Methacrylic Esters Research Articles

Bactericidal and Antifouling Coatings with the "Killing-Repelling-Killing" Triple Function Based on Cationic Copolymers with Structure Conversion and Capsaicin Analogue Release.

The capsaicin analogue N-(4-hydroxy-3-methoxybenzyl) acrylamide (HMBA) was linked with polylauryl methacrylate-b-poly(2-(N,N-dimethylamino)ethyl methacrylate) (PLMA-b-PDMAEMA) via a quaternization reaction with 4-(acrylamidomethyl)-2-methoxyphenyl 2-chloroacetate (AAMPCA). The amphiphilic copolymers were capable of transforming its structure in response to the solvent change from aprotic to protic, which was verified by the 1H NMR spectrum. The resulting cationic copolymers underwent a hydrolysis process in water, yielding zwitterionic groups on surfaces. Meanwhile, the bactericidal reagent HMBA was released. It was proved that the hydrolysis rate of the copolymers accelerated with higher temperature, higher pH value, and higher hydrophilic block units. And the controllable, sustainable release of HMBA was achieved with copolymer-mediated hydrolysis. Protein-repellent and bactericidal tests on the surface of the coating proved that antifouling and bactericidal performances of the coating correlated to the structure conversion abilities of the corresponding copolymer. The dynamic monitoring of Escherichia coli adhesion in 3 h evidenced the antifouling and bactericidal process of copolymers with different block ratios and concentrations. The coating incorporated with 3% PLMA120-b-(PDMAEMA-AAMPCA)120 in polylactic acid base materials showed an adhesion ratio of E. coli less than 1% within 1 h, and the survival ratio of the adhered bacteria is <1%, suggesting its rapid speed and high efficiency in "bacterial repelling and killing". Also, the PLMA120-b-(PDMAEMA-AAMPCA)120 copolymer demonstrated enhanced bactericidal ability compared with the mixture of cationic poly(laruyl methacrylate)120-b-poly(carboxybetaine methacrylate ester)120 (PLMA120-b-PCBMAE120) and free HMBA. The lowest minimal inhibitory concentration was 0.078 mg/mL against Staphylococcus aureus and 0.312 mg/mL against E. coli, respectively.

Synthesis and properties of biomass‐based polymethacrylate comprising chitin‐derived 2‐acetamide‐2‐deoxyisosorbide as a repeat unit

AbstractSynthesis and applications of biobased polymers have been extensively studied in order to reduce the use of petroleum‐based polymers and likewise environmental load. Several biobased polymers have been produced on a commercial large scale to date. However, the lineup of biobased high‐performance polymers with transparency and high glass transition temperature is inadequate and their development is a critical issue. In this article, we design a new biobased polymethacrylate comprising rigid cis‐fused bicyclic 2‐acetamide‐2‐deoxyisosorbide (ADI) as a repeat unit. We have recently invented catalytic transformation systems from chitin as a marine biomass to ADI as a new nitrogen‐containing platform chemical. The ADI‐based polymethacrylate is synthesized via free radical polymerization of the methacrylic acid ester of ADI initiated by (NH4)2S2O8 and N,N,N′,N′‐tetramethylethylenediamine in dimethylsulfoxide–H2O mixed solvent. The molecular weight and its dispersity are estimated by size exclusion chromatography on the basis of polymethylmethacrylate standards. UV–visible spectroscopy demonstrates the high transparency of the polymer in the visible wavelength region. Differential scanning calorimetry analysis of the polymer clarifies the remarkably high glass transition temperature, compared with that of polymethylmethacrylate. The thermal decomposition temperature of the polymer is also evaluated by thermogravimetric analysis. On the basis of the favorable properties of the ADI‐based polymer, the present study proposes it as a nitrogen‐containing biobased polymer useful for real‐world applications. © 2024 Society of Chemical Industry.

