A Versatile Synthetic Approach toward Hyper-Cross-Linked Styrene-Based Polymers and Nanocomposites

Green preparation of magnetic pyrene-based hyper-cross-linked polymer using dual-purpose ferric chloride reagent for extraction of polycyclic aromatic hydrocarbons from natural water bodies

A magnetic hyper-cross-linked polymer Fe3O4/HCPPYR was prepared using pyrene as the monomer and formaldehyde dimethyl acetal (FDA) as the cross-linking agent. The objective of green chemistry was achieved by employing FeCl3 during the synthesis, as it played a dual role of a catalyst for the Friedel-Crafts reaction and an iron source for the synthesis of magnetic Fe3O4, thus maximizing efficiency and minimizing waste. Fe3O4/HCPPYR was applied as a sorbent for magnetic solid-phase extraction (MSPE) to extract fifteen polycyclic aromatic hydrocarbons (PAHs) from water. The effects of different parameters such as the quantity of adsorbent, the extraction time, the desorption conditions, the pH value and the effect of the salt concentration on the extraction efficiency were optimized. A simple and efficient method in combination with gas chromatography-mass spectrometry (GC-MS) (Fe3O4/HCPPYR-MSPE/GC-MS) was developed and successfully applied for the detection of PAHs in environmental water samples The analytical method showed LODs in the range of 0.004-0.06 µg L-1, which proved to be adequate for the detection all 15 PAHs at trace concentration. Spiked recoveries of PAHs in actual water samples ranged from 85.2 % to 118.5 % with relative standard deviations (RSDs) below 10.2%. These results indicate that the method has a good potential for reusability and possesses excellent sensitivity. This study showcased the potential of Fe3O4/HCPPYR composites in effectively removing organic pollutants from the aqueous environments, demonstrating their ability for water treatment applications.

Adsorption-Enhanced Glucan Oligomer Production from Cellulose Hydrolysis over Hyper-Cross-Linked Polymer in Molten Salt Hydrate

Selective saccharification of cellulose into glucose is a critical step for utilization of lignocellulosic biomass. Molten salt hydrates (MSHs) have shown promising performance in selectively converting cellulose into glucose because of the high solubility of cellulose in the solvent. However, the separation of formed glucose from the MSHs is still a grand challenge. To address this issue, we developed a two-step process, where crystalline cellulose is hydrolyzed into short-chain glucan oligomers in MSHs followed by separation and subsequent hydrolysis of the formed oligomers into glucose under mild conditions. The two-step method provides an easy separation for glucan oligomers from the MSHs without sacrificing the selectivity to glucose. Application of the method for crystalline cellulose is, however, limited to a relatively low concentration, 26.2 mg/mL, because of the formation of byproducts in the MSH that facilitate oligomers degradation. In this work, reactive adsorption was employed to in situ remove the byproducts formed during cellulose hydrolysis in the MSH. It was found that hyper-cross-linked polymer (HCP) made from the polymerization of 4-vinylbenzyl chloride and divinylbenzene can selectively adsorb 5-hydroxymethylfurfural (5-HMF) and levulinic acid (LA) while showing negligible sugar adsorption in both water and the MSH. With the reactive adsorption approach, byproducts including 5-HMF and LA were removed from the reaction media under reaction conditions, and their negative effects on oligomer degradation were inhibited. In the presence of the HCP, the obtained glucan oligomer concentration was enhanced from less than 54.2 to 247.1 mg mL-1 when the weight ratio of cellulose was increased to MSH from 1:60 to 1:4, exhibiting an oligomer yield of 69.5%. The HCP can be effectively separated from the reaction media by filtration and regenerated by oxidation with hydrogen peroxide. Application of reactive adsorption with HCP for cellulose hydrolysis in the MSH provides a promising method to produce glucan oligomers and glucose with an improved yield and efficiency.

Valorization and Mechanical Recycling of Heterogeneous Post-Consumer Polymer Waste through a Mechano-Chemical Process

In this paper, a sustainable strategy to valorize and recycle heterogeneous polymer-based post-consumer waste is proposed. This strategy is based on a high-energy mechano-chemical treatment and has been applied to a polyolefin-rich fraction, coded as FIL/S, deriving from household plastic waste collection. This processing, performed in a planetary ball mill, allowed us to obtain fine grinding and, consequently, to induce an intimate mixing of the different polymer fractions and contaminants composing the FIL/S, as demonstrated by SEM analysis. As a result, an improvement in the deformability of the treated material was obtained, recording values for elongation at the break which were two and half times higher than the neat FIL/S. Finally, the addition of small amounts of organic peroxide during mechano-chemical treatment was tested, determining a more homogeneous morphology and a further improvement in mechanical parameters.

