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The structure of mRNA lipid nanoparticles (LNPs) is still under debate, with different studies presenting varying morphological characteristics, significantly hindering their biomedical potential. A typical formulation process of mRNA LNPs involves three steps: initial rapid mixing of lipids in an ethanol phase and mRNA in an acidic aqueous phase, followed by the swift removal of ethanol, and finally adjusting the solution to a neutral environment. In this study, we utilize Small Angle Neutron Scattering (SANS) with contrast matching to reveal the kinetic pathway-dependent of mRNA LNPs morphology. We find that the formulation process of the Moderna COVID-19 vaccine is controlled by a competition between aggregation and microphase separation, dictating the diverse morphologies observed in mRNA LNPs. The first step leads to the formation of polydisperse spherical droplets with an average diameter of 42±6.0 nm in an acidic ethanol aqueous solution. Ethanol removal initiates both aggregation and internal microphase separation, resulting in a polydisperse core-shell structure with an average diameter of 48±3.7 nm. Heptadecan-9-yl 8-((2-hydroxyethyl) (6-oxo-6-(undecyloxy) hexyl) amino) octanoate (SM-102) binds to mRNA via electrostatic interaction to form a reverse-wormlike micelle structure inside. The 1,2-Distearoyl-sn‑glycero-3-phosphocholine (DSPC) and PEG-lipid are just in the shell and cholesterol acting as a filler throughout the core-shell structure. Upon transitioning to a neutral environment, SM-102 loses its charge and neither the periphery nor the reverse-wormlike micelle can maintain their stabilities, leading to further aggregation and microphase separation. The average diameter of core-shell structure turns to be 66±5.2 nm. In the actual formulation process of the Moderna COVID-19 vaccine, steps 2 and 3 occur simultaneously, and the competition between aggregation and microphase separation determines the final morphology. These findings offer crucial insights into optimizing the morphology of mRNA LNPs, thereby facilitating advancements in vaccine development and mRNA vaccine delivery technologies.

Anode modification and optimization is crucial towards improving performance of organic solar cells (OSCs). PEDOT:PSS is the most common choice as a hole transport layer (HTL) material, but suffers from issues including low conductivity. In this work, three alkyl amine derivatives - methylamine hydrochloride (MA), ethylamine hydrochloride (EA) and propylamine hydrochloride (PA) are doped into the commercially available Al 4083 PEDOT:PSS to form PEDOT:PSS-MA, PEDOT:PSS-EA and PEDOT:PSS-PA, as modified HTLs. All these modified HTLs exhibit improved chemical and electrical properties including work functions (WF), conductivities and charge carrier motilities. The alkyl amine doping shows compatibility in both Small Molecular Acceptors and All-Polymer OSCs. With PEDOT:PSS-MA demonstrates a highest PCE of 18.49 % compared to the 17.84 % of OSC devices prepared with pristine PEDOT:PSS with the PM6:L8-BO system, while PM6:PY-IT all-polymer OSCs improve PCE from 14.53 % to 15.22 %. AFM characterizations reveal that the introduction of the dopants have smoothened the surface morphology of spin-coated HTL films, which contributes towards more efficient charge extraction. In summary, this study not only presents a method of improving OSC efficiencies, but also provides insight and further possible directions towards anode optimization of OSCs.

Covalent Organic Frameworks (COFs) have emerged as highly promising materials for the photocatalytic production of hydrogen peroxide (H₂O₂) due to their exceptional structural tunability, robust frameworks, and high porosity. The efficient overall photosynthesis of H₂O₂ hinges on the simultaneous occurrence of the oxygen reduction reaction (ORR) and water oxidation reaction (WOR). This review introduces recent progress in developing key approaches such as backbone engineering and the incorporation of side groups to facilitate these critical reaction pathways. For example, innovative COF designs, such as spatially separating redox centers, have demonstrated significant improvements in photocatalytic performance. Moreover, the introduction of thioether-decorated triazine-based COFs and hexavalent triphenylene knots has led to remarkable H₂O₂ production rates. Furthermore, this review also addresses the challenges associated with the practical implementation of COFs, including their stability under operational conditions and the necessity for innovative reactor designs. The future prospects of COFs in sustainable chemical synthesis are also discussed, emphasizing their potential for COFs to revolutionize H₂O₂ production through green and sustainable methodologies. This review aims to provide valuable insights into the design and development of high-performance COF photocatalysts, paving the way for their practical applications in the sustainable production of value-added chemicals.