Preparation of an adsorptive membrane of polyvinylidene fluoride incorporated functionalized boron nitride nanosheets for arsenic removal

Incorporating nanomaterials into membranes will enhance wastewater treatment efficiency with their unique characteristics, such as higher permeability, thermal stability, surface roughness, hydrophilicity, and fouling control. In this study, the surface modified boron nitride with phosphoric acid 2-hydroxyethyl methacrylate ester (PA/BN) was grafted with polyethylene glycol (PEG) via conventional grafting. The PEG grafted PA/BN (PEG-g-PA/BN) melt blended with polyvinylidene fluoride (PVDF) resin by using an internal mixer at different mass percentages (100% PVDF (PVDF), 3% PEG-g-PA/BN + 97% PVDF (97:3 BN), 5% PEG-g-PA/BN + 95% PVDF (95:5 BN), 7% PEG-g-PA/BN + 93% PVDF (93:7 BN), and 7% PEG-g-PA/BNNS + 93% PVDF (93:7 BNNS). Phase inversion technique was used to cast the blended mixture into a thin membrane. The prepared membranes were analyzed with different characterization techniques to determine chemical composition, crystallinity, morphology, and thermal properties. The prepared composite membrane was evaluated in terms of water permeability, anti-fouling resistance, and solute rejection efficiency with deionized water, bovine serum albumin, and arsenic solution as well. PVDF membranes show high water flux and porosity. The water flux and porosity of the blends decrease as the percentage of PEG-g-PA/BN increases. However, the highest removal capacity for arsenic was observed at 93:7 BN. The adsorption of arsenic ions takes place via complexation with PA/BN in the PVDF matrix. This was confirmed with field emission scanning electron microscopy–energy-dispersive X-ray analysis and X-ray photoelectron spectroscopy analyses.

Enzyme‐Responsive Polyion Complex Nanoparticles of Cationic Antimicrobials for Activatable Antibacterial Therapy

AbstractA self‐assembled “caging” strategy is presented for the safe delivery of potent cationic antimicrobials that suffer from non‐specific toxicity for the effective treatment of in vivo systemic bacterial infection. The key development here is a new block copolymer consisting of a poly(ethylene glycol) (PEG) stealth block and an anionic and lipase‐degradable block of poly(ɛ‐caprolactone) (PCL) and phosphonic acid‐bearing methacrylate copolymer, synthesized by hybrid copolymerization of methacrylate and cyclic esters. The anionic blocks electrostatically interact with cationic antimicrobials to form neutrally charged polyion complexes with the PEG blocks on the surface. The PCL component imparts the nanocomplex with biodegradability by bacterial secretory lipase. In the proof‐of‐concept study, cationic polyimidazolium that shows excellent antibacterial activity but severe toxicity is packaged by the block copolymer into nanocomplexes, which are stable in complex environments of high salt and protein concentrations and released the antimicrobials upon degradation of the copolymer by bacteria‐secreted lipase. The “caging” formulation of polyimidazolium eliminated its toxicity and led to highly effective bactericidal performance comparable to free polyimidazolium. This caging strategy does not require sophisticated chemical modification of cationic antimicrobials, offering a broadly applicable formulation strategy to overcome their common toxicity issue that has become a primary translational barrier.

Underwater adhesive bonding for offshore structure maintenance and repair

ABSTRACT For maintenance and repair of offshore structures, such as wind turbines, onsite assembly is essential. Currently, secondary elements such as sensors, safety conductor supports, and cathodic protection are welded or screwed to the primary offshore structure, which itself is coated to be protected against maritime stressors such as corrosion induced by sea water. Because of the welding or screwing processes, complex and costly post-treatments are unavoidable for safe operation during the lifetime of the offshore structures. Thus, welding operations for example require the coating to be removed and recoated to provide full corrosion protection. In this study the disadvantages resulting from the state-of-the-art joining processes were addressed in order to be avoided by application of adhesive bonding technology. For this purpose, thermal and mechanical characterisation of two structural two-component (2K) adhesive systems under influence of maritime conditions were carried out. For this purpose, an epoxy adhesive and a methacrylate ester adhesive were analysed. In addition to water absorption and glass transition temperatures, tensile properties as a function of curing were also analysed, as these properties are essential to ensure the reliability and long-term stability of the bond. The adhesive bonds were tested at tensile shear level. Inductive curing of the adhesive was investigated to ensure both adhesive application and removal in a single 30-minute immersion in marine environment. The present work highlights the fundamental challenges of bonding under water in combination with inductive rapid curing of adhesive systems.

Hydrophobic Aerogels from Vinyl Polymers Derived from Radical Polymerization: Proof-of-Concept.

