Cross-linked Divinylbenzene Research Articles

Accelerating Development of Submicron-Thick Initiated Chemical Vapor Deposition (iCVD)-Derived Polymer Electrolytes for All Solid-State Batteries Via Pre-Screening Bulk Surrogates

Initiated chemical vapor deposition (iCVD) is an emerging method for generating submicron-thick, conformal polymer coatings on structurally complex substrates, including those of interest to all solid-state 3D batteries, fuel cells, and capacitive deionization devices. From the perspective of the energy-storage community, the utility of iCVD arises from the ability to create conformal polymer anion- or cation-conducting solid-state electrolytes, artificial solid-electrolyte interphase (SEI) layers, and surface property-modifying coatings. Expanding the library of polymer chemistries and structures beyond those obtained using standard vinyl-containing iCVD monomers is essential to address the challenges facing next-generation, advanced energy storage (e.g., cycle life, suppression of unwanted ion transport). However, opening up this synthetic property-performance space for iCVD-generated materials challenges the throughput of iCVD and greatly increases the number of characterization experiments. To circumvent this challenge, we previously reported that bulk poly(dimethylaminomethylstyrene), pDMAMS, synthesized using bulk solution polymerization serves as a surrogate for iCVD-derived pDMAMS.1,2 We now extend the viability of bulk polymer surrogates to other polymer chemistries as a pre-screening option to accelerate the design and evaluation of iCVD-derived solid-state polymer electrolytes. For a selected test case involving single-anion conducting alkaline polymer electrolytes, we demonstrate how trends observed in polymer design regarding ion/mass transport and morphology on traditional bulk-synthesized polymers translate to iCVD-prepared analogs of the same systems. For example, we show that for a co-polymer system comprising divinylbenzene (DVB) and quaternized dimethylaminomethylstyrene (p[DVB-DMAMS+], increasing the crosslinking DVB content decreases ionic conductivity and restricts dynamic freedom. Using this understanding, we formulate an appropriate pre-optimized iCVD-derived p[DVB-DMAMS+] electrolyte and verify that its performance trend aligns with that of the bulk copolymer.1. Ford, Hunter O., et al. Non-line-of-sight synthesis and characterization of a conformal submicron-thick cationic polymer deposited on 2D and 3D substrates. RSC Applied Interfaces (2024); doi: 1039/d3lf00256j.2. Ford, Hunter O., et al. Submicron-thick single anion-conducting polymer electrolytes. RSC Applied Interfaces (2024); doi: 10.1039/d3lf00257h.

Polymerization of Sodium 4-Styrenesulfonate Inside Filter Paper via Dielectric Barrier Discharge Plasma

This work explores the polymerization of sodium 4-styrenesulfonate (NaSS) inside filter paper using dielectric barrier discharge (DBD) plasma and its application in the environmental field. The plasma-based technique, performed under mild conditions, solves common problems associated with conventional polymerization inside porous materials. The polymerization process was monitored using Fourier-transform infrared (FTIR) spectroscopy, which confirmed the consumption of double bonds, particularly in NaSS samples containing the optimal concentration of crosslinker divinyl benzene (DVB) (0.25% wt). Our work demonstrates the effectiveness and promise of DBD plasma as a substitute polymerization approach, especially for those in porous materials.

Synthesis and Evaluation of High-Temperature Resistant Polymer Plugging Agent for Water-Based Drilling Fluids.

