Synthesis and Characterization of Branched Mesogen-Jacketed Liquid Crystal Polymers Based on 2,5-Bis[(4‘-methoxyphenyl)oxycarbonyl]styrene and 4-Chloromethylstyrene

A series of branched mesogen-jacketed liquid crystal polymers were synthesized via atom transfer radical copolymerization of mesogenic 2,5-bis[(4‘-methoxyphenyl)oxycarbonyl]styrene (MPCS) and nonmesogenic 4-chloromethylstyrene (CMS) catalyzed by the CuCl/CuCl2/bipyridine complex in anisole solution at 110 °C. During the early period of polymerization, CMS acted mainly as an initiator to induce the polymerization of MPCS. The molecular weights (MWs) of the resultant polymers increased linearly with monomer conversion and showed a symmetrical and relatively narrow distribution. With the proceeding of polymerization, MWs changed from monomodal to multimodal distribution, indicating the formation of branched structure through the action of vinyl group of CMS. This mechanism was also supported by the increased chain density estimated by a combination of gel permeation chromatography and laser light scattering, end-group analysis, and the reactivity ratios of two monomers (rMPCS = 0.71, rCMS = 0.10). The thermotropic properties of the copolymers strongly relied on the feed ratio of MPCS to CMS and MW. The feed ratio of MPCS to CMS should be at least 30 with high enough MW. For the copolymer obtained at the feed ratio of 32, the minimum Mn,GPC was 1.21 × 104 Da to achieve a mesophase. Although linear poly{2,5-bis[(4‘-methoxyphenyl)oxycarbonyl]styrene} displayed columnar nematic phase (ΦN) and hexatic columnar nematic phase (ΦHN) depending on MW, the branched polymer showed just a ΦN phase, indicating the remarkable depressing effect of the branched structure on the mesomorphic property

Long-Range Chirality Transfer in Free Radical Polymerization of Bulky Vinyl Monomers Containing Laterally Attached <i>p</i>-Terphenyl Groups

Two series of chiral bulky vinyl monomers, 2-(4′-hexyloxyphenyl)-5-(4′-alkoxycarbonylphenyl)styrene and 2-(4′-alkoxycarbonylphenyl)-5-(4′-hexyloxyphenyl)styrene (abbreviated as S-(+)-HexMm/R-(−)-HexM0 and S-(+)-MmHex/R-(−)-M0Hex (m = 0, 1, 2, 3), respectively), were designed and synthesized. The former differed the latter only by the relative location of vinyl group, i.e., orientation against or toward the stereocenter. Except for S-(+)-HexM1 and S-(+)-HexM3, all the monomers readily underwent radical polymerization to yield the polymers displaying optical rotations and Cotton effects in the UV−vis absorption region of side groups distinct to the corresponding model compounds and mononmers, implying the formation of main chain chirality, most probable helicity. The influences of the configuration, the distance to p-terphenyl, and the position relative to vinyl group of stereocenter on the chiroptical properties of the resultant polymers were systematically studied. It was found that inverting the absolute spatial configuration of asymmetric center or changing the parity of methylene number between stereocenter and p-terphenyl alternated the direction of optical rotation of polymer, similar to the odd−even alternation behavior observed in the cholesteric phase of achiral 2,5-bis(4′-hexyloxyphenyl)styrene doped with the corresponding monomers. This parallel indicated an identical driving force for the formation of chiral mesophase and the asymmetric secondary structure of the polymer. When the spatial configuration of stereocenter was fixed, its distance to p-terphenyl rather than vinyl group played a dominant role in the induction of an excess helical sense. However, the stereogenic center at the ortho position of vinyl group exhibited a larger induction power than those at the meta position

Tuning the Helicity of Self-Assembled Structure of a Sugar-Based Organogelator by the Proper Choice of Cooling Rate

A novel sugar-appended low-molecular-mass gelator, 4′′-butoxy-4-hydroxy-p-terphenyl-β-d-glucoside (BHTG), was synthesized. It formed thermally reversible gels in a variety of aqueous and organic solvents. Three-dimensional networks made up of helical ribbons were observed in the mixture of H2O/1,4-dioxane (40/60 v/v). The handedness of the ribbons depended on the rate of gel formation. Fast-cooling process led to right-handed ribbons, while slow-cooling process led to left-handed ones. A combinatory analyses of microscopic, spectroscopic, and diffraction techniques revealed that BHTG formed a twisted interdigitated bilayer structure with a d spacing of 3.1 nm in gels through a kinetically controlled nucleation−growth process. There were two kinds of molecular orientations of BHTG in the nuclei, clockwise and anticlockwise, which dictated the growth of ribbons. One was metastable and formed first during the cooling process of gel formation. It was able to gradually transform into the more stable latter one with further decreasing temperature. Fast-cooling process did not leave enough time for the nuclei to evolve from metastable to stable state and the ribbons grown from them exhibited right-handedness. However, the metastable nuclei transformed into the stable one when cooled slowly and directed the molecules of BHTG to grow into left-handed aggregates

