Molecular Systems Design & Engineering最新文献

The separation capacity of a column typically remains constant. By applying stimuli-responsive materials to the stationary phase, the separation capacity in a single column can be tuned; however, the separation mode is not completely switched. In this study, we aimed to develop a cation/anion-exchange mode switching chromatography approach, in which the monomer ratio is adjusted, enabling the surface charge to become either negative or positive in response to mobile phase pH. Three types of beads were prepared, each modified with a pH-responsive mixed-charge polymer combining a cationic monomer, a pH-responsive carboxylic acid monomer, a neutral monomer, and a cross-linking monomer. The composition ratio of the cationic monomer to the pH-responsive carboxylic acid monomer was set at 1 : 2 so that the cation-exchange mode occurs at a pH above the pK_a and the anion-exchange mode occurs below the pK_a. At a pH below the pK_a, the retention factor of the negatively charged compound increased. In contrast, at a pH above the pK_a, the retention factor of the positively charged compound increased, confirming the charge switching on the bead surface. Switching to the cation- and anion-exchange mode enabled the separation of five basic antidepressants and acidic non-steroidal anti-inflammatory drugs, respectively. Utilizing a pH-responsive mixed-charge polymer, we attributed a cation/anion-exchange mode to a single column.

Polyurethane (PU) materials have been widely used for developing microcapsules due to their excellent polymerization, encapsulation, and controlled release properties. These unique properties endow PU-based microcapsules with desired functions for enhanced oil recovery (EOR). However, there are some special requirements for PU-based microcapsules in their application of the EOR process, such as they are expected to exhibit good stability at room temperature but thermo-responsive swelling-release properties in the oil reservoir. To enhance the functionality of PU-based microcapsules for EOR, after validating the swelling-release behaviors of PU-based microcapsules, we employed all-atom molecular dynamics (MD) simulations to study the effects of molecular structure of PU-based polymers on thermo-responsivity of microcapsules. The simulation results demonstrate that the diisocyanate segments have significant influence on swelling behaviors of PUs. The different diisocyanate segments, including isophorone diisocyanate (IPDI), toluene diisocyanate (TDI), 4,4′-diphenylmethane diisocyanate (MDI), and hexamethylene diisocyanate (HDI), have different impacts on the flexibility of the polymer, which further influence the network structure of the polymer matrix. The different swelling behaviors of PU-based polymers were further analyzed from energetic and kinetic perspectives, and it is demonstrated that TDI–PU can combine stability and thermo-responsivity together. In addition, the introduction of anionic functional groups can further facilitate the swelling process. The findings in this study serve as a foundation for future studies toward the development of polymer flooding technology and provide valuable molecular insights into the swelling mechanism of PU-based polymers.

The emerging perovskite solar cells (PSCs) have been explored as the most promising photovoltaic technology in the past decade, with the sharp increase of the power conversion efficiency (PCE) from 3.8% to certified 26.1%, comparable to that of crystalline silicon solar cells. Compared to conventional PSCs, inverted PSCs show attractive advantages, such as high device stability, negligible hysteresis and excellent compatibility with flexible and tandem devices. Self-assembled monolayers (SAMs) have been considered as one of the most promising hole-transporting materials (HTMs) for inverted PSCs owing to their low costs and material consumption and simple device fabrication with high PCEs. This review summarizes the recent developments in highly efficient SAMs as HTMs for inverted PSCs. On the basis of the anchoring group, three categories of SAMs are identified and discussed: SAMs with phosphonic acid, SAMs with carboxylic acid, and SAMs based on other anchoring groups. Finally, a future outlook of SAMs for high-performance inverted PSCs is provided. We hope that this review will be useful for the further design of SAMs toward the eventual commercialization of PSCs.