As the exploration and development of deep wells have emerged as a key option to extract more oil and gas resources trapped underneath, high-temperature formations impose stringent requirements on the thermal stability of plugging agents used in water-based drilling fluids. In this work, β-cyclodextrin, with its unique conical toroidal rigid stable structure and internal hydrophobic and external hydrophilic special adsorption capacity, was first grafted with maleic anhydride to prepare a silicone polymer and then copolymerized with dimethyldiallylammonium chloride (DMDAAC) in the presence of coupling agent vinyltriethoxysilane (A151) and cross-linking divinylbenzene (DVD) to finally obtain a high-temperature resistant plugging agent (AMMD). Subsequently, the molecular structure was evidenced and the performance of AMMD was examined in the polysulfonate-base fluid via a series of tests including high-temperature high-pressure filtration loss, sand tray plugging, and drilling fluid displacement, and the results were compared with the counterpart Soltex under the same conditions. The optimal synthesis conditions for the plugging agent were found as total monomer concentration of 25%, initiator mass fraction of 1% (based on the mass of monomers), monomer feed ratio of m (DVD):m(A151):m(DMDAAC):m(MD) of 15:3:2:15, pH value of 10, reaction temperature of 75 °C, and reaction time of 4 h. FT-IR spectra indicated that the monomers used to prepare AMMD were successfully involved in the reaction for the design of the plugging agent structure. TGA showed that AMMD has a total weight loss of about 35.98% in the range of 284 to 453 °C. Moreover, the addition of 3%AMMD into the base fluid produced a 4.38-fold and 3.8-fold filtration loss control over 60 min at 200 °C using 400 and 800 mD sand trays, respectively, which were comparatively higher than the commercially available Soltex (ca. 3.72-fold and 3.14-fold, respectively, using 400 and 800 mD). This then contributed to AMMD's superior plugging performance in drilling fluid based on the drilling fluid displacement experiment, implying that AMMD could find potential use as a plugging agent in polysulfonate drilling fluid under severe geothermal conditions.

Design of chiral acidic molecularly imprinted polymer for the enantioselective separation of (±)‐DOPA

AbstractBackgroundThe study focuses on developing a stable enantioselective matrix for the efficient chiral identification and enantioresolution of l‐DOPA and (±)‐DOPA. The matrix is derived from a copolymeric material made from poly[(vinylsulfonic acid)‐co‐(4‐vinylpyridine)] crosslinked with divinylbenzene.Resultsl‐DOPA‐vinylsulfonamide was synthesized and characterized. This chiral sulfonamide was copolymerized with 4‐vinylpyridine in the presence of a divinylbenzene crosslinker, using azobisisobutyronitrile as a thermal initiator. Post‐polymerization, the polymeric particles were treated with NaOH and subsequently washed with acid to remove the integrated l‐DOPA species. Scanning electron microscopy and Fourier transform infrared spectroscopy confirmed the imprinted l‐DOPA‐IP particles. The manufactured l‐DOPA‐IP demonstrated a tenfold greater affinity for l‐DOPA compared to d‐DOPA. Langmuir adsorption experiments at pH 6 showed a maximum capacity of 162 mg g−1. Enantiomeric excess values for l‐ and d‐DOPA, determined through optical separation using a column approach, were 94% and 82%, respectively, in the loading and recovery solutions.ConclusionThe developed copolymeric material effectively served as an enantioselective matrix, exhibiting high selectivity and capacity for l‐DOPA. The process demonstrated efficient chiral identification and separation, achieving significant enantiomeric excess values for both l‐ and d‐DOPA. © 2024 Society of Chemical Industry (SCI).

Synthesis of iron oxide nanoparticles encapsulated poly(styrene‐co‐4‐vinyl pyridine) nanocomposites for column adsorption and photocatalytic degradation of para nitrophenol from water

AbstractStyrene (St), 1,4 vinyl pyridine (4VP) monomers and divinyl benzene (DVB) monomer‐cum‐crosslinker at different molar ratios were subjected to emulsion polymerization in the presence of FeCl2, 6H2O/FeCl3⋅4H2O followed by the treatment with an aqueous ammonia solution to produce several iron oxide nanoparticles (IONs) impregnated crosslinked copolymer composites. The resulting polymer metal nanocomposites (PMNCs) were characterized by FTIR, proton and 13C NMR, UV–visible spectroscopy, XRD, XPS, DLS, magnetic properties, SEM and TEM. The PMNCs were used for batch and column adsorption and photocatalytic degradation of p‐nitrophenol (PNP) from water. The PMNC4 composite prepared with an styrene:4VP molar ratio of 5:1 (16.7 mol% 4VP), 4 wt.% DVB crosslinker and 0.025/0.05 molar ratios of Fe(II)/Fe(III) salts leads to an optimum batch equilibrium adsorption (qe, mg/g)/removal% of 496.36/99.3 PNP from aqueous PNP of concentration 100 mg/L. The same composite showed an equilibrium PNP adsorption (qe) of 114.2 mg/g polymer and a removal% of 26.8 for an inlet feed concentration (Ci, mg/L)/flow rate (Qt, mL/min)/bed height (h, mm) of 100/30/30 in a fixed bed. The PMNC4 polymer showed a photodegradation efficiency of 98% with a 1st order rate constant of 0.029 min−1 after 70 min of degradation of 100 mg/L PNP in solar light.Highlights Copolymer network of styrene, 4 vinyl pyridine and DVB were synthesized. Iron oxide nanoparticles were introduced into the network in‐situ during synthesis. The metal polymer nanocomposites (PMNCs) were characterized. Synthesis parameters were optimized with respect to batch adsorption of PNP. PMNCs showed excellent fixed bed adsorption and photocatalytic degradation of PNP.