Data_Sheet_1_Analyzing the Impact of Greenhouse Planting Strategy and Plant Architecture on Tomato Plant Physiology and Estimated Dry Matter.docx

Determine the level of significance of planting strategy and plant architecture and how they affect plant physiology and dry matter accumulation within greenhouses is essential to actual greenhouse plant management and breeding. We thus analyzed four planting strategies (plant spacing, furrow distance, row orientation, planting pattern) and eight different plant architectural traits (internode length, leaf azimuth angle, leaf elevation angle, leaf length, leaflet curve, leaflet elevation, leaflet number/area ratio, leaflet length/width ratio) with the same plant leaf area using a formerly developed functional–structural model for a Chinese Liaoshen-solar greenhouse and tomato plant, which used to simulate the plant physiology of light interception, temperature, stomatal conductance, photosynthesis, and dry matter. Our study led to the conclusion that the planting strategies have a more significant impact overall on plant radiation, temperature, photosynthesis, and dry matter compared to plant architecture changes. According to our findings, increasing the plant spacing will have the most significant impact to increase light interception. E–W orientation has better total light interception but yet weaker light uniformity. Changes in planting patterns have limited influence on the overall canopy physiology. Increasing the plant leaflet area by leaflet N/A ratio from what we could observe for a rose the total dry matter by 6.6%, which is significantly better than all the other plant architecture traits. An ideal tomato plant architecture which combined all the above optimal architectural traits was also designed to provide guidance on phenotypic traits selection of breeding process. The combined analysis approach described herein established the causal relationship between investigated traits, which could directly apply to provide management and breeding insights on other plant species with different solar greenhouse structures.</p

How the Si–O–Si Covalent Bond Interface Affects the Electrochemical Performance of the Silicon Anode

Nano-Si can alleviate the structural damage caused by volume expansion while ensuring high reversible lithium storage capacity. However, the abundant specific surface area and unique unbonded electronic properties at the surface of the nanoparticles make them suffer from complex surface side reactions and an agglomeration phenomenon. Here, strategies based on surface modification are developed to enhance the performance of nano-Si anodes. Through the in situ grafting of the SiOC coating, a stable and high-energy Si–O–Si covalent bond is formed between the core–shell, making the core–shell as a whole and avoiding the formation of dead silicon. In addition, it was verified by experiments and density functional theoretical calculations that the introduction of the covalent bond redistributed the electrons on the nano-Si surface, and the interface composed of electron-less silicon and electron-rich oxygen elements ensured high adsorption capacity to the electrolyte and structural stability after the introduction of lithium ions, thus ensuring efficient cycling capacity

Odd−Even Effect in Free Radical Polymerization of Optically Active 2,5-Bis[(4‘-alkoxycarbonyl)- phenyl]styrene

Odd−Even Effect in Free Radical Polymerization of Optically Active 2,5-Bis[(4‘-alkoxycarbonyl)- phenyl]styren

Architected Si/C Micro–Nanostructures with Air Cushion-Inspired Stress Mitigation Strategies for Lithium-Ion Battery Anodes

Silicon/carbon (Si/C) composites have emerged as promising anode materials for next-generation lithium-ion batteries (LIBs) due to their high power and energy density, but managing the stress resulting from the large volume change of Si during charging and discharging remains a major challenge. To address this issue, we present a novel microsized porous Si/C-based anode design (AC_Si/C) that incorporates Si@C core–shell nanoparticles and hollow carbon nanospheres as deformable cushions fabricated using a scalable microemulsion approach. Our hybrid anode material system offers high ion and electron conductivity and efficient stress mitigation via the deformable hollow carbon nanospheres, resulting in improved cycling and rate performance. Finite element simulations reveal the stress mitigation mechanisms of the hollow carbon nanospheres, and the AC_Si/C nanostructure exhibits a high reversible specific capacity (855.3 mA h g–1 at 2 A g–1 over 500 cycles) and good capacity reservation for rate performance tests under various current densities. The microemulsion-based synthesis method enables large-scale production of porous Si/C nanocomposites as high-performance commercial anode material systems, demonstrating the potential of this air cushion-inspired design for the development of next-generation high-performance LIBs