Hydrophilicity is one important drawback of bio-based aerogels. To overcome this issue, a novel approach for the preparation of mesoporous, water repellent aerogels is introduced, which combines synthesis of cross-linked bio-based copolymers from methacrylate copolymerizations, followed by solvent exchange and supercritical drying steps. The influence of monomers with different nonpolar ester groups (methyl, vanillin, tetrahydrofurfuryl) on textural properties and water contact angles of the dry products is assessed. Final aerogels show generally high overall porosities (≈96%), low densities (0.07-0.11gcm-3) as well as fine, mainly mesoporous networks, and specific surface areas in the range of 120-240m2g-1. Hereby, choice of the methacrylate ester groups results in differences of the resulting pore-size distributions. Water repellency tests show stable static water contact angles in the hydrophobic range (≈100°) achieved for the substrate containing the vanillin ester group. On the contrary the other substrates absorb water quickly, which indicates a decisive role of the ester group. The presented approach opens up a new pathway to bio-based aerogels with intrinsic hydrophobicity. It is suggested that the properties are tailored by the choice of the monomer structure, hence enabling further adaption and optimization of the products.

From Facile One-Pot Synthesis of Semi-Degradable Amphiphilic Miktoarm Polymers to Unique Degradation Properties.

We report a one-pot synthesis of well-defined A5B and A8B miktoarm star-shaped polymers where N,N-dimethylaminoethyl methacrylate (DMAEMA) and various cyclic esters such as ε-caprolactone (ε-CL), lactide (LA) and glycolide (GA) were used for the synthesis. Miktopolymers were obtained by simultaneously carrying out atom transfer radical polymerization (ATRP) of DMAEMA, ring-opening polymerization (ROP) of cyclic esters, and click reaction between the azide group in gluconamide-based (GLBr5-Az) or lactonamide-based (GLBr8-Az) ATRP initiators and 4-pentyn-1-ol. The relatively low dispersity indices of the obtained miktoarm stars (Đ = 1.2-1.6) indicate that control over the polymerization processes was sustained despite almost complete monomers conversions (83-99%). The presence of salts from phosphate-buffered saline (PBS) in polymer solutions affects the phase transition, increasing cloud point temperatures (TCP) values. The critical aggregation concentration (CAC) values increased with a decreasing number of average molecular weights of the hydrophobic fraction. Hydrolytic degradation studies revealed that the highest reduction of molecular weight was observed for polymers with PCL and PLGCL arm. The influence of the composition on the miktopolymers hydrophilicity was investigated via water contact angle (WCA) measurement. Thermogravimetric analysis (TGA) disclosed that the number of arms and their composition in the miktopolymer affects its weight loss under the influence of temperature.

Electron beam-assisted exfoliation of boron nitride and covalent functionalization

A facile, scalable exfoliation technique is still required for further modification to cater to any potential application for two-dimensional boron nitride. This paper discusses the radiation-assisted exfoliation of hexagonal boron nitride (h-BN) using electron beam irradiation and followed by functionalization with phosphoric acid 2-hydroxyethyl methacrylate ester (PA) to facilitate targeted applications. h-BN is dispersed in NaOH solution and subjected to mild sonication to facilitate ion intercalation between the layers. The sonicated h-BN solution was exposed to electron beam irradiation for BNNS exfoliation. The degree of exfoliation was measured in terms of d-spacing derived from XRD using Bragg's law. The effect of irradiation dose, energy, NaOH concentration, and mass of h-BN, on exfoliation degree was investigated. XRD analysis was used to compute the d-spacing, crystallinity, and crystal size of h-BN after irradiation. The d-spacing attained for pristine h- BN was 0.334 nm, however it increases to 0.337 nm upon irradiation at 100 kGy doses, 3 MeV of energy, and 0.1 g of h-BN in 80 mL of 30 % NaOH solution. The occurrence of radiation-assisted exfoliation and its mechanism were supported by FTIR, TGA, Raman, FESEM, XPS, AFM, and TEM analyses. The exfoliated BN was functionalized with PA. The degree of functionalization was measured by phosphoric density (mmol/g) via the acid-base titration method. The effect of PA concentration, reaction temperature and mass on phosphoric density was also investigated. The highest phosphoric density attained was approximately 13.32 mmol/g at 10 % PA, 0.1 g of exfoliated BN, 80 °C, and 5 h. The incorporation of PA onto exfoliated BN was further confirmed by XRD, FTIR, TGA, Raman, FESEM-EDX, and XPS analyses. Conclusively, this study reveals a facile dual-step exfoliation and functionalization technique of h-BN nanosheet through radiation assisted exfoliation technique.