Development of biomimetic hexapeptide functionalized monolithic material for capillary microextraction of microcystins in environmental waters

In this work, a histidine-tagged hexapeptide functionalized monolithic material is described for the efficient capillary microextraction (CME) of microcystins (MCs) from environment waters. 1-Vinylimidazole (VIM) monomer was utilized to synthesize the matrix polymer monolith by the copolymerization with divinylbenzene (DVB) crosslinker in the presence of radical initiator azobisisobutyronitrile (AIBN). The affinity sorbent was then prepared by a metal ion chelation-based multi-step approach, in which the histidine tag peptide Trp-His-Trp-Leu-Gln-Trp (WHWLQW) was functionalized on a Cu2+ modified polymer monolith via a chelation reaction between the imidazole group of histidine and Cu2+. The resultant WHWLQW functionalized monolithic material had high affinity, hierarchical porosity and good mechanical stability. Especially, it exhibited favorable enrichment capacity for MCs compared to other affinity materials as previously reported. With the optimized CME protocol, MCs at ultra-trace level can be analyzed by CME coupled to high performance liquid chromatography-mass spectrometry (HPLC-MS) in different aqueous environmental matrices. The average recoveries were ranged from 89.3% to 104.5% with relative standard deviations (RSD%) of 2.1–8.4, demonstrating high extraction efficiency and repeatability. The limits of detection (LODs) of MCs were determined to be 0.28–0.45 ng L-1. This novel biomimetic sorbent shows promising potential for the enrichment of ultra-trace pollutants in environment waters.

Hierarchical Emulsion-Templated Monoliths (polyHIPEs) as Scaffolds for Covalent Immobilization of P. acidilactici.

The immobilized cell fermentation technique (IMCF) has gained immense popularity in recent years due to its capacity to enhance metabolic efficiency, cell stability, and product separation during fermentation. Porous carriers used as cell immobilization facilitate mass transfer and isolate the cells from an adverse external environment, thus accelerating cell growth and metabolism. However, creating a cell-immobilized porous carrier that guarantees both mechanical strength and cell stability remains challenging. Herein, templated by water-in-oil (w/o) high internal phase emulsions (HIPE), we established a tunable open-cell polymeric P(St-co-GMA) monolith as a scaffold for the efficient immobilization of Pediococcus acidilactici (P. acidilactici). The porous framework's mechanical property was substantially improved by incorporating the styrene monomer and cross-linker divinylbenzene (DVB) in the HIPE's external phase, while the epoxy groups on glycidyl methacrylate (GMA) supply anchoring sites for P. acidilactici, securing the immobilization to the inner wall surface of the void. For the fermentation of immobilized P. acidilactici, the polyHIPEs permit efficient mass transfer, which increases along with increased interconnectivity of the monolith, resulting in higher L-lactic acid yield compared to that of suspended cells with an increase of 17%. The relative L-lactic acid production is constantly maintained above 92.9% of their initial relative production after 10 cycles, exhibiting both its great cycling stability and the durability of the material structure. Furthermore, the procedure during recycle batch also simplifies downstream separation operations.

Bi-functional phosphonium poly(ionic liquid)s catalyzed CO2-promoted hydration of ethylene oxide

