Effect of Pore Size Distribution and Amination on Adsorption Capacities of Polymeric Adsorbents

Polymeric adsorbents with different properties were synthesized via suspension polymerization. Equilibrium and kinetics experiments were then performed to verify the adsorption capacities of the resins for molecules of various sizes. The adsorption of small molecules reached equilibrium more quickly than the adsorption of large molecules. Furthermore, the resins with small pores are easy to lower their adsorption capacities for large molecules because of the pore blockage effect. After amination, the specific surface areas of the resins decreased. The average pore diameter decreased when the resin was modified with either primary or tertiary amines, but the pore diameter increased when the resin was modified with secondary amines. The phenol adsorption capacities of the amine-modified resins were reduced because of the decreased specific area. The amine-modified resins could more efficiently adsorb reactive brilliant blue 4 owing to the presence of polar functional groups.

Attapulgite–MXene Hybrids with Ti3C2Tx Lamellae Surface Modified by Attapulgite as a Mechanical Reinforcement for Epoxy Composites

As a member of two-dimensional (2D) materials, MXene is an ideal reinforcement phase for modified polymers due to its large number of polar functional groups on the surface. However, it is still relatively difficult to modify any functional groups on the surface of MXene at present, which limits its application in enhancing some polymers. Herein, one-dimensional (1D) attapulgite (ATP) nanomaterials were introduced onto the surface of MXene to form ATP–MXene hybrids, which successfully improved the mechanical properties of the epoxy composites. ATP with appropriate content can increase the surface roughness of the MXene lamellae to obtain better interface interaction. Therefore, remarkable enhancement on the mechanical property was achieved by adding M02A025 (0.2 wt % MXene and 0.25 wt % ATP), which is the optimum composition in the hybrids for composite mechanical properties. Compared to neat epoxy, the tensile strength, flexural strength and critical stress intensity factor (KIC) of M02A025/epoxy are increased by 88%, 57%, and 195%, respectively, showing a high application prospect.

Polypropylene/Ethylene—And Polar—Monomer-Based Copolymers/Montmorillonite Nanocomposites: Morphology, Mechanical Properties, and Oxygen Permeability

This research reports the influence of polar monomer contents in ethylene vinyl acetate copolymer (EVA) and ethylene vinyl alcohol copolymer (EVOH) on the morphology, mechanical and barrier properties of polypropylene/ethylene copolymer (PP) reinforced with organically modified montmorillonite (MMT). PP/EVA and PP/EVOH (75/25 wt %) blends were reinforced with 3 wt % MMT in an internal mixer system. Samples were compression-molded into films of 300μ μm. The structural characterization was made using X-ray diffraction (XRD), scanning electron microscopy (SEM) and transmission electron microscopy (TEM), the mechanical properties were obtained by tension tests and the barrier properties by oxygen transmission rate (OTR). XRD patterns showed a combination of intercalated/exfoliated morphologies for the MMT, with higher d-001 interplanar distance increments for the blends with higher content of polar functional groups. SEM and TEM micrographs complement the results of the XRD analysis and show differences in the morphologies depending on the miscibility of the polyolefin and the polar monomer copolymer. Mechanical properties and oxygen permeability of composites exhibited a higher improvement, by the addition of MMT, for higher intermolecular interactions and most miscible polymeric system of the EVA. These results show that the higher the number of interactions, given by the VA or OH polar functional groups, the morphology and the miscibility between polyolefin and copolymer imply dispersion improvements of the nanocomposites and, in consequence, a higher improvement on the mechanical and barrier properties of the composite material.

Normal-Phase HPLC-ELSD to Compare Lipid Profiles of Different Wheat Flours

Normal-phase high-performance liquid chromatography (HPLC) is widely used in combination with evaporative light scattering detection (ELSD) for separating and detecting lipids in various food samples. ELSD responses of different lipids were evaluated to elucidate the possibilities and challenges associated with quantification by means of HPLC-ELSD. Not only the number and type of polar functional groups but also the chain length and degree of unsaturation of (free or esterified) fatty acids (FAs) had a significant effect on ELSD responses. Tripalmitin and trilinolein yielded notably different ELSD responses, even if their constituting free FAs produced identical responses. How FA structure impacts ELSD responses of free FAs is thus not predictive for those of triacylglycerols and presumably other lipids containing esterified FAs. Because ELSD responses of lipids depend on the identity of the (esterified) FA(s) which they contain, fully accurate lipid quantification with HPLC-ELSD is challenging and time-consuming. Nonetheless, HPLC-ELSD is a good and fast technique to semi-quantitatively compare the levels of different lipid classes between samples of comparable FA composition. In this way, lipid profiles of different flours from near-isogenic wheat lines could be compared.