Copolymerization kinetics of hydrogels based on oligo(ethylene glycol) methacrylates and acrylic acid using isoconversional methods

Monomers consisting of a methacrylate moiety attached to a short poly(ethylene glycol) (PEG) chain can be polymerized to form hydrogels with several applications such as the removal of dyes and heavy metals from wastewater. In this study, the radical copolymerization kinetics of oligo(ethylene glycol) methyl methacrylate (OEGMMA), and oligo(ethylene glycol) hydroxyethyl methacrylate (OEGHEMA), with acrylic acid (AAc) was investigated. In both cases, hydrogels were formed with cross-linked structure. The rate of polymerization and degree of conversion were measured using differential scanning calorimetry (DSC) operating under non-isothermal conditions, at several constant heating rates, or under isothermal conditions, at different constant reaction temperatures. Isoconversional kinetics were employed to estimate the effective activation energy of the polymerization. It was found that, in the homopolymer (POEGHEMA) bearing hydroxyl groups, polymerization under both isothermal and non-isothermal conditions proceeds faster compared to the polymer with methoxy groups (POEGMMA). This behavior is attributed to the interaction between the hydrogen in the hydroxyl group with the carbonyl oxygen of the methacrylic ester, which results in a reduction of the electron density at the double bond and therefore increases its reactivity. Monomer–monomer association through hydroxyl groups results in initially lower activation energy of POEGHEMA. As polymerization proceeds, the existence of aggregated hydroxyl structures in the POEGHEMA macromolecular chains result in higher activation energies and a more abrupt increase in the conversion time curve. The addition of acrylic acid results in higher copolymerization rates for both methacrylates, with P(OEGMMA-AAc) affected more, since in the case of OEGHEMA specific functional (i.e. hydroxyl) groups already exist in the macromolecules. The association of monomer-AAc through hydroxyl‑carbonyl groups, results in lower activation energies for both copolymers compared to the corresponding homopolymers. The significant contribution of isoconversional methods in the study of polymerization kinetics of hydrogels it was thus verified.

Fabrication of polyethyleneimine grafted maleopimaric acid glycidyl methacrylate ester stationary phase for mixed-mode liquid chromatography

Due to their advantages of low green toxicity, diverse sources, renewable nature, and excellent biocompatibility, natural products have been extensively utilized in the exploration and development of novel stationary phase materials for liquid chromatography. In this study, we fabricated a rosin-based stationary phase material for mixed-mode chromatography by utilizing maleopimaric acid glycidyl methacrylate ester (MPAG) and polyethyleneimine (PEI) as ligands. Initially, silica was functionalized with MPAG through thiol-ene click reaction, followed by the grafting of PEI via an imidization reaction to produce Sil-MPAG-PEI material. This material exhibited both anion exchange and hydrophilic interaction properties due to the presence of PEI, allowing for the switching of its retention mode from reversed-phase mode to a mixed-mode incorporating reversed-phase, hydrophilic interaction and ion-exchange chromatography (RPLC/HILIC/IEC) under different mobile phase conditions. Consequently, Sil-MPAG-PEI demonstrated the ability to provide various interactions, including hydrophobic, π-π, hydrogen bond, hydrophilic, ion exchange, and electrostatic interactions. These interactions enabled selective separation among compounds with different polarities, such as nucleosides/bases, benzoic acids, flavonoids, alkylbenzenes, phenols, anilines, and polycyclic aromatic hydrocarbons (PAHs). Furthermore, Sil-MPAG-PEI demonstrated excellent chromatographic stability, as evidenced by the low relative standard deviations (RSDs) of the retention time for interday precision and interday precision were 0.042 %-0.275 % (n = 10) and 0.159 %-0.932 % (n = 7). The column was also successfully employed for the quantitative determination of evodiamine and rutaecarpine in an extract solution of Evodiae fructus, achieving concentrations of 9.102 and 3.256 mg/g, respectively. These results demonstrate the potential of Sil-MPAG-PEI in the analysis of complexsamples. Briefly, this study investigated and confirmed the potential application of rosin derivatives in mixed-mode liquid chromatography separations has been investigated and verified. The exceptional separation ability of Sil-MPAG-PEI indicates that it is a promising separation material for chromatographic separation.

