) by ring opening metathesis polymerization (ROMP) owing to the low activity. The molecular weight of poly(endo-NB-2OH)n could only reach to 309.1 kg mol−1 for 24 h via ROMP. While, UHMW poly(endo-NB-2OH)m was prepared by combining ROMP and acyclic metathesis reaction in much shorter time. The effects of residual monomer, amount of H2SO4, concentration, temperature and reaction time were investigated in depth. The UHMW P(endo-NB-2OH)m (Mn=2645.5 kg mol−1, PDI = 1.74) could be obtained at 80 °C for 5 min with H2SO4/G3 as 10/1 and concentration of 0.1 M. Moreover, UHMW P(endo-NBI-OH)m(Mn=1114.2 kg mol−1, PDI = 1.95) was also successfully prepared by this method. However, the H2SO4/G3 should increase to 30/1, and reacted for 45 min owing to the steric resistance of the cyclic dicarboximide. For P(exo-NBI-OH)n with lower activity, reaction time should prolong to 3 h to obtain UHMW P(exo-NBI-OH)m(Mn=1716.7 kg mol−1, PDI = 1.93). Finally, UHMW P(endo-NB-2alkyne)m, P(endo-NBI-alkyne)m, and P(exo-NBI-alkyne)m were successfully prepared via post-modification. Acyclic metathesis reaction is a robust and universal reaction to prepare other functional UHMW polynorbornenes, especially for the UHMW endo-polynorbornenes, which could not be prepared by ROMP efficiently. [ABSTRACT FROM AUTHOR]

Hydrogen bonds (H-bonds) are the most essential non-covalent interactions in nature, playing a crucial role in stabilizing the secondary structures of proteins. Taking inspiration from nature, researchers have developed several multiple H-bonds crosslinked supramolecular polymer materials through the incorporation of H-bond side-chain units into the polymer chains. N-acryloyl glycinamide (NAGA) is a monomer with dual amides in the side group, which facilitates the formation of multiple dense intermolecular H-bonds within poly(N-acryloyl glycinamide) (PNAGA), thereby exhibiting diverse properties dependent on concentration and meeting various requirements across different applications. Moreover, numerous attempts have been undertaken to synthesize diverse NAGA-derived units through meticulous chemical structure regulation and fabricate corresponding H-bonding crosslinked supramolecular polymer materials. Despite this, the systematic clarification of the impact of chemical structures of side moieties on intermolecular associations and material performances remains lacking. The present review will focus on the design principle for synthesizing NAGA-derived H-bond side-chain units and provide an overview of the recent advancements in multiple H-bonds crosslinked PNAGA-derived supramolecular polymer materials, which can be categorized into three groups based on the chemical structure of H-bonds units: (1) monomers with solely cooperative H-bonds; (2) monomers with synergistic H-bonds and other physical interactions; and (3) diol chain extenders with cooperative H-bonds. The significance of subtle structural variations in these NAGA-derived units, enabling the fabrication of hydrogen-bonded supramolecular polymer materials with significantly diverse performances, will be emphasized. Moreover, the extensive applications of multiple H-bonds crosslinked supramolecular polymer materials will be elucidated. [ABSTRACT FROM AUTHOR]

Catalytic DNA has gained significant attention in recent decades as a highly efficient and tunable catalyst, thanks to its flexible structures, exceptional specificity, and ease of optimization. Despite being composed of just four monomers, DNA's complex conformational intricacies enable a wide range of nuanced functions, including scaffolding, electrocatalysis, enantioselectivity, and mechano-electro spin coupling. DNA catalysts, ranging from traditional DNAzymes to innovative DNAzyme hybrids, highlight the remarkable potential of DNA in catalysis. Recent advancements in spectroscopic techniques have deepened our mechanistic understanding of catalytic DNA, paving the way for rational structural optimization. This review will summarize the latest studies on the performance and optimization of traditional DNAzymes and provide an in-depth analysis of DNAzyme hybrid catalysts and their unique and promising properties. [ABSTRACT FROM AUTHOR]