An in-depth understanding of corrosion inhibitor behaviour(s) at the metal–solution interface governed by unique molecular features is the key premise to realising molecular tailoring for pronounced metal protection. This study investigated the distinct adsorption behaviours induced by merely replacing the chemical functionality upon benzothiazole, i.e., 2-mercaptobenzothiazole (2-MBT) and 2-aminobenzothiazole (2-ABT), towards electro-galvanised steel (ZE) corrosion using both experimental and theoretical approaches. Electrochemical results confirm that both inhibitor candidates act as corrosion inhibitors for ZE in NaCl solution. The underlying interactions of the inhibitor molecule with the targeting metal, dissolved metal ions and corrosion products were explored by means of X-ray photoelectron spectroscopy, focused ion beam scanning electron microscopy and Raman spectroscopy. It is suggested that 2-MBT facilitates the precipitation upon the ZE by complexing with the released Zn²⁺ in solution, while 2-ABT promotes preferentially thin inhibitor film formation initiated by chemisorption. Density functional theory (DFT) reveals that at high concentrations the molecules tend to adsorb vertically (slightly tilted) at the surface, where the presented heteroatoms enhance surface–molecule interaction. In addition, DFT suggests that the strong binding strength of 2-MBT could facilitate the formation of complexes with displaced Zn. Based on the proposed mechanisms, the adsorption stability upon polarised ZE surfaces was determined, which reveals that 2-MBT forms a thick inhibitor layer at a relatively high polarisation state, whereas 2-ABT dissociates from the surface with the increasing value of surface overpotential. The findings of this study provide structural understanding that underpins inhibitor tailoring and molecular design to achieve the desired inhibition properties.

A crucial challenge in using organo-metal complexes for photocatalytic organic reactions is the need to develop applications of homogeneous photocatalysts that can effectively function under visible light conditions. For the first time, the use of binuclear complexes containing ferrocenyl-hydrazides as a ligand and nickel or copper as central metals as homogeneous photocatalysts in the oxidation of organic compounds is presented. The new organometal photocatalysts were prepared and identified using techniques, such as FT-IR spectroscopy, NMR spectroscopy, XRD, XRF, XPS, SEM, TGA, EDX, UV-visible, and photocurrent measurements. The oxidation of benzylic C(sp³)–H bonds to produce oxygenated molecules and the selective conversion of C–C double bonds to benzaldehyde can be achieved using bis-ferrocenyl hydrazide complexes with electron-withdrawing or electron-donating groups on the hydrazide moiety under visible-light irradiation in an air atmosphere, at ambient temperature and without the need for external oxidants. The synthesized complexes also can be used to oxygenate 1H-indole to 1H-indole-2,3-dione. The investigation of the role of donating and withdrawing functional groups in the synthesized complexes for selected oxidation reactions is a significant benefit of this report. It was found that only the [(FcHz)₂Ni] and [(FcHz)₂Cu] complexes without functional groups were able to provide a suitable response in the oxidation of the compounds. Additionally, the theoretical DFT and TD-DFT methodologies enabled us to describe the photocatalytic oxidation behavior of these metal complexes. The calculations showed conformational changes in the structure of metal complexes after oxidation. The molecular orbital and natural transition orbital analyses revealed the nature of electronic transitions in the UV-visible absorption bands.

Detection of cortisol (Cort), a stress hormone, is essential in monitoring chronic and mental health stress. As such, there is growing interest in the development of cortisol molecularly imprinted polymers (MIPs) as molecular receptors for sensor development. Of the cortisol MIPs described in the literature, the optimization of the functional monomers has been through trial-and-error experimentation. Through a computational approach, the number of optimization experiments can be reduced, which is time efficient and cost effective, while reducing chemical wastage. In addition to density functional theory (DFT) calculations, this study used an atomistic molecular dynamics simulation approach that resembles that of the real-life experimental methods to elucidate the compatibility of template-monomer-crosslinkers-solvent for cortisol MIP receptors that can efficiently recognize and capture cortisol from biological fluids. The functional monomer investigated were 4-vinylpyridine (4VP), acrylic acid (AA), acrylamide (AM), glycidyl methacrylate (GMA), 2-hydroxyethyl methacrylate (HEMA) and methylacrylic acid (MAA) with ethylene glycol dimethacrylate (EGDMA) as the crosslinker. The intermolecular hydrogen bonds and the template-monomer binding energies obtained through DFT suggested Cort-MAA as the most stable complex both in the gas phase and solution. Considering the calculated solvent energies, acetonitrile was recommended as a porogenic solvent. Through molecular dynamics simulation, various parameters were analyzed to explain the compatibility of the functional monomer with the cortisol template in the MIP development. From blend analysis of template-monomer, Cort-4VP was found to be the most miscible complex. For template-monomer-crosslinker (EGDMA), the mean square displacement (MSD) and diffusion coefficient analyses indicated 1 : 2 (cortisol/monomer) as the ratio in which the complexes are most stable. The highest peaks observed from the Radial distribution function were for Cort-MAA and Cort-AA at 1 : 4 indicating better interactions of the functional monomers with the Cort. Investigating the effect of solvents for template-monomer-crosslinker-solvent, the lowest MSD was at 1 : 4 with three complexes having the lowest values for solubility parameters at 1 : 4 confirming this ratio to be generally suitable for the composition of cortisol MIPs pre-polymerization.