Армированные композитные материалы на основе фосфорсодержащих связующих с перспективными физико-механическими и пожаробезопасными свойствами

In this work, a comparative analysis of the properties of glass fiber-reinforced epoxy resin (ED-20) composites and composites based on glass fiber-reinforced phosphorus-containing ester methacrylate oligomers (PEAO) was carried out. Reinforced fiberglass plastics made on the basis of PEAO have demonstrated promising fireproof characteristics, especially in limited oxygen index and smoke emission tests. It is also worth noting that the mechanical properties of materials based on phosphorus-containing ester-acrylate resins are outstanding. The samples of a widely used glass fiber reinforced epoxy resin ED-20 with 9,10-dihydro-9-hydroxy-10-phosphaphenanthrene-10-oxide-4,4`-diaminodiphenylmethane (DDM-DOPO) additive demonstrated lower flammability compared to the samples without fire retardant additives. A mixture of DDM-DOPO and graphene added to the samples led to a low smoke generation rate of the samples; however, the rate was 1.5-2 times higher than that of the samples based on phosphorus-containing ester methacrylate resins. The addition of fire retardants has reduced the mechanical properties of fiberglass plastics based on epoxy resin, which can be a problem for the use of these materials in the aviation industry. These results clearly show better prospects of using fiberglass-reinforced plastics based on phosphorus-containing ester methacrylate oligomers in comparison with modified plastics based on the widely used epoxy resin.

The Categories and Application of PCE Superplasticizers in Concrete

Polycarboxylate ether superplasticizers (PCEs) are water reducers in the concrete mix that play a significant function in aspects of reducing the water-to-cement ratio, improving impermeability, increasing compressing strength, and meditating the shrinkage. This paper introduces the characteristics of PCEs, discusses the application, advantages, and disadvantages of concrete, and puts forward some measures. The mechanism of PCEs is the dispersion function of the molecular structure and the neutralization. Currently, PCEs are updated from one generation to another, conventional PCEs mainly include methacrylate ester, isoprenol ethe, and methallyl ether-PCEs. Another two major types of PECs are vinyl ether-based and calcium silicate hydrates PCEs, respectively. The application of PCEs revolutes novel types of concrete, such as ultra-high performance concrete and self-compacting concrete. When applying PCEs, retardation has to be considered. Meanwhile, another drawback of PCEs is that they can hardly work with other admixtures. A novel type that is considered clay properties can be another research field.

Boronate affinity-based surface molecularly imprinted polymer microspheres using polyethyleneimine/dopamine coating for efficient selective recognition and separation of Ginsenoside Rb1

A novel approach combining boronate affinity with surface molecular imprinting was developed for the specific recognition and separation of ginsenoside Rb1. Firstly, the boronic acid-functionalized polymer microspheres were prepared as inner cores via suspension polymerization using methyl methacrylate, ethyleneglycol dimethacrylate, and 4-vinylphenyl boronic pinacol ester (4-VBPE) as polymerization monomers. Then, the Ginsenoside Rb1 (GRb1) template was covalently pre-anchored onto the surface of microspheres through boronate affinity binding after the hydrolysis of 4-VBPE. Finally, dopamine and polyethyleneimine were used as co-coating monomers to form a thickness-controllable imprinting layer onto the polymer microspheres via in-water self-copolymerization. The key factors affecting specific recognition, including the boronic acid content, adsorption media, and polymerization time were carefully optimized. The resulting molecularly imprinted microspheres (MIMs) exhibited strong surface hydrophilicity. In the aqueous media, the optimal adsorption capacity for the template reached 81.45 μmol g−1, and the imprinting factor was 5.32. The specific evaluation showed that the MIMs had a much higher selectivity for GRb1 than its analogues, and the selectivity coefficients were all higher than 2.4. In addition, the MIMs can be applied as adsorbents for solid-phase extraction to selectively separate ginsenosides from American ginseng extract. The eluting recovery ratios of GRb1, GRg2, and GRd reach 92.39%, 88.90%, and 92.49%, respectively.