By means of molecular dynamics computer simulation, the conformational space of polyampholyte macromolecules with various distributions of the charged groups along the chain is studied. A coarse‐grained model where each monomer unit of the chain is presented as a non‐charged group in the backbone of the macromolecule connected with a charged side pendant is considered. A limiting case of fully charged chains in the isoelectric point is investigated. The oppositely charged monomer units are distributed in various patterns: regular alternating, multiblock, or random sequences. It is found that the chains with random unit distribution adopt much more compacted conformations than the chains with regular distributions with comparable block lengths. Calculating the chain size and its fluctuation along with the spatial density distribution, coil, and globular conformations are distinguished and arranged on the diagrams in terms of chain length, block length, and Bjerrum length. [ABSTRACT FROM AUTHOR]

Current families of reversible photochemical reactions present challenges for light‐controlled polymers of either photostationary states, which are common in photoinduced cycloaddition/cycloreversion reactions, or exclusively intramolecular bond changes, which characterize most photochromic units. In response to these challenges, here the concept of "proximal photocleavage" is presented, which combines photochemical crosslinking with a photocleavable linker, enabling a one‐time bond formation/cleavage sequence. Proximal photocleavage methacrylate monomers comprising, in series along the pendant of the methacrylate, a coumarin unit for crosslinking and either a phenacyl or ortho‐nitrobenzyl photocleavable group for decrosslinking are reported. The photophysical properties of these monomers and their statistical copolymers with methyl methacrylate are described, and wavelength selective crosslinking and de‐crosslinking of thin polymer films are demonstrated. [ABSTRACT FROM AUTHOR]

Vanillyl alcohol has emerged as a widely used building block for the development of biobased monomers. More specifically, the cationic (photo‐)polymerization of the respective diglycidyl ether (DGEVA) is known to produce materials of outstanding thermomechanical performance. Generally, chain transfer agents (CTAs) are of interest in cationic resins not only because they lead to more homogeneous polymer networks but also because they strikingly improve the polymerization speed. Herein, the aim is to compare the cationic chain‐growth photopolymerization with the thermally initiated anionic step‐growth polymerization, with and without the addition of CTAs. Indeed, CTAs lead to faster polymerization reactions as well as the formation of more homogeneous networks, especially in the case of the thermal anionic step‐growth polymerization. Resulting from curing above the TG of the respective anionic step‐growth polymer, materials with outstanding tensile toughness (>5 MJ cm−3) are obtained that result in the manufacture of potential shape‐memory polymers. [ABSTRACT FROM AUTHOR]

A new aluminum complex (NSO)AlMe2 featuring a hydrogen bond donor on the ligand backbone has been synthesized via the reaction of AlMe3 with 1-((2-(isopropylamino)phenyl)thio)propan-2-ol (NSO-H) and spectroscopically characterized. In the complex, the aluminum atom is in a distorted tetrahedral coordination sphere determined by the anionic oxygen and neutral nitrogen atoms of the ligand and by the two carbon atoms of the alkyl groups. After proper activation, the complex (NSO)AlMe2 was able to promote the ring-opening polymerization of L-, rac-lactide, ε-caprolactone and rac-β-butyrolactone. The polymerization of rac-lactide was faster than that of L-lactide: in a toluene solution at 80 °C, the high monomer conversion of 100 equivalents was achieved in 1.5 h, reaching a turnover frequency of 63 molLA·molAl–1·h–1. The experimental molecular weights of the obtained polymers were close to those calculated, assuming the growth of one polymer chain for one added alcohol equivalent and the polydispersity indexes were monomodal and narrow. The kinetic investigation of the polymerization led to the determination of the apparent propagation constants and the Gibbs free energies of activation for the reaction; the terminal groups of the polymers were also identified. The complex (NSO)AlMe2 was active in harsh conditions such as at a very low concentration or in the melt using technical-grade rac-lactide. A relatively high level of activity was observed in the ring-opening polymerization of ε-caprolactone and rac-β-butyrolactone. DFT calculations were performed and revealed the central role of the NH function of the coordinated ligand. Acting as a hydrogen bond donor, it docks the monomer in the proximity of the metal center and activates it toward the nucleophilic attack of the growing polymer chain. [ABSTRACT FROM AUTHOR]

Smart microgels have gained much attention because of their wide range of applications in the field of biomedical, environmental, nanotechnological and catalysis sciences. Most of the applications of microgels are strongly affected by their morphology, size and size distribution. Various methodologies have been adopted to obtain polymer microgel particles. Droplet microfluidic techniques have been widely reported for the fabrication of highly monodisperse microgel particles to be used for various applications. Monodisperse microgel particles of required size and morphology can be achieved via droplet microfluidic techniques by simple polymerization of monomers in the presence of suitable crosslinker or by gelation of high molecular weight polymers. This report gives recent research progress in fabrication, characterization, properties and applications of microgel particles synthesized by microfluidic methods. [ABSTRACT FROM AUTHOR]

