Types Of Monomers Research Articles

The effect of diamine structure on the chemical stability of polyamide nanofiltration membranes: Experimental and density functional theory studies

Monomers are elementary units that constitute the polyamide layer, which determines the properties of nanofiltration membranes. The design of nanofiltration membranes with both high separation performance and outstanding chemical stability remains a challenge. In this study, two typical monomers, heterocyclic monomer molecule-piperazine (PIP) and carbon ring molecule-1,4-cyclohexane diamine (CHDA), were applied as aqueous monomers for interfacial polymerization to generate polyamide nanofiltration membranes. The physicochemical properties of the two nanofiltration membranes were comprehensively investigated. The results demonstrated that the nanofiltration membrane fabricated via CHDA exhibited more chemical stability than that fabricated via PIP. The mechanisms influencing the chemical stability difference were elucidated via multiscale simulation. The CHDA polyamide has higher levels of HOMO-LUMO energy and Gibbs-free energy, which make it more stable under harsh chemical environments. Overall, this work presents the effect of the diamine structure on the chemical stability of polyamide NF membranes, which can inspire highly chemically stable nanofiltration membrane fabrication.

Biodegradable Polyhydroxyalkanoates with a Different Set of Valerate Monomers: Chemical Structure and Physicochemical Properties.

The properties, features of thermal behavior and crystallization of copolymers containing various types of valerate monomers were studied depending on the set and ratio of monomers. We synthesized and studied the properties of three-component copolymers containing unusual monomers 4-hydroxyvalerate (4HV) and 3-hydroxy-4-methylvalerate (3H4MV), in addition to the usual 3-hydroxybutyrate (3HB) and 3-hydroxyvalerate (3HV) monomers. The results showed that P(3HB-co-3HV-co-4HV) and P(3HB-co-3HV-co-3H4MV) terpolymers tended to increase thermal stability, especially for methylated samples, including an increase in the gap between melting point (Tmelt) and thermal degradation temperature (Tdegr), an increase in the melting point and glass transition temperature, as well as a lower degree of crystallinity (40-46%) compared with P(3HB-co-3HV) (58-66%). The copolymer crystallization kinetics depended on the set and ratio of monomers. For terpolymers during exothermic crystallization, higher rates of spherulite formation (Gmax) were registered, reaching, depending on the ratio of monomers, 1.6-2.0 µm/min, which was several times higher than the Gmax index (0.52 µm/min) for the P(3HB-co-3HV) copolymer. The revealed differences in the thermal properties and crystallization kinetics of terpolymers indicate that they are promising polymers for processing into high quality products from melts.

Poly(dibenzofuran-p-terphenyl piperidinium)-based anion exchange membranes with enhanced phase separation for water electrolysis

Anion exchange membranes (AEMs) based on non-aryl ether–type poly(aryl piperidinium) have recently drawn significant attention because of their excellent ion exchange capacity (IEC), chemical stability, and ionic conductivity. However, the reactivity of poly(aryl piperidinium) varies significantly depending on the type of monomer used and is also accompanied by very rapid polymerization. These limitations have hindered the development of an AEM with controllable morphology. In the present study, AEMs with the desired morphology were obtained using hydrophilic and hydrophobic monomers; indeed, a well-controlled morphology was achieved even though they were random copolymers. Specifically, hydrophilic dibenzofuran and hydrophobic p-terphenyl were used as raw materials to develop the novel AEM material p(BF-TP)-Pip-x, i.e., a poly(dibenzofuran-p-terphenyl-piperidinium)-based copolymer. The dibenzofuran content relative to p-terphenyl was 5%, 10%, and 30%, resulting in three types of p(BF-TP)-Pip-x-based membranes. Their properties were compared with a poly(p-terphenyl-piperidinium)(pTP-Pip)-based AEM, a homopolymer composed solely of p-terphenyl. p(BF-TP)-Pip-10, a membrane with a dibenzofuran content of 10%, exhibited excellent mechanical properties with a tensile strength of 42 MPa and an elongation of break of 9.7%, along with high ionic conductivity at 144 mS cm−1 at 80 °C, owing to its well-developed, phase-separated morphology. Furthermore, its conductivity retention was 93% after treatment in a 2 M KOH solution at 80 °C for 960 h. For a given IEC, excellent alkaline stability was achieved compared to existing poly(aryl piperidinium)-based AEMs. p(BF-TP)-Pip-10 also exhibited excellent thermal and oxidative stability. In AEM water electrolysis tests, the membrane showed a very high current density of 1309 mA cm−2 at 1.8 V, a 120% improvement over pTP-Pip.