Self-healing poly(oxime–carbamate) films with tunable mechanical properties derived from rosin

Thermoset polymers with superior dimensional stability and creep resistance have been widely used in various electronic and energy devices. However, they are difficult to reprocess and recycle, and with the gradual decrease in nonrenewable resources, there is an urgent need for new sustainable materials as alternatives to thermoset polymers. Polymer materials with self-healing properties can provide high durability and sustainability for devices. In this work, we prepared a series of rosin-based poly(oxime–carbamate) films by reacting rosin acrylate/glycidyl methacrylate ester with toluene 2, 4-diisocyanate using dimethylglyoxime as the chain extender and triethanolamine as the crosslinking agent. The introduction of rosin with a rigid tricyclic phenanthrene structure in the prepared films resulted in excellent tensile strength (4.9 ± 0.03 MPa) while maintaining high elongation at break (973.2 % ± 4.8 %) and toughness (20.9 ± 0.1 MJ m−3). The good self-healing properties of the prepared films (90.6 % ± 1.5 %, 60 °C for 3 h) were attributed to the introduction of dynamic oxime–carbamate bonds. In particular, the tunable mechanical and self-healing properties of the films can be achieved by varying the molar ratio of rosin acrylate/glycidyl methacrylate ester to dimethylglyoxime. Furthermore, the prepared rosin-based films exhibited good adhesion, welding, and anticorrosion properties. Considering the reversible exchange mechanism of dynamic oxime–carbamate bonds and their use in self-healing and recycling applications, a new strategy for developing sustainable high-performance biobased self-healing coatings is presented.

Controlled synthesis and solution properties of copolymers of methacrylic esters and ammonium-containing methacrylamide

Copolymers based on oligo(ethylene glycol) methacrylate, dodecyl methacrylate, and the cationic monomer N-methacryloylaminopropyl-N,N-dimethyl-N-propylammonium bromide have been obtained by reversible addition−fragmentation chain-transfer polymerization in high yields and in a controlled mode. The influence of the composition of the obtained polymers on the solubility in water and organic solvents, distribution in the water-octanol system, and interfacial tension at the water-oil interface is shown. The presence of thermoresponsive properties for polymers in water was found, and their aggregation in aqueous media was also studied.

Methacrylate Ester Monomers.

The Expert Panel for Cosmetic Ingredient Safety reviewed newly available studies since their original assessment in 2005, along with updated information regarding product types and concentrations of use, and confirmed that these 22 methacrylate ester monomers are safe as used in nail enhancement products in the practices of use and concentration as described in this report, when skin contact is avoided.

CO2 emission of polycarboxylate superplasticizers (PCEs) used in concrete

At an annual production of ∼15 million tons, polycarboxylate (PCE) based superplasticizers (cement dispersants) present the most widely used concrete admixture. In this paper, their carbon footprint was quantified considering the three most common kinds of PCE polymers, namely methacrylate ester (MPEG), methallyl ether (HPEG) and isoprenol ether (IPEG) based PCEs produced in four major manufacturing countries: EU-27, US, Japan and China. A cradle-to-gate approach was applied to estimate CO2 emissions from raw materials extraction to PCE fabrication. On this basis, and depending on their chemical composition and country-specific electricity grid CO2 emission factors, their carbon footprints were calculated. The results show a strong dependence on the kind of PCE, their structural design as well as the producing country. For all PCEs, the main components ethylene oxide, unsaturated acids (methacrylic/acrylic acid) and NaOH were found to be mainly responsible for the entire CO2 footprint. The average total CO2 emissions of the three kinds of PCEs vary between 2.98 ± 0.54 kg CO2/kg (MPEG), 2.48 ± 0.48 kg CO2/kg (HPEG), and 2.40 ± 0.47 kg CO2/kg (IPEG). Evidently, MPEG PCEs reveal the highest footprint which is owed to methacrylic acid whereas HPEG and IPEG PCEs contain acrylic acid. The range of total CO2 emissions is caused by significant differences in the carbon footprints of the electrical grids in various countries. An impact study revealed that at common field dosages the contribution of PCEs to the CO2 balance of a standard concrete (CO2 footprint ∼ 300 kg CO2/m3) varies between approx. 3 and 22 kg CO2/m3 in Europe, with ready-mix type PCEs contributing more than precast concrete PCEs. Furthermore, it is demonstrated that the CO2 footprint of PCE superplasticizers can be reduced by almost 80% if predominantly renewable energy is used in the chemical industry.

Investigations on Stability of Polycarboxylate Superplasticizers in Alkaline Activators for Geopolymer Binders.