Influence of sizes on tribological properties and tribofilm formation of lanthanum borate nanospheres in soybean oil

Vegetable oils exhibit excellent lubrication properties owing to their polar functional groups, which are liable to adsorb on the metal surfaces to form adsorption film and tribofilm. Additionally, nanoparticles play significant roles in enhancing the tribological performances of base oils by means of forming a tribofilm between friction parts. However, little work has been done on clarifying the interaction of nanoparticles and vegetable oils in the film-forming process. In this paper, two varieties of lanthanum borate nanospheres with average diameters of 50 nm (named LBN-1) and 105 nm (named LBN-2) were synthesized. The morphologies, size distribution, and chemical compositions of the nanospheres were characterized using a scanning electron microscopy, dynamic light scattering, Fourier transform infrared, and X-ray diffraction. The tribological characteristics of soybean oils with lanthanum borate nanospheres were evaluated by a four-ball tribo-tester. The tribological performances of soybean oils were obviously improved by lanthanum borate nanospheres. The focused-ion beam/transmission electron microscope analyses results revealed a uniform tribofilm containing LBN-1 was formed, contributing to excellent friction-reducing and anti-wear performances. Whereas the tribofilm of soybean oil/LBN-2 was uneven in thickness and contained more wear debris. The outcome of this work provides significant insights into the tribofilm formation for metal surfaces lubricated with vegetable oils containing different sizes of lanthanum borate nanoparticles.

Binding and activation of serotonergic G-protein coupled receptors by the multimodal antidepressant vortioxetine

G-protein coupled receptors are important pharmacological targets. Despite substantial progress, important questions still remain concerning the details of activation: how can a ligand act as an agonist in one receptor, but as an antagonist in a homologous receptor, and how can agonists activate a receptor despite lacking polar functional groups able to interact with helix 5? Studying vortioxetine, an important multimodal antidepressant drug, may elucidate both questions. Herein, we present a thorough in silico analysis of vortioxetine binding to 5-HT1A, 5-HT1B, and 5-HT7 receptors and compare to available experimental data. We are able to rationalize the differential mode of action of vortioxetine at different receptors, but also, in the case of the 5-HT1A receptor, we observe the initial steps of activation suggesting that interaction with helix 5 does not necessarily require a hydrogen bond as previously suggested. The results extend our current understanding of agonist and antagonist action at GPCRs.

Towards designing globular antimicrobial peptide mimics: role of polar functional groups in biomimetic ternary antimicrobial polymers

Using atomistic molecular dynamics simulations, we study the interaction of ternary methacrylate polymers, composed of charged cationic, hydrophobic and neutral polar groups, with model bacterial membrane. Our simulation data shows...

Preparation and dye adsorption properties of an oxygen-rich porous organic polymer

An oxygen-rich porous polymer containing polar carbonyl and hydroxyl groups, POP-O, was prepared, and the combination of abundant polar functional groups and high porosity endows POP-O with decent dye adsorption performance.

Surface Modification of Polyamides by Gaseous Plasma—Review and Scientific Challenges

A review of the most significant scientific achievements in the field of surface modification of polyamides by non-equilibrium plasma treatments is presented. Most authors employed atmospheric pressure discharges and reported improved wettability. The super-hydrophilic surface finish was only achieved using a low-pressure plasma reactor and prolonged treatment time, enabling both the nanostructuring and functionalization with polar functional groups. The average increase of the oxygen concentration as probed by XPS was about 10 at%, while the changes in nitrogen concentrations were marginal in almost all cases. The final static water contact angle decreased with the increasing treatment time, and the oxygen concentration decreased with the increasing discharge power. The need for plasma characterization for the interpretation of experimental results is stressed.