Acrylate Units Research Articles

Telechelic Dithiol Copolymers as Tunable Building Blocks for Synthesizing Multiblock Materials

ABSTRACTA new strategy is reported to access α,ω‐dithiol polymer building blocks with tunable molecular weights and compositions for the preparation of random multiblock copolymers based on styrenic, acrylic, and siloxane repeat units. This facile synthetic approach provides access to dithiols through a two‐step process: (1) an initial copolymerization of vinyl monomers with ethyl lipoate followed by (2) disulfide bond reduction, producing dithiol terminated polymer products. Thiol‐terminated polymers are easily prepared over a wide range of molecular weights (2–32 kDa) by simply controlling the feed ratio of vinyl monomer to ethyl lipoate. Mixtures of these linear dithiol‐terminated building blocks were repolymerized via oxidative coupling to create random multiblock copolymers with high molecular weights (68–95 kDa) and controlled degradability. In summary, this approach for preparing and recombining telechelic dithiol polymers creates opportunities to manipulate the mechanical and physical properties of multiblock copolymers using a synthetically simple and versatile platform.

Fluorophilic Sigma(σ)‐Lock Self‐Healable Copolymers

AbstractAlthough F‐Containing molecules and macromolecules are often used in molecular biology to increase the binding with Lewis acidic groups by introducing favorable C−F dipoles, there is virtually no experimental evidence and limited understanding of the nature of these interactions, especially their role in synthetic polymeric materials. These studies elucidate the molecular origin of inter‐ and intra‐Chain interactions responsible for self‐healing of F‐Containing copolymers composed of pentafluorostyrene and n‐butyl acrylate units (p(PFS/nBA). Guided by dynamic surface oscillating force (SOF) and spectroscopic measurements supported by molecular dynamics (MD) simulations, these studies show that the reformation of σ‐σ orbitals in −C−F of PFS and CH3CH2− of nBA units enables the recovery of entropic energy via fluorophilic‐σ‐lock van der Waals forces when PFS/nBA molar ratios are ~50/50. The strength of these interactions determined experimentally for self‐healable PFS/nBA compositions is in the order ~0.3 kcal/mol which primarily comes from fluorophilic‐σ‐lock (~70 %) contributions. These interactions are significantly diminished for non‐self‐healable counterparts. Strongly polarized −C−F σ orbitals create lateral dipolar forces enhancing the affinity towards −C−H orbitals, facilitating energetically favorable interactions. Entropic recovery driven by non‐Covalent bonding offers a valuable tool in designing materials with unique functionalities, particularly self‐healable batteries and energy storage devices.

Fluorophilic Sigma(σ)-Lock Self-Healable Copolymers.

Although F-Containing molecules and macromolecules are often used in molecular biology to increase the binding with Lewis acidic groups by introducing favorable C-F dipoles, there is virtually no experimental evidence and limited understanding of the nature of these interactions, especially their role in synthetic polymeric materials. These studies elucidate the molecular origin of inter- and intra-Chain interactions responsible for self-healing of F-Containing copolymers composed of pentafluorostyrene and n-butyl acrylate units (p(PFS/nBA). Guided by dynamic surface oscillating force (SOF) and spectroscopic measurements supported by molecular dynamics (MD) simulations, these studies show that the reformation of σ-σ orbitals in -C-F of PFS and CH3CH2- of nBA units enables the recovery of entropic energy via fluorophilic-σ-lock van der Waals forces when PFS/nBA molar ratios are ~50/50. The strength of these interactions determined experimentally for self-healable PFS/nBA compositions is in the order ~0.3 kcal/mol which primarily comes from fluorophilic-σ-lock (~70 %) contributions. These interactions are significantly diminished for non-self-healable counterparts. Strongly polarized -C-F σ orbitals create lateral dipolar forces enhancing the affinity towards -C-H orbitals, facilitating energetically favorable interactions. Entropic recovery driven by non-Covalent bonding offers a valuable tool in designing materials with unique functionalities, particularly self-healable batteries and energy storage devices.

Acrylic acid and vinylamine copolymers: Anomalous acidity and association with short polyacids

Acrylic acid and vinylamine copolymers represent one of the simplest polyampholyte structures. The acid-base and solution properties of these copolymers are hardly studied, and there are no works devoted to the synthesis of a set of copolymers with different compositions. We have synthesized a set of acrylic acid and vinylamine copolymers containing from 21 to 95 mol% acrylic acid units. The copolymers show the hydrodynamic properties and solubility of typical polyampholytes. Potentiometric titration revealed unusual acid-base properties of the new copolymers. The addition of HCl to the copolymers in the form of sodium/potassium salt results in only partial protonation of carboxyl anions and amine groups, including the acidic range (pH 2.5). This abnormally high acidity of acrylic acid and vinylamine copolymers is probably due to the formation of strong intra- and intermolecular hydrogen or ionic bonds between partially protonated and protonated groups: ∼COO−+H3N∼, COOH∙∙∙:NH2∼, ∼H2N:∙∙∙ +H3N∼. Poly(vinylamine) and copolymers are able to stabilize curcumin in aqueous medium, significantly increasing its concentration in the neutral pH range. Polymers with high content of amine groups prevent curcumin degradation, probably by converting it to a more stable anionic form. New copolymers are promising substances for the creation of nucleic acid carriers for gene therapy and genetic engineering. The copolymer containing 21 % acrylic acid is comparable to poly(vinylamine) in terms of interaction with oligonucleotides, but yields more homogeneous polyplexes without the impurity of positively charged and potentially toxic particles.