The highly selective production of monoethylene glycol (MEG) from ethylene oxide (EO) is desirable at low H2O/EO molar ratio, however, the development of an efficient heterogeneous catalyst for the reaction is a challenge. Herein, a series of bi-functional poly(ionic liquid)s (BF-PILs) were successfully synthesized by radical copolymerization of polymerizable phosphonium/ammonium ionic liquids, N-vinyl imidazole and cross-linker divinylbenzene (DVB). The structure and thermal stability of BF-PILs were characterized by NMR, FT-IR, elemental analysis and TGA. These BF-PILs could be swollen in the H2O and MEG mixture and the swelling ratio (Q) increased with the increase of the MEG mole fraction. Under swelling in the H2O and MEG mixture (1:1), BF-PILs presented an irregular channel structure with the diameter of 1–20 μm observed by the cryo-scanning electron microscope (cryo-SEM). BF-PILs were applied to catalyze the CO2-promoted hydration of EO at a low H2O/EO ratio of 1.5:1. The catalytic activities of phosphonium BF-PILs were superior to ammonium BF-PILs, and poly[(Ph)3VBPBr-VIm] with the greatest Q in the H2O and MEG mixture (1:1) gave highest yield (96.1%) and selectivity (97.3%) of MEG. The CO2-promoted hydration of EO involved the cycloaddition of EO with CO2 to produce ethylene carbonate (EC), and followed by the hydrolysis of EC to produce MEG. Kinetic experiments confirmed that phosphonium ionic liquid species mainly catalyzed CO2 cycloaddition and imidazole catalyzed hydrolysis of EC. Furthermore, poly[(Ph)3VBPBr-VIm] exhibited good generality and could be reused up to eight times without significant decrease of its initial activity.

(Invited) Radiation-Grafted Anion-Exchange Membranes for Reverse Electrodialysis (RED): The Effect of Changing Functional Groups on Key Properties

Radiation-grafted anion-exchange membranes (RG-AEM) are being developed at the University of Surrey in order to study a variety of chemistries and morphologies for use in a range of electrochemical applications. It is now clear that the ideal base films and grafted functional chemistries, required to fabricate the RG-AEMs, are different for each technology.Over the last decade or so, RG-AEMs with more than 100 different chemical configurations have been fabricated. Most of these have not been studied in detail as the focus was traditionally on RG-AEMs for use in alkaline membrane fuel cells where AEMs needed to have good stabilities in alkali. This has meant the focus was only on a small number of these chemistries. However, other electrochemical applications, such as electrodialysis (ED) and reverse electrodialysis (RED, a salinity gradient power technology) require AEMs to be operating in more neutral pH environments. This allows a wider range of chemistries to be used. For such applications, properties such as permselectivity and fouling resistance can be as important as ion conductivity.This presentation will provide a summary of recent RG-AEM developments at Surrey. A focus will be on the study of AEM chemistries for potential use in RED, with a study on the effects of crosslinking, head-group chemistry, and ion-exchange capacity. It has been found that despite being highly ionically conductive, non-crosslinked RG-AEMs have intrinsically low permselectivities and are prone to excessive levels of swelling in water (especially at high ion-exchange capacities). The incorporation of crosslinking can improve permselectivities, and lower swelling, but this often leads to detrimental drops in ion conductivity. Interestingly, the choice of head-group chemistry can have an effect on properties such as permselectivity.This research has been funded by EPSRC grants EP/M014371/1, EP/M022749/1, EP/R044163/1, and EP/T009233/1 along with EU Project SELECTCO2 (grant agreement 851441). Select recent references: R. Bance-Soualhi, M. Choolaei, S. A. Franklin, T. R. Willson, J. Lee, D. K. Whelligan, C. Crean, J. R. Varcoe, "Radiation-grafted anion-exchange membranes for reverse electrodialysis: a comparison of N,N,N',N'-tetramethylhexane-1,6-diamine crosslinking (amination stage) and divinylbenzene crosslinking (grafting stage)", J. Mater. Chem. A, 9, 22025 (2021) [CC-BY].K. M. Meek, C. M> Reed, B. Pivovar, K.-D. Kreuer, J. R. Varcoe, R. Bance-Soualhi, "The alkali degradation of LDPE-based radiation-grafted anion-exchange membranes studied using different ex situ methods", RSC Adv., 10, 36467 (2020) [CC-BY].T. R. Willson, I. Hamerton, J. R. Varcoe, R. Bance-Soualhi, "Radiation-grafted cation-exchange membranes: an initial ex situ feasibility study into their potential use in reverse electrodialysis", Sustainable Energy Fuels, 3, 1682 (2019) [CC-BY]L. Wang, X. Peng, W. E. Mustain, J. R. Varcoe, "Radiation-grafted anion-exchange membranes: the switch from low- to high-density polyethylene leads to remarkably enhanced fuel cell performance", Energy Environ. Sci., 12, 1575 (2019) [CC-BY].