The effect of polymer on the floatation-flocculation performance of flocculant for treating polymer flooding produced water

In this paper, a series of hydrophobically modified polyacrylamide (HMPAM) containing different types of hydrophobic monomer were synthesized. Their effects on the performance of a typical flocculant DA, which was used in air floatation cyclone and is a copolymer of tertiary amine monomer and polymerizable polyether, were investigated. The experimental results showed that low concentration (≤200 mg/L) of HMPAM improved the oil removal performance of DA, and high concentration of HMPAM greatly reduced the oil removal performance of DA. It was proposed that the electrostatic attraction between HMPAM and DA had both the positive and negative effects on performance of DA, and which one dominated was influenced by HMPAM concentration. This propose was confirmed by the results of dynamic light scattering and zeta potential. In addition, we found that the negative effect decreased with the increasing hydrophobic monomer chain. The results of this study can provide a guidance for the synthesis and selection of HMPAM from the perspective of produced water treatment.

Recent Advances in the Support Layer, Interlayer and Active Layer of TFC and TFN Organic Solvent Nanofiltration (OSN) Membranes: A Review.

Although separation of solutes from organic solutions is considered a challenging process, it is inevitable in various chemical, petrochemical and pharmaceutical industries. OSN membranes are the heart of OSN technology that are widely utilized to separate various solutes and contaminants from organic solvents, which is now considered an emerging field. Hence, numerous studies have been attracted to this field to manufacture novel membranes with outstanding properties. Thin-film composite (TFC) and nanocomposite (TFN) membranes are two different classes of membranes that have been recently utilized for this purpose. TFC and TFN membranes are made up of similar layers, and the difference is the use of various nanoparticles in TFN membranes, which are classified into two types of porous and nonporous ones, for enhancing the permeate flux. This study aims to review recent advances in TFC and TFN membranes fabricated for organic solvent nanofiltration (OSN) applications. Here, we will first study the materials used to fabricate the support layer, not only the membranes which are not stable in organic solvents and require to be cross-linked, but also those which are inherently stable in harsh media and do not need any cross-linking step, and all of their advantages and disadvantages. Then, we will study the effects of fabricating different interlayers on the performance of the membranes, and the mechanisms of introducing an interlayer in the regulation of the PA structure. At the final step, we will study the type of monomers utilized for the fabrication of the active layer, the effect of surfactants in reducing the tension between the monomers and the membrane surface, and the type of nanoparticles used in the active layer of TFN membranes and their effects in enhancing the membrane separation performance.

Green synthesis of reactive copolymers in molten ε‐caprolactam solvent and their compatibilizing effects in PA10T/PPO blends

AbstractThe environmentally‐friendly preparation of compatibilizers, especially copolymers with reactive monomers, is essential for developing new polymer blends. In this study, molten ε‐caprolactam was used as a green solvent to copolymerize styrene with three types of reactive monomers, namely maleic anhydride (MAH), glycidyl methacrylate (GMA) and 3‐isopropenyl‐α,α‐dimethylbenzyl isocyanate (TMI). The pure PS and the corresponding copolymers (PSM, PSG, and PST) had relatively high yields of 97.8%, 73.7%, 93.3%, and 96.3%, respectively. Moreover, these synthesized polymers were used as compatibilizers to modify the immiscible PA10T/PPO blends. PSM and PSG showed a positive effect in improving the compatibility of PA10T/PPO blends, reducing the size of PPO domains, and improving the mechanical properties. The long‐term thermal stability of unmodified PA10T and PA10T/PPO blends was investigated. The color changes (∆E) of PA10T, PA10T/PPO blends with the addition of pure PS, PSM, PSG, and PST changed to 46.9, 44.0, 45.2, 44.2, and 45.0 after 5 days of aging. The tensile strength retentions were 24.1%, 54.7%, 63.4%, 67.6%, and 60.0%, respectively. These results suggested that the synthesized PSG and its corresponding PA10T/PPO blend had excellent properties and great potential for the development of high‐performance plastics.