The polymer gels containing dynamic cross-links and mesogenic groups are among the key candidates for the development of soft actuators and detectors, displays, sensors and other programmable and self-healing materials. In this article, firstly, the collapse of polymer networks with irreversible cross-links in the presence of a dynamic cross-linker is investigated by means of Flory-type theory. It is shown that, at not a very poor solvent quality (near the theta-conditions), the swelling ratio for a gel containing irreversible and dynamic cross-links is less than for a gel with irreversible cross-links only, whereas at poor or good solvent qualities sizes of these gels are close to each other. The number of dynamic cross-links monotonically increases with worsening the solvent quality. The gel contraction can be also achieved by increasing the dynamic cross-linker concentration, which allows one to change the transition point in a wide range of solvent conditions. Secondly, polymer networks containing irreversible and dynamic cross-links and incorporating mesogenic side groups is studied using the Maier–Saupe theory. With decreasing in the temperature, the continuous transition from a swollen to collapsed state occurs. With further increase in the temperature, the swelling ratio discontinuously decreases and the nematic order parameter sharply increases from zero to a value ​​close to one. By increasing the dynamic cross-linker concentration, the swelling-to-collapse transition and, then, the isotropic-nematic transition are observed. A phase diagram of the gel is constructed and, depending on the dynamic cross-linker concentration and temperature, the swollen gel with the zero nematic order parameter, the collapsed gel with the zero nematic order parameter, and the collapsed gel with the nematic ordering can be formed. A growth of the length of the mesogenic side group leads to an increase in the area of ​​existence of the collapsed gel with the nematic ordering in the phase diagram. The obtained theoretical results are in agreement with corresponding experimental data from the literature.

Organic photovoltaic materials have been widely used in organic solar cells (OSCs) and organic photodetectors (OPDs) systems, owing to their numerous advantages such as low cost, light weight, high structural tunability, and ease of solution processing. Among these materials, near-infrared (NIR)-responsive materials, especially those with NIR II-region (1000–1700 nm) response, are crucial in the construction of tandem OSCs and semitransparent OSCs to achieve high power conversion efficiency and high light utilization efficiency, respectively. Meanwhile, OPDs with NIR II-region response show great application potential in industrial, military, and medical fields. In recent years, some progress has been made in the development of organic photovoltaic materials and devices with NIR II-region response. This review provides an overview of the design strategies for NIR organic photovoltaic materials, followed by a classification and summary of representative organic NIR II-region responsive materials and their performance in OSCs and OPDs. Lastly, we conclude with an outlook on the development of organic photovoltaic materials with NIR II-region response.

This work reports the effect of 1–5 wt% epoxidized soybean oil (ESO) addition on the thermal, mechanical, and morphological properties of polybutylene succinate (PBS). ESO acts as a chain extender as well as a mild plasticizer of PBS. N-methylimidazole (NMI) is used as a catalyst to promote the reaction between PBS and ESO, and thermal, rheological, and spectroscopic analyses demonstrate increased viscoelastic properties, compatibility, crystallinity and thermal stability of the melt reacted formulations. In the presence of NMI, storage modulus (G’) values two orders of magnitude higher than that of pure PBS are achieved, confirming the completion of the chain extension reaction. A drastic refinement of the biphasic structure of the blend is observed, with the formation of a homogenous structure where ESO is well incorporated into the matrix. Finally, tensile tests reveal enhanced mechanical performance in the blends reacted in the presence of NMI. These findings pave the way for the development of a versatile family of materials which could find potential application in sustainable biodegradable packaging.

Cholesteric liquid crystals, also known as chiral nematics, possess a right-angle helicoidal structure with pitch in the submicrometer and micrometer range. Although the possibility of getting optical reorientation in this kind of materials has been considered since the discovery of giant optical nonlinearity in nematic liquid crystals, a significant light-induced modulation of the helical structure has shown to be a challenging task. The recent experimental realization of a chiral phase with an oblique helicoidal structure, identified as the heliconical phase predicted by Meyer and DeGennes in 1968, offers the opportunity to observe such an optical reorientation of the optic axis. This paper is a brief review of the nonlinear optical properties of these unconventional chiral nematic liquid crystals and is aimed at showing that the world of liquid crystalline phases can still amaze with new material properties and new physics.

Liquid crystal (LC) phases have been used in various self-assembly technologies owing to their stimuli-responsive characteristics. Especially, orientation-controlled LC structures on and in surfaces are extensively studied in physics, chemistry, and materials science because they can be used in patterning applications beyond the conventional LC display. The key idea in recent development is to control the surface anchoring condition between the substrate and LC materials. Specifically, defects in the LC phases have been introduced as an effective lithographic tool for fabricating distinguished patterns. In this review, the bulk and surface-induced structures of LC materials are overviewed to show the relationship between the surface characteristics of the substrates and the elastic properties of LC materials. The two main themes are (1) orientation control, which can be achieved by micro- and nano-confinement using solid and fluid substrates, and (2) the application of LC materials as optoelectronics and sensors. Finally, the review discusses the defect structures of LC materials fabricated on flexible substrates and their possible applications.

Ternary organic solar cells (OSCs) are the feasible and efficient strategy to achieve the high-performance OSCs. It is of great significance to develop a superior third component candidate for constructing efficient ternary OSCs. In this work, we intelligently designed and synthesized a dimerized small molecule donor by connecting two asymmetric small molecule donors with the vinyl group, which is named DSMD-βV. This innovative oligomeric molecule DSMD-βV not only exhibits the complementary absorption and the cascade energy level arrangement with PM6 and BTP-eC9, but also regulates the phase separation micromorphology based on PM6:BTP-eC9. Consequently, PM6:DSMD-βV:BTP-eC9 based ternary device exhibits the improved exciton dissociation, charge transport and decreased recombination, thus achieving a superior power conversion efficiency (PCE) of 18.26 %, surpassing PM6:BTP-eC9 based binary (17.63 %). This work indicates that the dimerized small molecule donor is able to become a promising third component candidate, which also opens up a unique idea for the construction of efficient ternary organic solar cells.