Controlled block-polymerization of styrene, divinylbenzene and ethylene oxide. Intermolecular cross-linking towards well-defined miktoarm copolymer stars

• Synthesis of well-defined miktoarm copolymer stars. • Control over the molecular weight and composition for both arm species. • Controlled polymerization of poly(divinylbenzene). • Intermolecular cross-linking of linear triblock terpolymers. A novel approach for the synthesis of miktoarm copolymer stars with divinylbenzene cross-linked core, via anionic polymerization is reported. This synthetic route gives access to polymers, characterized by low dispersity values and improved structural homogeneity for both arm species. Specifically, miktoarm copolymer stars of A n B n type, with cross-linked divinylbenzene (DVB) core and arms of polystyrene (PS) and poly(ethylene oxide) (PEO), are synthesized via anionic polymerization and sequential monomer addition, employing high vacuum techniques. Analytically, the first step involves the synthesis of a triblock terpolymer PS- b -PDVB- b -PEO. Then, in the presence of a free radical initiator the pending vinyl groups of the middle DVB block cross-link intermolecularly, leading to the final miktoarm copolymer star. The novelty of the proposed synthetic route, lies in the potassium alkoxide co -initiator, which is responsible for the controlled polymerization of both DVB and EO in one pot, without the need for end group modification between the two steps. Concerning the final polymer, there are numerous benefits advancing from this synthetic protocol, such as the control of the molecular characteristics of both arms, as well as the easily confirmed structural integrity of the precursor triblock which is inherited to the resulting miktoarm star. For comparison reasons, another batch of (PS)(PEO) miktoarm copolymers was synthesized, following the “in-out” synthetic route. For this reason, styrene was polymerized using s -BuLi, which is used as macroinitiator for the polymerization/cross-linking of DVB, resulting PS star with DVB cross-linked core. With the addition of EO, in the presence of p4 t -Bu phosphazene base, PEO arms are polymerized, initiating from the core’s active cites outwards.

Addition of divinyl benzene comonomer to glycidyl methacrylate grafting to cyclic natural rubber

The process of thermally grafting glycidyl methacrylate (GMA) on cyclic natural rubber (CNR) compared to the addition of an initiator of organic peroxide, dicumyl peroxide (DCP) and using cross-linker divinyl benzene (DVB) has been carried out by means of melt processing. The main aims of the modified GMA grafted to CNR was to increase the polarity of the polymer to be used as a compatibiliser agent in asphalt modification. The addition of DVB comonomer in the processing was to increase the amount of GMA implanted in cyclic rubber as measured by the degree of GMA grafting. The grafting method was carried out by melting polymer (melt processing) at high temperatures in the reactor internal mixer (Brabender model). The grafting reaction took place at a temperature of 160°C, 60 rpm rotor rotation for 10 minutes of mixing. To determine the GMA grafting reaction on cyclic rubber, characterization was carried out with Fourier Transformed Infra Red (FT-IR) while the degree of GMA grafting on natural rubber was determined by acid-base titration method in organic solvents. It was found that the GMA grafting process on cyclic natural rubber could easily occur in the melting phase at high temperatures and increase with the addition of dicumyl peroxide (DCP) peroxide. Although the addition of divinyl benzene (DVB) comonomer can increase the degree of grafting of GMA on CNR, the addition of comonomer can cause high cross-linking.

Sulfonated polyvinylidene fluoride-crosslinked-aniline-2-sulfonic acid as ion exchange membrane in single-chambered microbial fuel cell

A novel interpenetrating polymeric network (IPN) of sulfonated polyvinylidene fluoride (SPVDF), nano-alumina (Al2O3), and aniline-2-sulfonic (A2S) acid with crosslinker divinylbenzene (DVB) is employed as an ion-exchange membrane in single-chambered microbial fuel cells (MFCs). Results reveal that the increasing concentration of A2S (10, 20, and 30 wt%) enhances the relative hydrophilicity and other intrinsic properties of the membranes. A series of characterizations like water uptake, swelling ratio, ion-exchange, proton conductivity, and tensile testing, affirms the enhanced attributes of the casted membranes. The increasing concentration of crosslinker DVB (> 1.4 wt%) constricts the internal spacing of the membrane that, in turn, hinders the transverse ionic conduction within the highly crosslinked, AS30 membrane. A maximum power and current density of 450.36 ± 23mW m-2 and 1734 ± 87mA m-2 was found in AS20 fitted MFC with around 89% of chemical oxygen demand (COD) removal in 30 days of operation. Incorporation of A2S and Al2O3 in SPVDF moiety demonstrates an approximate increment of 36% and 7% higher MFC performance over n-SPVDF and highly crosslinked AS30 membrane. The relative effect of these novel IPN membranes has been highlighted here as cost-efficient separator in MFCs for green electricity production, employing mixed firmicutes as biocatalyst.