Determination of melamine contamination in milk with various packaging: a risk assessment study.

Melamine is one type of monomer used as starting substance in manufacturing packaging lining in many countries worldwide. Environmental and food contamination is an issue constantly discussed. In the present study, the melamine content in milk samples with three package types was measured by HPLC/UV. Melamine is not a lipophilic compound. Therefore, the selected samples were low-fat milk. The melamine content in various packaged milk, including packet, polyethylene bags, and plastic packaging, is 790 ± 39.8, 50.7 ± 13, and 57.7 ± 24.54ppb, respectively. According to the existing standards, the measured values in all the milk samples were lower than the permitted limits. The risk assessment for adults and children showed that the HQ value for both age groups was less than 1. Therefore, milk consumption will not pose a health risk in terms of contamination with melamine.

A gradient micromechanical model to explore flexoelectric copolymers via stochastic chain growth

Flexoelectric sensors respond with an electric polarization when they are subjected to inhomogeneous deformation. When these are based on polymeric materials, the electro-mechanical coupling relates to the loss of microstructural symmetries of the polar polymer chains. The object of this work is to explore the mechanisms that induce flexoelectricity in soft (co)polymers via a micromechanical model that explicitly considers the spatial composition distribution of polymer chains. To this end, we analyze the deformation of the Arruda–Boyce 8-chain cell under inhomogeneous deformation and its influence on the overall polarization resulting from the polar monomers. Cells with random-walk chains and tailored degree of entanglement feed Monte Carlo simulations to inform an effective chain dipole that drives the flexoelectric polarization. Homogeneous stretch/compression of the cell accompanying bending deformation reinforce the flexoelectric response. In addition, we focus on stochastic chain-growth processes and the insertion of different types of polar monomers within a same chain. Here, we introduce a model where reactivity ratios of real copolymerization reactions control the resulting flexoelectric coupling. Since the framework allows to relate the effective flexoelectric polarization to any structural isomer distribution, it is especially convenient to model copolymers. Overall, the model is proposed as a versatile framework to explore the intricacies of flexoelectric (co)polymers and to foster the design of flexoelectric devices from real manufacturing parameters.

Functional Chitosan: Recent Gamma Radiation Chemistry of Organic Derivatives

Abstract: This Special Issue will cover the recent radiation chemistry of chitosan (CS) and the attempts that researchers have made to prepare a plethora of derivatives for diverse synthetic applications. The cutting-edge science carried out by experts regarding the gamma-radiation-induced synthesis methods, types of monomers used for grafting the CS, and enhanced properties of the new organic compounds are provided here.

Electropolymerization of D-A type monomers consisting of mono-triphenylamine moiety for electrochromic devices and supercapacitors

Redox active conjugated polymers have been received great research interest due to their potential applications in electrochromic devices and supercapacitors. In this work, three donor-acceptor (D-A) monomers (TPA-BY, TPAP-BY, TPAT-BY) consisting of single triphenylamine unit were synthesized and further deposited on ITO glass via electrochemical polymerization for electrochromic devices and supercapacitors. The obtained polymer films (PTPA-BY, PTPAP-BY, PTPAT-BY) exhibited reversible redox behavior and obvious color change upon voltage variation, especially the optical contrast of PTAP-BY reaching up to 81% at 720 nm. Moreover, the present novel conjugated polymers showed supercapacitor performance with areal specific capacitance among 2.2 ∼ 3.9 mF·cm−2 at a current density of 0.06 mA·cm−2, guaranteeing their potential application in energy saving smart windows.

Evolution of lignin pyrolysis heavy components through the study of representative lignin monomers

Seven typical lignin monomers with different number of methoxyl groups and different 4-substituted patterns were pyrolyzed at 500 °C and 700 °C for 120 s to simulate the secondary polymerization and side chain conversion reactions of primary pyrolytic lignin monomers. The pyrolytic heavy oil components were identified at molecular scale with Fourier transform-ion cyclotron resonance mass spectrometry (FT-ICR-MS) and analyzed with Kendrick mass defect (KMD) and van Krevelen diagrams. The detected heavy components were typically phenolic oligomers formed dominantly through the radical coupling reactions of phenol radicals (C6H4O) and methoxyl radicals (OCH2). Model compounds with CC type 4-substituted groups were prone to produce more phenolic oligomers with more aromatic units. For the CO type model compounds, the number of methoxyl groups have significant influence on the generation of heavy components, thereby affecting the char yields. Rising temperature promotes the generation of heavy components through three main routes, namely the additions of CH2, OCH2 and C6H4O. These routes were mapped on van Krevelen diagrams, shedding light on the evolution patterns of both polymerization and side chain conversion reactions during the secondary pyrolysis of lignin.