Irreversible deformation of hyper-crosslinked polymers after hydrogen adsorption

Hyper-crosslinked polymers (HCPs) have been produced by the Friedel-Crafts reaction using anthracene, benzene, carbazole or dibenzothiophene as precursors and dimethoxymethane as crosslinker, and the effect of graphene oxide (GO) addition has been studied. The resulting HCPs were highly microporous with BET areas (A_BET) between 590 and 1120 m²g^-1. The benzene-derived HCP (B1FeM2) and the corresponding composite with GO (B1FM2-GO) exhibited the highest A_BET and were selected to study their hydrogen adsorption capacities in the pressure range of 0.1 - 14 MPa at 77 K. The maximum H₂ excess uptake was 2.1 and 2.0 wt% for B1FeM2 and B1FeM2-GO, respectively, at 4 MPa and 77 K. The addition of GO reduced the specific surface area but increased the density of the resultant HCP-GO composites, which is beneficial for practical applications and proves that materials giving higher gravimetric storage capacities are not necessarily those that offer higher volumetric capacities. H₂ adsorption-desorption cycles up to 14 MPa showed irreversible deformation of both HCP and HCP-GO materials, which calls into question their application for hydrogen adsorption at pressures above 4 MPa.

Mesoporous silica nanoparticles as carriers of active agents for smart anticorrosive organic coatings: a critical review

Mesoporous silica nanoparticles (MSN) have attracted increasing interest for their applicability as smart nanocarriers of corrosion inhibitors, due to their porous structure, resistance to main corrosive environments and good compatibility with polymer coatings. In this review, the main synthetic routes to obtain MSN with tailored textural properties, the design of different loading and stimuli-induced release strategies, the development of advanced organic nanocomposite coatings with MSN and the validation of their anticorrosive performances are reviewed and compared. Through a critical analysis of the literature, the most promising research trends and perspectives to exploit the highly interesting properties of MSN in advanced organic coatings are proposed.

Sulfur-Decorated Hyper-Cross-Linked Coal Tar: A Microporous Organic Polymer for Efficient and Expeditious Mercury Removal

Hyper-cross-linked microporous organic polymers are a class of porous materials that have captured widespread attention owing to their high surface areas and wide range of monomeric sources. Balancing economy with performance is the initial hurdle when designing effective hyper-cross-linked microporous organic polymers. Herein, we demonstrated an inexpensive sulfurated solvent-knitted hyper-cross-linked microporous polymer scaffold, named sulfur-decorated hyper-cross-linked coal tar (CTHP-SES), utilizing coal tar as an aromatic monomer with numerous positions for potential chelation of toxic metals, particularly mercury, from water. The resulting material illustrated selective adsorption of mercury from both water (1037 mg g^-1) and the gas phase (416 mg g^-1) with rapid kinetics (183.67 mg min^-1 g^-1), good recyclability (4 runs), and excellent stability under both strong basic and acidic conditions. CTHP-SES was able to reduce the concentration of the Hg(II) solution from 1 mg L^-1 to 32 μg L^-1 after 10 min due in part to the promising distribution coefficient (K_d = 2.371 × 10⁶ mL g^-1). These results show that CTHP-SES offers a promising and practical platform to cope with a variety of environmental contaminations.

Hyper-Crosslinked Polymer Nanocomposites Containing Mesoporous Silica Nanoparticles with Enhanced Adsorption Towards Polar Dyes

The development of new styrene-based hyper-crosslinked nanocomposites (HCLN) containing mesoporous silica nanoparticles (MSN) is reported here as a new strategy to obtain functional high surface area materials with an enhanced hydrophilic character. The HCLN composition, morphology and porous structure were analyzed using a multi-technique approach. The HCLN displayed a high surface area (above 1600 m2/g) and higher microporosity than the corresponding hyper-crosslinked neat resin. The enhanced adsorption properties of the HCLN towards polar organic dyes was demonstrated through the adsorption of a reactive dye, Remazol Brilliant Blue R (RB). In particular, the HCLN containing 5phr MSN showed the highest adsorption capacity of RB.