Amphiphilic pH-responsive ABC triblock copolymers via RAFT-mediated aqueous PISA and comparison with their A-b-(B-co-C) diblock copolymer counterparts

The influence of the macroRAFT agent architecture on the morphology of the self-assemblies obtained by aqueous RAFT dispersion polymerization in PISA is studied by comparing amphiphilic AC, A(B-co-C) diblocks and ABC triblock copolymers, constituted of N,N-dimethylacrylamide (DMAm = A), acrylic acid (AA = B) and N-cyanomethylacrylamide (CMAm = C) monomer units. The aim of this study is to better understand the impact of the presence of pH-sensitive acrylic acid units and their spatial distribution in block copolymers. Generally, the presence of a fully protonated intermediate block of PAA between the two blocks (based on PDMAm and PCMAm) favors the formation of higher-order morphologies. These ABC triblock copolymers assemblies are pH-responsive and can undergo morphological transitions through the controlled deprotonation or protonation of the PAA segment, but do not completely dissociate at high pH (i.e. when AA units are fully ionized) unlike their A(B-co-C) diblock counterparts, where the pH-responsive monomer unit is homogeneously distributed within the solvophobic block.

Mechano-responsive chameleon-gel integrated with dumbbell-shaped spiropyran cross-linker

Stimuli-responsive hydrogels are being extensively studied altering their structures and physiochemical properties in response to external changes. However, technologies to visualize the internal stress of a gel generated by swelling and deswelling are still lacking. Here, we present a dumbbell-shaped spiropyran cross-linker synthesized by top-down grafting with poly(ethylene glycol) (PEG) acrylates. The cross-linker consists of spiropyran core that exhibits optical changes in response to mechanical stress, hydrophilic 2-arm PEGs that allow the cross-linker soluble in an aqueous solution, and acrylate units at each end of PEGs that cross-links the gel. As a result, the chameleon-gels integrated with the dumbbell-shaped spiropyrans were proved to visualize the internal stress generated by swelling and deswelling in a controlled manner. Overall, this new strategy to prepare the mechano-responsive hydrogel would be actively used in sensing, imaging, and display for drug delivery, tissue engineering, and environmental engineering, etc.

Effect of pH on the incorporation of acrylic acid units in the core of polymer nanoparticles prepared by PISA and on their morphology

The molar fraction and ionization of acrylic acid (αAA) in the monomer feed affect the chemical composition, the composition profile and the particle morphology in PISA.

The influence of dibutyl sebacate on the sorption properties of a composite superabsorbent based on chitosan

Composite superabsorbents, combining both acrylate and biodegradable units, are more environmentally friendly products compared to fully synthetic analogues, however, their equilibrium degree of swelling Qe, usually, lower than the latter. Therefore, the search for new approaches to increase this parameter is an urgent task of modern chemistry. A promising way to solve this problem seems to be the use of plasticizers - low-molecular compounds that increase the segmental and molecular mobility of macromolecules. The purpose of this study was investigation of the effect of the presence of dibutyl sebacate on the sorption properties of composite superabsorbents containing chitosan. Dibutyl sebacate is known as a plasticizer for many industrially important polymers, including cellulose derivatives, and is also less toxic than commonly used phthalates. Superabsorbents based on acrylic acid and acrylamide containing 10 wt.% chitosan with different molecular weights: 20, 200, and 600 kDa were obtained by radical precipitation polymerization with substance initiation. The structure of the resulting superabsorbents was confirmed by FTIR spectroscopy, and the morphology of their surfaces was studied by scanning electron microscopy. With an increase in the molecular weight of the polysaccharide used, a decrease in the equilibrium degree of swelling of the resulting composite superabsorbent in distilled water was observed. In the case of swelling in a 0.15 M NaCl solution, a sharp decrease in Qe values occurred. The presence of dibutyl sebacate increased the equilibrium degree of swelling in distilled water of superabsorbents obtained based on chitosan with molecular weights of 200 and 600 kDa. The increase in Qe values correlated with the molecular weight of the polysaccharide: the higher it was, the more pronounced was the effect of the presence of dibutyl sebacate. A study of the swelling kinetics of superabsorbents showed that, regardless of the presence of dibutyl sebacate, the process is two-stage: a stage of fast and slow water sorption was observed. Using mathematical kinetic models, it was shown that swelling was controlled by chemisorption, and at the slow stage of swelling, the diffusion of water molecules inside the superabsorbent phase played a significant role. Thus, the use of dibutyl sebacate is a promising approach to increasing the equilibrium degree of swelling of composite superabsorbents based on chitosan with a molecular weight of more than 200 kDa.