A tough and strain-stiffening ionogel enabled by moderate microphase separation for epidermal multi-sensor

Stretchable ionogels demonstrate promising potentials in the next-generation epidermal electronics, due to their high conductivity, non-volatility and thermal stability. Nevertheless, the typical plasticization of ionic liquids (ILs) renders it challenging to achieve high toughness with skin-like strain-stiffening feature. Here we introduce moderate microphase separation structure by randomly polymerizing two types of monomers with different compatibility with ILs to obtain an ionogel with two-phase structure (continuous phase and microphase). The homogenous continuous phase endows the ionogel with high stretchability (over 1000% strain) via the reversible breakage of ion-dipole and dipole-dipole interactions, while the moderate microphase can strengthen the ionogel at large deformation. These two phases cooperate to realize a high toughness (5.26 MJ/m3) with strain-stiffening feature (“S” shaped stress-strain curve). Moreover, this ionogel also shows brilliant ant-swelling capability in multiple solvents, self-healing capability and high sensitivity to strain and temperature, inspiring us to explore the application as epidermal multi-sensor for human motions detection, air velocity recognition and physiological signal monitoring in aquatic environments.

The effect of branched versus linear side chain on thieno[3,4-c]pyrrole-4,6-dione-based donor-acceptor-donor type monomers and their p- and n-dopable polymers

The conjugated backbone has been the focus of the most research, while the structure of the side chains has received less attention. Here, we focus on making new donor–acceptor–donor (D–A–D) type conjugated monomers by bearing a thieno[3,4-c]pyrrole-4,6-dione (TPD) with octyl chain at the imide nitrogen as the acceptor unit and 3,4-ethylenedioxythiophene (EDOT), and 3,3-didecyl-3,4-dihydro-2H-thieno[3,4-b][1,4]dioxepine (ProDOT) as the donor units and their corresponding polymers. The optical and electrochemical properties of octyl substituted monomers and their corresponding polymers were compared with their ethylhexyl counterparts. Changing the alkyl side chain on the TPD unit from linear to branched has no effect on onset potential, optical band gap (Eg), perceived color, electrochromic contrast, or switching time. Nonetheless, donor strength has significant impact on the properties of monomers and their corresponding polymers. EDOT-bearing monomers and polymers have lower onset and oxidation potentials, Eg values than their ProDOT counterparts due to more electron donating ability of ethylenedioxy bridge in comparison to the propylenedioxy bridge. Octyl substituted monomers, P-Octyl and E-Octyl, demonstrated high sensitivity towards the Fe3+ ion, making them viable candidates for use in ion sensing, and their corresponding polymers, PE-Octyl and PP-Octyl, are both p- and n-dopable, which is a desirable property for conjugated polymers. Furthermore, PP-Octyl was found to be soluble in common solvents, and PP-Octyl in toluene can be oxidized with antimony pentachloride (SbCl5).

Biobased Copolymers via Cationic Ring-Opening Copolymerization of Levoglucosan Derivatives and ε-Caprolactone.