Calcined clays are interesting starting materials to be used as SCMs (supplementary cementitious materials) in cements or to be converted to geopolymers by activation with a high alkaline activator. The adjustment of the properties in the fresh state, especially regarding the consistency of these binders, is almost exclusively achieved by the addition of water, since commercially available superplasticizers seem to be ineffective in low-calcium geopolymer systems. The aim of this study was a systematic investigation of various PCE (polycarboxylate ester/ether) superplasticizers (methacrylate ester PCE: MPEG, isoprenol ether PCE: IPEG, methallyl ether PCE: HPEG) with respect to their stability in different alkaline activators (NaOH, KOH, sodium and potassium silicate solutions). The effectiveness of superplasticizers (SPs) in low-calcium geopolymer binders was verified by rheological tests. Size exclusion chromatography was used to investigate if structural degradation of the superplasticizers occurs. The investigated PCE superplasticizers showed a thickening effect in the low-calcium geopolymer system. Depending on the alkalinity of the activator solution, a degradation process was detected for all the PCEs investigated. The side chains of the PCEs are cleaved off the backbone by basic ester and ether hydrolysis. The highest degree of degradation was found in sodium and potassium silicate solutions. In alkaline hydroxide solutions, the degradation process increases with increasing alkalinity.

CO2 responsive self-standing Pickering emulsion gel stabilized with rosin-based surfactant modified cellulose nanofibrils

Emulsion gel was developed to provide desirable texture, palatability and functionality to food products. Tunable stability of emulsions is often desired, as in certain situations, the chemical content release usually relies on emulsion induced destabilization of the droplet. However, the destabilization for emulsion gel is difficult because of the formation of highly entangled networks. To address this issue, a fully biobased Pickering emulsion gel stabilized by cellulose nanofibrils (CNF) modified with a CO2 responsive rosin-based surfactant, maleopimaric acid glycidyl methacrylate ester 3-dimethylaminopropylamine imide (MPAGN) was reported. The emulsification/de-emulsification can be reversibly regulated because this surfactant has sensitive CO2 responsive property. MPAGN can be reversibly between active cationic (MPAGNH+) and inactive nonionic (MPAGN) responsive to CO2 and N2. The microstructure of the emulsion gel was observed and compared before and after the response. The rheological properties of emulsion gel stabilized by different concentrations of MPAGNH+ and different contents of CNF were studied separately. As 0.2 wt% CNF was dispersed in 1 mM MPAGNH+ solution, the obtained emulsion can be self-standing for long duration. The rheology study indicated that these emulsions show typical gel characteristics with shear-thinning behavior. The stabilization mechanism of these gel emulsion is a synergistic effect caused by the combination of CO2 responsive Pickering emulsion and intertwined network caused by the hydrogen-bond interaction among CNF.

Improved selectivity of molecularly imprinted polymers based on the synergistic action of hydrogen bond and electrostatic interaction.

Based on the synergistic action of hydrogen bond and electrostatic interaction, provided by methacrylic acid and 2-aminoethyl ester hydrochloride (FM2), respectively, novel molecularly imprinted polymers (SA-MIPs) were designed to improve its selective recognition ability. Diclofenac sodium (DFC) was chosen as the template molecule of this study. The interaction and their recognition sites between two functional monomers and templates were confirmed by nuclear magnetic resonance hydrogen spectroscopy. Because of the synergistic action of hydrogen bond and electrostatic interaction, the imprinting factor (IF) of SA-MIPs (IF = 2.26) is superior to the corresponding monofunctional monomer imprinting materials (IF = 1.52, 1.20) and the materials using two functional monomers with an only single type of interaction (IF = 1.54, 1.75). The results of selective adsorption experiments indicate that the selective recognition ability of SA-MIPs is significantly better than that of the other four MIPs, and the difference in selectivity coefficient for methyl orange is the largest between SA-MIPs and the MIPs only using FM2, which is about 70 times. In addition, x-ray photoelectron spectroscopy was used to verify the interaction between SA-MIPs and the template. This work and its explanation of the interaction mechanism at the molecular level will be helpful for the rational design of novel MIPs with higher selectivity. Besides, SA-MIPs have good adsorption performance (37.75 mg/g) for DFC in aqueous solutions, which could be used as potential adsorption materials for the effective removal of DFC in the aquatic environment.