Nanochannel membranes are promising materials for enantioselective sensing. However, it is difficult to make a compromise between the selectivity and permeability in traditional nanochannel membranes. Therefore, new types of nanochannel membranes with high enantioselectivity and excellent permeability should be explored for chiral analysis. Here, asymmetric catalysis strategy is reported for interfacial polymerization synthesis of chiral covalent‐organic framework (cCOF) nanochannel membrane for enantioselective sensing. Chiral phenylethylamine (S/R‐PEA) and 2,4,6‐triformylphloroglucinol (TP) are used to prepare chiral TP monomer. 4,4′,4″‐triaminotriphenylamine (TAPA) is then condensed with chiral TP to obtain cCOF nanochannel membrane via a C═N Schiff‐base reaction. The molar ratio of TP to S/R‐PEA is adjusted so that S/R‐PEA is bound to the aldehyde only or both the aldehyde and hydroxyl groups on TP to obtain chiral‐induced COF (cCOF‐1) or both chiral‐induced and modified COF (cCOF‐2) nanochannel membrane, respectively. The prepared cCOF‐2 nanochannel membrane showed two times more selectivity for limonene enantiomers than cCOF‐1 nanochannel membrane. Furthermore, cCOF‐2 nanochannel platform exhibited excellent sensing performance for other chiral molecules such as limonene, propanediol, methylbutyric acid, ibuprofen, and naproxen (limits of detection of 19–42 ng L−1, enantiomer excess of 63.6–86.3%). This work provides a promising way to develop cCOF‐based nanochannel enantioselective sensor. [ABSTRACT FROM AUTHOR]

In this study, electrochemical copolymerization of 6,7-diphenyl-4,9-di(selenophen-2-yl)-[1,2,5]thiadiazolo[3,4-g]quinoxaline and 3,3'-didecyl-3,4-propylenedioxythiophene is carried out to obtain a copolymer namely poly(6,7-diphenyl-4,9-di(selenophen-2-yl)-[1,2,5]thiadiazolo[3,4-g]quinoxaline-co-3,3'-didecyl-3,4-propylenedioxythiophene). Two distinct copolymers, PC1 and PC2, were produced as a result of the utilization of two different feed ratios. Copolymers were examined electrochemically and spectroelectrochemically after the copolymerization procedure. This study's major goal is to combine the exceptional characteristics of homopolymers P1 and P2 (P1 has a low band gap but is not soluble, and P2 is soluble and has a larger band gap) into a single copolymeric material. [ABSTRACT FROM AUTHOR]

Novel Fe N C electrocatalysts derived from conjugated microporous polymers based on pre-functionalization of monomers was developed, which exhibits great potential for cathodic oxygen reduction reaction in fuel cell and provides a feasible strategy of developing multi-atoms doping catalysts for heterogeneous catalysis. [Display omitted] Porous iron–nitrogen-doped carbons (Fe N C) offer a great platform for construction of cathodic oxygen reduction reaction (ORR) catalysts in fuel cells. However, challenges still remain regarding with the collapse of carbon-skeleton during pyrolysis, uneven distribution of active sites and aggregation of metal atoms. In this work, we synthesized Fe, N co-doped conjugated microporous polymer (FeN-CMP) through a facile bottom-up strategy using 1,3,5-triethynylbenzene and iron-chelated 3,8-dibromo-1,10-phenanthroline as monomers, ensuring the uniform coordination of N with Fe element in network. Then, the resulting FeN-CMP was treated by pyrolysis without structural collapse to obtain porous Fe N C electrocatalyst for ORR. The most active catalyst was fabricated under 900 °C, which exhibits remarkable ORR activity in alkaline medium with half-wave potential of 0.796 V (18 mV and 105 mV positive deviation from the commercial Pt/C catalyst and post-doping catalyst), high selectivity with nearly 4e- transfer process and excellent methanol tolerance. Our study first developed porous Fe N C electrocatalysts derived from Fe, N -anchoring CMPs based on pre-functionalization of monomers, which exhibits great potential as an alternative to commercial Pt/C catalyst for ORR, and provides a feasible strategy of developing multi-atoms doping catalysts for energy storage and conversion as well as heterogeneous catalysis. [ABSTRACT FROM AUTHOR]