Simultaneous ring-opening copolymerization is a powerful strategy for the synthesis of highly functional copolymers from different types of cyclic monomers. Although copolymers are essential to the plastics industry, environmental concerns associated with current fossil-fuel-based synthetic polymers have led to an increasing interest in the use of renewable feedstock for polymer synthesis. Herein, we report a scalable synthetic platform to afford unique polysaccharides with different pendant functional groups from biomass-derived levoglucosan and ε-caprolactone via cationic ring-opening copolymerization (cROCOP). Biocompatible and recyclable bismuth triflate was identified as the optimal catalyst for cROCOP of levoglucosan. Copolymers from tribenzyl levoglucosan and ε-caprolactone, as well as from tribenzyl and triallyl levoglucosan, were successfully synthesized. The tribenzyl levoglucosan monomer composition ranged from 16% to 64% in the copolymers with ε-caprolactone and 22% to 79% in the copolymers with triallyl levoglucosan. The allylic levoglucosan copolymer can be utilized as a renewably derived scaffold to modify copolymer properties and create other polymer architectures via postpolymerization modification. Monomer reactivity ratios were determined to investigate the copolymer microstructure, indicating that levoglucosan-based copolymers have a gradient architecture. Additionally, we demonstrated that the copolymer glass transition temperature (Tg, ranging from -44.3 to 33.8 °C), thermal stability, and crystallization behavior could be tuned based on the copolymer composition. Overall, this work underscores the utility of levoglucosan as a bioderived feedstock for the development of functional sugar-based copolymers with applications ranging from sustainable materials to biomaterials.

Release of Monomers from Dental Composite Materials into Saliva and the Possibility of Reducing the Toxic Risk for the Patient.

Background and Objectives: The objective of this study was (1) to measure the amount of monomers released into the saliva depending on the time elapsed after the hardening of the composite and on the type of monomer used; and (2) with the prolongation of the light-curing procedure, to publish information on whether it would be possible to influence the level of leached monomers. Materials and Methods: HPLC technique was used to monitor the levels of the unpolymerized monomers Bis-GMA, Bis/EMA, TEGDMA, and UDMA from the four commonly used composite materials, released into the saliva of a volunteer with intact dentition. The levels were monitored in 3 time periods during 24 h after composite hardening. From every composite material, 4 samples were formed and cured with an LED lamp for 10 s, 20 s, 40 s, and 60 s. After the light curing, the same polishing procedure was used and the samples were leached in blank saliva samples. Results: We observed that every monitored composite material eluted monomers into the saliva after its application. The amount of monomers depended on the time elapsed after the curing of the composite and on the type of composite used. A 40 s LED curing procedure can reduce the amount of leached monomers in comparison with the standard 20 s procedure, especially for monomers of higher molecular weight. Conclusions: Our study confirmed the hypothesis that the release of monomers gradually decreases with increasing time after the hardening of the composite filling.

Application of HSAB Theory in the Selective Reduction of Quinoline

Comprehensive SummaryIt is very important to develop efficient synthetic strategies for site‐specific functionalization of tetrahydroquinolines due to their indispensable roles in pharmaceutical and agrochemical industries. We apply hard/soft acid/base (HSAB) theory to selective reduction of quinoline and achieve a series of C3‐functionalized tetrahydroquinoline in high to excellent yields (up to 99%) under mild conditions with the catalysis of B(C6F5)3. A series of in situ NMR reactions are also performed to investigate this cascade reaction. Moreover, AB type monomer 6‐(dimethylsilyl) quinoline and AA/BB type monomer 6,6'‐biquinoline are synthesized for polymer synthesis, which represents the first example of silicon bridged polytetrahydroquinoline.

Self‐Limited Hyperbranching Polymerization of Di‐N‐Phenoxycarbonyl N‐Substituted Diglycines

AbstractHyperbranched poly(α‐amino acid)s have caught great attention due to their excellent biocompatibility, biodegradability, and bioactivity. However, hyperbranched polypeptoids are rarely reported because of the challenge of synthesis. Herein, unique polymerizations of N,N'‐diphenoxycarbonyl‐N,N'‐(1,4‐phenylenebismethylene)–diglycine (di‐NNPC, an A*B*‐A*B*‐type monomer) which uncommonly result in hyperbranched polypeptoids rather than gels after the complete consumption of di‐NNPC are reported. The molecular weights of the hyperbranched polypeptoids are controlled by the degree of branching via tuning the initial concentrations of monomer and basic catalyst. N‐Phenyloxycarbonyl glycine pendant groups plentifully remained on the polymer chains are used for Gd3+ complexation and post‐modification, which makes the hyperbranched polypeptoids multifunctional single molecular micelles applicable as magnetic resonance imaging contrast agents and photoluminescence probes.

Effect of Monomer Type on the Synthesis and Properties of Poly(Ethylene Furanoate).