Amphiphilic molecules spontaneously form self-assembly structures depending on physical conditions such as the molecular structure, concentration, and temperature. These structures exhibit various functionalities according to their morphology. The critical packing parameter (CPP) is used to correlate self-organized structures with the chemical composition. However, accurately calculating it requires information about both the molecular shape and molecular aggregates, making it challenging to apply directly in molecular design. We aimed to predict the self-assembled structure of a molecule directly from its chemical structure and to analyze the factors influencing it using machine learning. Dissipative particle dynamics simulations were used to reproduce many self-assembly structures comprising various chemical structures, and their CPPs were calculated. Machine learning models were built using the chemical structures as input data and the CPPs as output data. As a result, both random forest and the gated recurrent unit showed high prediction accuracy. Feature importance analysis and sample size dependence revealed that the amphiphilic nature of molecules significantly influences the self-assembly structures. Additionally, selecting an appropriate molecular structure representation for each algorithm is crucial. The study results should contribute to product development in the fields of materials science, materials chemistry, and medical materials.

Water-harvesting polymer materials have the potential to create new sources of potable water. However, a holistic understanding of the relationship between polymer structure and water-harvesting properties is lacking compared to studies on specific materials. In this work, we synthesised a library of methacrylic acid-co-poly(ethylene glycol) methyl ether methacrylate)-based hydrogels (poly(MAA-co-PEGMA)) with directed modifications, including composition, crosslinker lengths, crosslinking density and preparation of the hydrogels. MAA serves as a hygroscopic monomer while PEGMA provides hydrophilicity and thermoresponsive properties. The water uptake and release capabilities of all materials was also assessed. The optimised composition of the copolymer (75 : 5 : 20 MAA : EGDMA : PEGMA, mole%) has a water uptake of 98 mg g⁻¹ polymer at 60% RH after 24 hours. The poly(MAA-co-PEGMA) materials also show a capability for water release, showing no significant decrease in water uptake capacity after repeated uptake-release cycles. Minimum temperatures for water release could easily be adjusted with polymer composition, ranging from 50–70 °C. The data presented in this body of work serves as a foundation for future efforts in creating thermoresponsive, water-harvesting polymers with real-world applications.

A facile and eco-friendly synthetic strategy has been developed to achieve a series of hydrogen bonding-rich bio-based thermosetting resins in this study. Using both safe and green solvents, we successfully synthesized target bio-based bisbenzoxazines (DcTa-fa, DcTa-sa, and DcTa-da) with high purity from five different naturally resourced raw materials. The chemical structures of the obtained bisbenzoxazine monomers were verified by nuclear magnetic resonance technology (including ¹H and ¹³C NMR, two-dimensional ¹H–¹H nuclear Overhauser effect spectroscopy (NOESY), and ¹H–¹³C heteronuclear multiple quantum coherence (HMQC)) and Fourier transform infrared spectroscopy (FT-IR). The polymerization processes were systematically investigated by differential scanning calorimetry (DSC) and in situ FT-IR analysis. Contact angle measurements were conducted and the corresponding results revealed tunable surface properties during the polymerization process of each bio-based bisbenzoxazine resin. In order to understand the relationship between the chemical structure and surface properties, more detailed FT-IR analyses were carried out to investigate the hydrogen bonding networks in the resulting polybenzoxazines. Notably, poly(DcTa-fa) presented excellent thermal stability (T_d10 of 377 °C, Y_c of 53.7 wt%) and strong adhesion strength (5.232 ± 0.26 MPa), while poly(DcTa-sa) and poly(DcTa-da) showed outstanding surface properties with very low surface free energy values (22.91 and 22.84 mJ m⁻²). These results highlight the utility of smart and sustainable benzoxazine chemistry and offer a facile and green synthetic approach to access hydrogen bonding-rich bio-based benzoxazine resins with many attractive properties.

This work reports the mesoscale artificial synthesis of a conjugated microporous polymer, CMP-1, using a hybrid coarse-grained methodology. Whilst using a coarse grain approach does give a lower density and surface area when compared to the all-atom equivalent, this allowed a simulation cell volume scale-up of up to 64 times, and an overall speed-up factor of 44% when compared to the all-atom equivalent.