Silicone hydrogels are pivotal materials used in contact lenses, biomedicine, and electronic devices, where oxygen permeability and equilibrium water content (EWC) are essential attributes. Generally, an increase in silicone content boosts oxygen permeability but diminishes EWC, presenting a notable trade‐off challenge. In this study, a solvent incorporation method that significantly elevates oxygen permeability without markedly affecting EWC is introduced. Among various solvents, isopropanol incorporation notably enhances oxygen permeability (101 barrer) while maintaining an EWC of 56.0%. This improvement is attributed to enhanced connectivity within the silicone network. Additionally, it is discovered that incorporating siloxane nanoparticles (SNPs) further increases the connectivity of the silicone network, offering a more pronounced improvement in oxygen permeability than solvent alone. However, excessive SNP addition can lead to large phase separation, resulting in decreased transmittance, lower EWC, and increased mechanical strength. Optimizing a transmittance of over 99%, SNP addition achieves a silicone hydrogel with an oxygen permeability of 125 barrer and an EWC of 49.5%, surpassing many advancements reported in the literature. [ABSTRACT FROM AUTHOR]

The development of polymer carriers for systems of prolonged and controlled release of substances, particularly drugs, into the action environment is a relevant task in polymer chemistry and technology. This aims to solve the problem of reducing the effective dose of a medical drug administered into the body of a person or animal. The latest achievements in the field of creating such carriers in the form of spherical particles based on 2- hydroxyethyl methacrylate and polyvinylpyrrolidone (co)polymers are analyzed and summarized. The working principles and advantages of such systems are described. The research of the synthesis regularities, structure, properties and perspectives of application of granular hydrogels based on 2-hydroxyethyl methacrylate and its copolymers with polyvinylpyrrolidone was analyzed. The mixture of decanol and cyclohexanol as a solvent for the monomer phase is substantiated. Based on the analysis of kinetic studies, the optimal technological parameters for the suspension polymerization of 2-hydroxyethyl methacrylate with polyvinylpyrrolidone were selected, and the possibility of regulating the dispersion characteristics of copolymers via changes in the technological synthesis modes was confirmed. The results of studies on the sorption-desorption properties of copolymers concerning model substances and drugs are described. The possibility of directed regulation of sorption capacity and drug release rate through changes in copolymer composition was confirmed. Methods for increasing the sorption capacity of hydrogels for drugs are proposed. [ABSTRACT FROM AUTHOR]

Medium chain‐length polyhydroxyalkanoates (mcl‐PHAs) are efficiently synthesized from fatty acids. It was hypothesized that under non‐axenic conditions, the anti‐microbial properties of fatty acids would reduce growth of microbial competitors and allow Pseudomonas putida LS46 to dominate the population resulting in non‐sterile mcl‐PHA production. Non‐sterile batch and fed‐batch cultures produced similar final mcl‐PHA content, monomer composition, and productivity during 24–27 h cultivations when compared to sterile control cultures for initial octanoic acid concentrations ranging from 5 to 40 mM at an initial pH of 6.5. In the absence of a P. putida inoculum, growth was eventually observed in non‐sterile medium after a lag period of up to 120 h, the length of which was dependent on the octanoic acid concentration. The efficacy of prolonged non‐sterile cultivation was tested using a sequential batch reactor (SBR). After 28 days (672 h), 1.62 g L−1 of total biomass was observed, of which the mcl‐PHA content was 47%. This resulted in a PHA titer of 0.77 g L−1, and a volumetric PHA productivity of 32 mg L−1 h−1. The polymer composition remained stable throughout at 87.0 ± 2.7% C8 monomers, and short‐chain length (scl‐) monomers were not detected. This study is the first of its kind to report that purely mcl‐PHAs were produced after prolonged periods in a non‐sterile environment and demonstrate that medium chain‐length fatty acids exert a strong selective pressure toward organisms that synthesize mcl‐PHA. This suggests an opportunity for mcl‐PHA production in open continuous cultivation, which could reduce both fixed and operating costs. [ABSTRACT FROM AUTHOR]