This work aimed to produce bio-based poly(ethylene furanoate) (PEF) with a high molecular weight using 2,5-furan dicarboxylic acid (FDCA) or its derivative dimethyl 2,5-furan dicarboxylate (DMFD), targeting food packaging applications. The effect of monomer type, molar ratios, catalyst, polycondensation time, and temperature on synthesized samples' intrinsic viscosities and color intensity was evaluated. It was found that FDCA is more effective than DMFD in producing PEF with higher molecular weight. A sum of complementary techniques was employed to study the structure-properties relationships of the prepared PEF samples, both in amorphous and semicrystalline states. The amorphous samples exhibited an increase in glass transition temperature of 82-87 °C, and annealed samples displayed a decrease in crystallinity with increasing intrinsic viscosity, as analyzed by differential scanning calorimetry and X-ray diffraction. Dielectric spectroscopy showed moderate local and segmental dynamics and high ionic conductivity for the 2,5-FDCA-based samples. The spherulite size and nuclei density of samples improved with increased melt crystallization and viscosity, respectively. The hydrophilicity and oxygen permeability of the samples were reduced with increased rigidity and molecular weight. The nanoindentation test showed that the hardness and elastic modulus of amorphous and annealed samples is higher at low viscosities due to high intermolecular interactions and degree of crystallinity.

Wheat Pore-Forming Toxin-Like Protein Confers Broad-Spectrum Resistance to Fungal Pathogens in Arabidopsis.

Fusarium head blight (FHB), caused by the hemibiotrophic fungus Fusarium graminearum, is one of the major threats to global wheat productivity. A wheat pore-forming toxin-like (PFT) protein was previously reported to underlie Fhb1, the most widely used quantitative trait locus in FHB breeding programs worldwide. In the present work, wheat PFT was ectopically expressed in the model dicot plant Arabidopsis. Heterologous expression of wheat PFT in Arabidopsis provided a broad-spectrum quantitative resistance to fungal pathogens including F. graminearum, Colletotrichum higginsianum, Sclerotinia sclerotiorum, and Botrytis cinerea. However, there was no resistance to bacterial or oomycete pathogens Pseudomonas syringae and Phytophthora capsici, respectively in the transgenic Arabidopsis plants. To explore the reason for the resistance response to, exclusively, the fungal pathogens, purified PFT protein was hybridized to a glycan microarray having 300 different types of carbohydrate monomers and oligomers. It was found that PFT specifically hybridized with chitin monomer, N-acetyl glucosamine (GlcNAc), which is present in fungal cell walls but not in bacteria or oomycete species. This exclusive recognition of chitin may be responsible for the specificity of PFT-mediated resistance to fungal pathogens. Transfer of the atypical quantitative resistance of wheat PFT to a dicot system highlights its potential utility in designing broad-spectrum resistance in diverse host plants. [Formula: see text] Copyright © 2023 The Author(s). This is an open access article distributed under the CC BY-NC-ND 4.0 International license.

Boosting biogas production from recalcitrant lignin-based feedstock by adding lignin-derived carbonaceous materials within the anaerobic digestion process

Lignocellulosic biomass can add to the worldwide resource of biogas; however, the aromatic structure of lignin is recalcitrant which impairs biodegradation. Direct interspecies electron transfer (DIET) may overcome limitations in the biodegradation of lignin derivatives. Within a circular bioeconomy system, lignin-derived biochar and activated carbon were assessed for their ability to enhance the digestion of a typical lignin monomer – syringaldehyde. Biochar at 5–10 g/L significantly reduced the lag-phase time by 33–42% possibly due to the enhancement of syntrophic hydrogenotrophic methanogenesis. In comparison, activated carbon at 1–10 g/L reduced the lag-phase time by 46–85% and significantly accelerated the degradation of volatile fatty acids, due to a combinational effect of enhanced syntrophic oxidation and DIET. When activated carbon was added at a higher dosage of 20 g/L, the highest biomethane yield (426.6 ml/g) was achieved; an increase of 33% compared to the digestion of syringaldehyde alone. The enhancement was ascribed to the metabolic shift from the hydrogenotrophic to the DIET pathway, which could be implied from the microbial community dominated by Methanosaeta. The superior function of activated carbon over biochar was speculated to be associated with its larger surface area and higher abundance of the CO group.