Synthesis of anisotropic colloids with concave and convex structures.

Anisotropic colloidal particles with concave and convex structures are useful in both theoretical studies and applications. In this work, we mass-produced polystyrene (PS) colloidal particles with multiple concavities through dispersion polymerization techniques. By increasing the delayed feeding time td of the cross-linker divinylbenzene (DVB), the morphological evolution of particles can be classified into two stages, during which the formation of different concavities is consistent with either the buckling mechanism or phase separation mechanism. By varying the DVB dosage, we found that the size of the big chamber formed on the particle surfaces decreases as the DVB dosage increases. Then, using these concave particles as seeds, 2-5 μm anisotropic colloids with various shapes, including spherical, ellipsoidal, snowman and multi-protrusion, were synthesized by seeded emulsion polymerization. Moreover, our results show that both the chambers and long narrow ditches on the surface of seeds can be the active sites for monomers to gather and polymerize, but monomers in the big chamber have a priority to polymerize first when big and small concavities both exist on seeds. The results of this study could mean great potential in synthesizing a variety of anisotropic particles with well-controlled concave morphologies.

Photocatalytic elimination of interfacial water pollutants by floatable photoreactive composite nanoparticles

Disastrous oil spills cause severe environmental issues. The shortcomings of current cleaning methods for remediating oil have prompted the latest research drive to create intelligent nanoparticles that absorb oil. We, therefore, synthesized 197 ± 50 nm floatable photoreactive hybrid nanoparticles with Ag–TiO2 plasmonic photocatalyst (Eg = 3.08 eV) content to eliminate interfacial water pollutants, especially toluene-based artificial oil spill. We found that the composite particles have non-wetting properties in the aqueous media and float easily on the surface of the water due to the moderate hydrophobic nature (Θ = 113°) of the matrix of polystyrene, and these properties lead to elevated absorption of the interfacial organic pollutants (e.g., mineral oil). We showed that (28.5 mol%) divinylbenzene cross-linker content was required for adequate swelling capacity (2.15 g/g), whereas incorporated 15.8% Ag–TiO2 content in the swollen particles was enough for efficient photodegradation of the artificial oil spill under 150 min LED light (λmax = 405 nm) irradiation. The swollen polymer particles with embedded 32 ± 7 nm Ag–TiO2 content increase the efficiency of photooxidation by increased the direct contact between both the photocatalysts and the artificial oil spill. Finally, it was also presented that the composite particles destroy themselves: after approximately one and a half months of continuous LED light irradiation, the organic polymer component of the composite was almost completely (88.5%) photodegraded by the incorporated inorganic photocatalyst particles.

Synthesis and characterisation of porous polyvinylpyrrolidone-co-poly(divinylbenzene) (PVP-co-PDVB) copolymer resins for the isolation of betalains from red beetroot

Betalain is a natural pigment with serious antioxidant and biological activities currently used as a food colourant, however; the isolation of this compound is difficult because of its instability. The research was aimed to synthesise and characterise the copolymeric adsorbents for the recovery of betalains by means of the solid-phase extraction (SPE) technique. For this purpose, divinylbenzene (crosslinker) was polymerised with polyvinylpyrrolidone containing vinyl groups by using free radical polymerisation, and toluene was used as a porogene. Polymeric resins in different polyvinylpyrrolidone/divinylbenzene (PVP/DVB) and toluene/divinylbenzene (Tol/DVB) rates were synthesised. The effects of these parameters on the polymerisation efficiency, size distribution, morphology, swelling properties and adsorption capacities of adsorbents were investigated in the later characterization stage. Adsorption tests were conducted by analyzing phenol adsorption in batch model systems. The KOD-4 coded adsorbent exhibited the best performance in adsorption tests with PVP/DVB and Tol/DVB ratios of 0.5 and 1.5, respectively. The betalains were recovered strongly from the red beet juice via the packed bed adsorption column system filled with KOD-4. Then, column reusability and regeneration were studied. In total, the prepared column system was used five times. Ultimately, the results of this study can lead to wide-scale application of betalain-enriched beetroot extracts in the food, pharmaceutical, and cosmetic industries due to their antioxidant and colourant properties as well as their biological activities.