Chiroptical and Thermotropic Properties of Helical Styrenic Polymers: Effect of Achiral Group

Six novel chiral bulky styrenic monomers, (+)-2-[4′-((<i>S</i>)-2″-methylbutyloxy)­phenyl]-5-phenylstyrene <b>(A-1)</b>, (+)-2-[4′-((<i>S</i>)-2″-methylbutyloxy)­phenyl]-5-(4′-fluorophenyl)­styrene <b>(A-2)</b>, (+)-2-[4′-((<i>S</i>)-2″-methylbutyloxy)­phenyl]-5-(4′-<i>tert</i>-butylphenyl)­styrene <b>(A-3)</b>, (+)-2-phenyl-5-[4′-((<i>S</i>)-2″-methylbutyloxy)­phenyl]­styrene <b>(B-1)</b>, (+)-2-(4′-fluorophenyl)-5-[4′-((<i>S</i>)-2″-methylbutyloxy)­phenyl]­styrene <b>(B-2)</b>, and (+)-2-(4′-<i>tert</i>-butylphenyl)-5-[4′-((<i>S</i>)-2″-methylbutyloxy)­phenyl]­styrene <b>(B-3)</b>, were synthesized and radically polymerized to yield the corresponding polymers, <b>PA-1</b>–<b>PA-3</b> and <b>PB-1</b>–<b>PB-3</b>. All of them consisted of laterally attached <i>p-</i>terphenyl pendants terminated by an identical (+)-(<i>S</i>)-2-methylbutyloxy end and an achiral end with various size. The first three differed the others by the position of vinyl group relative to chiral motifs. Evidenced by the results of NMR, polarimetry, circular dichroism spectroscopy, computer simulation, thermal properties, and X-ray diffractions, the chiral <i>p</i>-alkoxyphenyl group <i>ortho</i> to the vinyl group induced the helical conformation of polymer backbone with an excess screw sense as in <b>PA-1</b>–<b>PA-3</b>, whereas that <i>meta</i> to the vinyl group failed to dictate the growth of polymer backbone. The achiral end of the side group had a great effect on the optical rotation of polymer. The specific optical rotation of <b>PA-3</b> that bore tertiary butyl groups was over 3 times larger than <b>PA-1</b> and <b>PA-2</b> terminated with hydrogen and fluorine atoms. Accompanied by the existence of helical structure with a predominant screw sense, stable liquid crystalline phases were generated by <b>PA-1</b>–<b>PA-3</b> at above glass transition temperatures but not by <b>PB-1</b>–<b>PB-3</b>. An unusual glass transition temperature and structure relationship was also revealed

Synthesis and Characterization of Near-Infrared Absorbing and Fluorescent Liquid-Crystal Chromophores

This work demonstrates that the donor−acceptor−donor charge-transfer chromophores can be tailor-made to be near-infrared absorbing and fluorescent, as well as being liquid crystals. The chromophore containing an extremely strong acceptor of benzo[1,2-c:4,5-c′]bis([1,2,5]thiadiazole) can form a columnar mesophase that absorbs at 890 nm and emits at 1160 nm in the solid state. These chromophores are readily soluble in common organic solvents and can form thin films by casting or spin coating, making them suitable for further device applications

Kill Two Birds with One Stone: Multifunctional Porous SiOC–Fe₂O₃ Composite for Li Ion Energy Conversion and Electromagnetic Wave Absorption

It is necessary to design a scalable composite material with a rational structure for Li-ion batteries and electromagnetic wave absorption. Herein, we developed a modified precursor-driven method of spacer-assisted oxidation to prepare heterogeneous multi-interface SiOC-based composite ceramic nanoparticles. The outstanding structural design regulated by the ratio of raw materials tailored its functional potential in the fields of Li-ion batteries and electromagnetic wave absorption. The addition of a small amount of iron-sol produced small-sized ceramic nanoparticles bridged by carbon ribbons, which can provide efficient charge transfer kinetics and volumetric buffering capacity. Used in Li-ion battery anodes, it exhibited a specific discharge capacity of 514.4 mAh/g after 1000 cycles at a current density of 0.5 A/g with durable long cycling performance. In addition, the addition of high iron-sol induced the formation of porous core–shell nanoparticles and performed excellent electromagnetic wave absorption ability. The ceramic nanoparticles with carbon content of about 30% had the lowest reflection loss in the X-band of −55.5 dB, and the effective absorption range was 8.48–12.4 GHz, which basically covered the entire X-band. This strategy enriches the preparation and application of multifunctional composite ceramic nanoparticles