Low‐strain cyclic olefin monomers, including five‐membered, six‐membered, eight‐membered, and macrocyclic rings, have been recently exploited for the synthesis of depolymerizable polyolefins via ring‐opening metathesis polymerization (ROMP). Such polyolefins can undergo ring‐closing metathesis depolymerization (RCMD) to regenerate their original monomers. Nevertheless, the depolymerization behavior of polyolefins prepared by ROMP of seven‐membered cyclic olefins, an important class of low‐strain rings, still remains unexplored. In this study, we demonstrate the chemical recycling of polyheptenamers to cycloheptene under standard RCMD conditions. Highly efficient depolymerization of polyheptenamer was enabled by Grubbs' second‐generation catalyst in toluene. It was observed that the monomer yields increased when the depolymerization temperature increased and the starting polymer concentration was reduced. A near‐quantitative monomer regeneration (>96%) was achieved within 1 h under dilute conditions (20 mM of olefins) at 60°C. Moreover, polyheptenamer exhibited a decomposition temperature above 430°C, highlighting its potential as a new class of thermally stable and chemically recyclable polymer materials. [ABSTRACT FROM AUTHOR]

The control of the regioselectivity of metal‐catalyzed α‐olefins polymerization is of everlasting interest. Most nickel and palladium catalysts show high regioselectivity involving 2,1‐insertion of α‐olefins and 1,ω‐enchainment chain‐straightening, especially α‐diimine nickel catalysts. In this contribution, we report extremely rare regioselective chain‐straightening polymerization of α‐olefins through 2,ω‐enchainment using unsymmetrical amine–imine nickel catalysts. The polymerizations of α‐olefins (1‐hexene, 1‐octene, and 1‐decene) were studied in detail, and the effects of catalyst structure, reaction temperature, and monomer concentration on the polymerization activity and the regioselectivity were examined. The unsymmetrical N‐substituents of the amine–imine nickel catalysts play a crucial role in the regioselectivity. High regioselectivity involving 80.4% 1,2‐insertion and 84.5% 2,ω‐enchainment is realized to produce amorphous polyolefins without melting temperatures. [ABSTRACT FROM AUTHOR]

Fluorosilicone rubber is essential for sealing in extreme temperatures and non‐polar environments due to its exceptional adaptability. However, achieving a high yield of fluorosilicone polymers with medium and high fluorine content remains a challenge. Herein, a facile gradient strategy is developed that involves modifying the method of cyclic monomer addition based on the rate of ring‐opening polymerization (ROP), to improve yield and adjust fluorine content precisely. The polymerization process is designed and tailored based on the reaction rates of anionic ring‐opening polymerization (AROP) and cationic ring‐opening polymerization (CROP) via an efficient gradient strategy. The effects of the polymerization process on the viscosity and yield of vinyl fluorosilicone polymers and hydrofluorosilicone polymers are investigated and optimized. Notably, the as‐prepared vinyl‐terminated fluoromethylsilane with 60% fluorine content (FMS‐Vi‐60F) has a high yield (86.6%) and high viscosity (150 000 mPa·s) in a short reaction time, which is superior to previous methods. Clearly, the gradient ring‐opening method developed in this work provides a facile and efficient synthesis for fabricating fluorosilicone polymers with a high yield and tunable fluorine content. [ABSTRACT FROM AUTHOR]

AbstractUtilizing the Matlab platform, two-dimensional diffusion-limited aggregation and three-dimensional diffusion-limited cluster aggregation models were established to simulate the hydrophobic flocculation of coal particles. The formation process of flocs aggregated by monomer particles and small groups was simulated from both plane and space perspectives. The gyration radius fractal dimension increased from 1.401 to 1.539 in the DLA model and from 1.623 to 1.729 in the DLCA model, indicating that the floc morphology gradually stabilized and the structure became increasingly regular during the hydrophobic flocculation process. The porosity of DLA increased from 0.762 to 0.851, indicating that the dendritic structure of flocs formed a spatial shielding effect on the planar structure, which prevented the particles from entering the flocs. In contrast, the porosity of DLCA first increased from 0.506 to 0.611 and then decreased, stabilizing at approximately 0.53, indicating that small groups filled the internal voids of flocs in the spatial structure, leading to a gradual increase in floc density. The surface fractal dimension and density of flocs were calculated using the surface fractal and hydrostatic sedimentation-terminal velocity theories, respectively, confirming the conclusions drawn from the simulation analysis. [ABSTRACT FROM AUTHOR]