Bi-functionalized ionic liquid porous copolymers for CO2 adsorption and conversion under ambient pressure

Developing solid materials with high CO2 adsorption capacity and catalytic activity has been a hotspot due to the greenhouse effect. In this work, bi-functionalized ionic liquid 1-vinyl-3-methoxyethyl imidazolium glycinate ([VMOEim][Gly]) was copolymerized with crosslinker divinylbenzene (DVB) to obtain bi-functionalized ionic liquid porous copolymers P(nDVB-[VMOEim][Gly]) and HP(nDVB-[VMOEim][Gly]). These copolymers possess loose stack of small particles or laminates, and they contain mesopores and a small number of micropores. For HP(0.6DVB-[VMOEim][Gly]), surface area reaches up to 508 m2·g−1 and the initial decomposition temperature is about 180 °C. Then these porous copolymers were applied for CO2 adsorption at 25 °C and cycloaddition reaction of CO2 with epichlorohydrin under ambient pressure and cocatalyst-free condition. The maximum CO2 capture capacity is 64.5 mg/g with HP(0.6DVB-[VMOEim][Gly]) as adsorbent. The effects of catalyst type, catalyst dosage, reaction time and temperature on the yield of cyclic carbonate were also investigated. The optimum conditions are 4 wt% of HP(0.6DVB-[VMOEim][Gly]) (based on the epichlorohydrin) as catalyst at 130 °C for 10 h, and the yield of 4-(chloromethyl)-1,3-dioxolan-2-one can reach 94%. Furthermore, the catalytic activity of HP(0.6DVB-[VMOEim][Gly]) maintains and the yield is 91% after five-cycle experiment. The mechanism of cycloaddition reaction was also discussed.

Faz Değiştiren Madde Olarak n-Hekzadekan Esaslı Mikrokapsüllerin Hazırlanması, Karakterizasyonu ve Isıl Performansının T-Kayıt Yöntemiyle Belirlenmesi

Faz değiştiren maddeler (FDM’ler), ısıl enerjinin gizli ısı olarak depolanabilmesine olanak sağlayan, sıvıdan katıya ya da katıdan sıvıya faz değişimi esnasında büyük miktarda ısının depolanmasına veya salınmasına izin veren yeni nesil enerji depolama malzemeleridir. FDM’lerin faz değişimi esnasında belirli bir hacimde tutmak amacıyla makro veya mikro/nano ölçekte kapsüllenmeleri gerekmektedir. Kapsülleme işlemi sayesinde malzemenin dış çevrelerden etkilenme derecesi azaltıldığı gibi malzemenin katıdan sıvıya geçişi esnasında mevcut kabuk hacminde sabit tutulması mümkün olmakta ve ısı transfer yüzeyi de arttırılmaktadır. Bu çalışmada, organik FDM’ler sınıfında yer alan bir parafin olan ve binalarda iç ortamın ısıl konforunun sağlanması hususunda uygun faz değişim sıcaklık aralığı sayesinde ısı depolama malzemesi olarak kullanım potansiyeli bulunan n-hekzadekan (n-HD), faz inversiyon emülsifikasyonu yöntemiyle mikro boyutta kapsüllenmiştir. Faz dönüşümü esnasında sızdırma problemi nedeniyle doğrudan uygulamalarda kullanımı uygun olmayan n-hekzadekanın kapsülleme işleminde, kabuk olarak binalarda yalıtım amaçlı sıklıkla kullanılan stiren (St) ve çapraz bağlayıcı divinilbenzen (DVB) kullanılmıştır. Elde edilen mikrokapsüllerin ısıl özellikleri diferansiyel taramalı kalorimetre (DSC) ve Termogravimetrik Analiz (TGA) ile incelenirken, morfolojik özellikleri ve kimyasal yapısı ise sırasıyla Taramalı Elektron Mikroskobu (SEM) ve Fourier Dönüşümlü Kızılötesi (FT-IR) spektroskopisi ile belirlenmiştir. Elde edilen mikrokapsüllerin erime entalpisi 131,074 J/g olarak bulunurken, FDM içeriği %68,55 olarak hesaplanmıştır. Mikrokapsüllenmiş FDM’nin (MikroFDM) ve saf n-hekzadekanın ısı depolama özellikleri ısıtmalı-soğutmalı sirkülasyonlu bir banyo sisteminde karşılaştırmalı olarak test edilmiştir. T-Kayıt yöntemiyle gerçekleştirilen ölçümlerde elde edilen ısıl özellikler DSC analizinden elde edilen sonuçlarla karşılaştırmalı olarak sunulmuştur. N-hekzadekan faz değişim maddesini içeren mikrokapsüllerin sahip oldukları boyut aralığı, faz değişim sıcaklık aralığı, ısı depolama kapasitesi ve gösterdikleri ısıl performans açısından binalarda iç mekan uygulamalarında ısıl konforun sağlanması noktasında kullanımının uygun olduğu ve binalarda enerji tasarrufu açısından önemli kazanımlar sağlayabilecekleri öngörülmüştür.