A New Route for Low Pressure and Temperature CWAO: A PtRu/MoS2_Hyper-Crosslinked Nanocomposite

PtRu/MoS₂ nanoparticles (NPs) (PtRu alloy partially coated by one-layer MoS₂ nanosheets) were prepared through a ‘wet chemistry’ approach. The obtained NPs were directly embedded, at 5 parts per hundred resin/rubber (phr) loading, in a poly (divinylbenzene-co-vinyl benzyl chloride) hyper-crosslinked (HCL) resin, synthesized via bulk polymerization of the resin precursors, followed by conventional FeCl₃ post-crosslinking. The obtained HCL nanocomposites were characterized to evaluate the effect of the NPs. It shows a high degree of crosslinking, a good dispersion of NPs and a surface area up to 1870 ± 20 m²/g. The catalytic activity of the HCL nanocomposite on phenol wet air oxidation was tested at low air pressure (P_air = 0.3 MPa) and temperature (T = 95 °C), and at different phenol concentrations. At the lower phenol concentration, the nanocomposite gives a total organic carbon (TOC) conversion of 97.1%, with a mineralization degree of 96.8%. At higher phenol concentrations, a phenol removal of 99.9%, after 420 min, was achieved, indicating a quasi-complete depletion of phenol, with a TOC conversion of 86.5%, corresponding to a mineralization degree of 84.2%. Catalyst fouling was evaluated, showing good reusability of the obtained nanocomposite.

Synthesis of MWCNT-Based Hyper-Cross-Linked Polymers with Thickness-Tunable Organic Porous Layers

Using a simple, versatile, and flexible, low-cost, and high-efficient solvent knitting method, we report the synthesis of one-dimensional (1D) multiwalled carbon nanotube (MWCNT) based hyper-cross-linked polymers (HCPs). The composite materials combine the special 1D linear morphology and excellent mechanical properties of MWCNTs with high specific surface area and abundant pore structure characteristics of HCPs. Compared with pristine MWCNTs, the MWCNT-based HCPs exhibit higher surface area and significant enhancement in gas (such as CO₂ and H₂) uptake capacities that shows their potential applications in gas adsorption and storage. Moreover, the thickness of porous HCP layers, which wrap around MWCNTs can be tuned by controlling the amount of monomer used, and the Brunauer-Emmett-Teller (BET) surface area and gas adsorption capacities are also adjustable. These findings show the potential applications of 1D carbon nanotube-based HCP composite materials in gas uptake and storage.

A novel synthetic method for tubular nanofibers

A one-pot method with a new dual oil phase system has been developed for the fabrication of tubular polymer nanofibers.

Microporous Hyper-Crosslinked Polystyrenes and Nanocomposites with High Adsorption Properties: A Review

Hyper-crosslinked (HCL) polystyrenes show outstanding properties, such as high specific surface area and adsorption capability. Several researches have been recently focused on tailoring their performance for specific applications, such as gas adsorption and separation, energy storage, air and water purification processes, and catalysis. In this review, main strategies for the realization of HCL polystyrene-based materials with advanced properties are reported, including a summary of the synthetic routes that are adopted for their realization and the chemical modification approaches that are used to impart them specific functionalities. Moreover, the most up to date results on the synthesis of HCL polystyrene-based nanocomposites that are realized by embedding these high surface area polymers with metal, metal oxide, and carbon-based nanofillers are discussed in detail, underlining the high potential applicability of these systems in different fields.

Chitosan hydrogels embedding hyper-crosslinked polymer particles as reusable broad-spectrum adsorbents for dye removal

The removal of dye and toxic ionic pollutants from water is an extremely important issue that requires systematic and efficient adsorbent preparation strategies. To address this challenge, we developed composite chitosan (CS)-based hydrogels containing hyper-crosslinked polymer (HCP) particles to be used as broad-spectrum adsorbents. The goal is to efficiently combine the dye adsorption ability of chitosan and the capacity of the porous particles of trapping pollutant molecules. The HCP particles are well distributed and firmly embedded into the chitosan matrix and the composite hydrogels exhibit improved mechanical properties. Adsorption experiments reveal a synergistic effect between CS and HCP particles, and the samples are able to remove both anionic and cationic dyes (indigo carmine, rhodamine 6G and sunset yellow) from water. The maximum dye uptake is higher than that of comparable biosorbents. Moreover, the mechanical properties of the composite hydrogels are enhanced respect to pure CS, and the samples can be regenerated and reused keeping their adsorption ability unaltered over successive cycles of adsorption, desorption, and washing.