Preparation and optimization of thorium selective ion imprinted nonwoven fabric grafted with poly(2-dimethylaminoethyl methacrylate) by electron beam irradiation technique

2-dimethylaminoethyl methacrylate (DMAEMA) was grafted onto PP/PE non-woven fabrics (NWF) using pre-radiation graft polymerization technique and subsequent mutual radiation crosslinking with divinylbenzene (DVB). The ion-imprinted polymer (IIP) was synthesized by DVB crosslinking with DMAEMA and thorium complex through radiation. Non-imprinted polymer (NIP) was prepared with the same conditions but utilizing pure DMAEMA instead of DMAEMA-Thorium complex. The NWF, DMAEMA-grafted-NWF, IIP and NIP were characterized with Field Emission Scanning Electron Microscopy (FESEM), Fourier Transformed Infrared Spectroscopy (ATR-FTIR), Thermogravimetric Analyzer (TGA), X-ray photoelectron spectroscopy (XPS), and X-ray Diffraction (XRD). The grafting process parameters were optimized prior to radiation crosslinking with DVB. The effects of DMAEMA concentration and reaction temperature as a function of different irradiation doses were investigated in order to attain optimal grafting conditions. The effects of DVB concentration, process temperature and radiation dosage on the degree of crosslinking were examined. In addition, the effects of crosslinking percentage, initial thorium concentration and concentration of imprinted thorium to the selectivity of IIP and NIP were also determined. The thorium selectivity of both IIP and NIP was measured using batch mixed ions system by inductively coupled plasma mass spectrometry (ICP-MS) analysis. Instead of simultaneous grafting and crosslinking process in bulk along with imprint template, this current study conciliates all grafting, imprint template and crosslinking process independently. Thus, the originality of the research is attributed to individuality grafting and crosslinking technique using ion beam irradiation to obtain IIP of high thorium selectivity without compromising the chemical and physical properties of the adsorbent.

Synergistic catalysis of one-pot cascade reactions by acidic and basic binary porous polymers

Acidic and basic porous polymers were facilely prepared through the radical copolymerization of target monomers and the crosslinker divinylbenzene (DVB), respectively. Combination of these polymers endowed highly efficient, heterogeneous recyclable acid-base binary catalysts for cascade deacetalization-Knoevenagel reaction, offering high yield and stable reusability. Binary polymers with strong acid sites and superior base sites afforded an unprecedented turnover frequency (TOF) in the condensation of benzaldehyde dimethylacetal and nitriles (285 h−1 for malononitrile and 57 h−1 for inert methylene substrate ethyl cyanoacetate). The excellent synergistically catalytic performance was ascribed to the unique self-protection effect of the in-situ formed acid and base sites embedded in the polymeric network. This study provided a facile, versatile and efficient strategy towards acid-base bifunctional heterogeneous catalysts by combining acidic and basic porous polymers.

New Composite Proton-Conducting Membranes Based on Nafion and Cross-Linked Sulfonated Polystyrene

New composite membranes based on commercial perfluorinated Nafion-115 membrane and cross-linked sulfonated polystyrene were synthesized and investigated. The membranes were prepared by radical polymerization of styrene in the presence of a cross-linking agent divinylbenzene in Nafion polymer matrix and subsequent sulfonation of formed polystyrene. The membranes containing approximately 5 and 10 wt % of cross-linked polystyrene with ion-exchange capacity of 1.1 to 1.3 mg-eq/g were obtained. Modification with sulfonated polystyrene leads to an increase in the moisture content and proton conductivity of membranes in the humidity range of 15 to 100 RH.