A rhodamine-based fluorescent probe for specific recognition of mitochondrial cysteine

Cysteine (Cys) is of great significance in biological systems and in the process of mitochondrial function. Highly selective and specificity recognizable probes for mitochondrial Cys are still in demand. In this work, a new fluorescent probe for detecting mitochondrial Cys was developed based on a rhodamine derivative. In this probe, acrylate unit was selected as group of Cys recognition and quaternized pyridinium moiety was utilized as mitochondrial targeting group. The probe showed colorless in daylight and extremely weak fluorescence in 365 nm due to its spirolactone structure when Cys did not exist. In the presence of Cys, the probe exhibited orange in daylight and produced intensely green fluorescence in 365 nm owing to the formation of the conjugated xanthene structure. The probe exhibited specific recognition for Cys. There was an excellent linear relationship between fluorescence intensity at 540 nm of the probe and the Cys concentration from 4.0 × 10-8 to 1.0 × 10-5 mol⋅L-1. And the detection limit was estimated to be 1.57 × 10-8 mol/L. Moreover, the probe was almost non-cytotoxic, possessed targeting-mitochondria ability and could sense Cys at the cellular level. The good bioimaging ability makes the probe a potential tool for studying mitochondrial Cys in biological samples.

Concerted flexible and steric strategy in α-diimine nickel and palladium mediated insertion (Co-)Polymerization

To address the issues of poor thermostability of catalyst and low polymer molecular weight resulted from chain transfer at high temperature in olefin polymerization, versatile strategies have been utilized in the benchmark α-diimine nickel and palladium catalysts. In this contribution, a concerted flexible and steric strategy was highlighted in the α-diimine nickel and palladium catalysts. Compared to the seminal Brookhart catalyst, these newly generated nickel catalysts exhibited improved thermostability over a wide range of temperature from 30 °C to 130 °C, showed higher catalytic activities, and produced significantly higher (4.7–5.8 times) molecular weight polymers in ethylene polymerization, which are highly branched polyethylenes (76–110/1000C, SR = 72 %). Notably, high molecular weight polyethylene (up to 219 kg mol−1) was even afforded at 130 °C, which is extremely challenging when the flexible substituent is used in α-diimine system. The corresponding palladium analogues by using the same strategy further produced high molecular weight ethylene-methyl acrylate copolymers (up to 137 kg mol−1) at the difficult 70 °C in the copolymerization of ethylene and methyl acrylate. The incorporation of methyl acrylate could be tuned (0.6–2.9 mol%), where methyl acrylate units distribute both in the main chain and at the end of branches (15 %:85 %).

Quantitative analysis of acrylic acid in acrylic pressure-sensitive adhesives by reactive pyrolysis-GC/MS using N,O-bis(trimethylsilyl)trifluoroacetamide as a trimethylsilylation reagent with two-step heating

Acrylic pressure-sensitive adhesives (APSAs) have been used in a variety of fields and the composition of their monomers is a very important factor in determining their physical properties. Monomers containing polar functional groups, such as acrylic acid (AA), are often used as raw materials for APSAs, and the number of these monomer units in the polymer chain has a significant effect on the adhesive properties. However, due to its high reactivity and polarity, it is not easy to accurately quantify AA in APSAs by conventional reactive pyrolysis gas chromatography mass spectrometry (Py-GC/MS). In this study, quantitative analysis of AA in APSAs was examined by reactive Py-GC/MS using N,O-bis(trimethylsilyl)trifluoroacetamide (BSTFA) as a trimethylsilylation (TMS) reagent (Py (BSTFA)-GC/MS). First, the APSA sample was mixed with BSTFA and heated at 60 ºC for 30 min to accelerate TMS derivatization of any unpolymerized AA monomers (AA-TMS). If unreacted BSTFA remains after derivatization, it will react with AAs produced by the pyrolysis of acrylic ester units. These additional AA monomers,will results in the over-estimation of the true amount of unpolymerized AA monomers. To prevent this undesirable effect by residual reagent, the TMS-derivatized sample was further heated at 100 ºC for 10 min before pyrolysis in order to remove residual BSTFA and solvent. The derivatized sample was measured by Py-GC/MS at 600 ºC and the relative standard deviation of the peak area ratio of AA-TMS derived from unpolymerized AA monomers to the internal standard (anthracene-d10) was less than 5% (n = 5). In the calibration curves made for four APSA samples with known compositions, good linearity was obtained for the raw materials of butyl acrylate and 2-ethylhexyl acrylate in addition to AA-TMS. Quantitative analysis of AA monomers in a commercial APSA sample showed fairly good agreement with the amount of AA determined by the official method of analysis using the acid-base titration (JIS K 5601–2–1). The results obtained in this study indicate that Py (BSTFA)-GC/MS is effective for the compositional analysis of APSAs.

Effect of a Hydrophobic Branching Agent in Physically Cross‐Linked Hydrogels with Shape‐Memory and Self‐healing Abilities

AbstractPhysically crosslinked hydrogels consisting of polyacrylamide (Aam) and polyoctadecylacrylate (C18A) blocks, leading to hydrophilic and hydrophobic domains respectively, are prepared by micellar polymerization. A multifunctional monomer (divinylbenzene, DVB), is also employed to create branched chains. The effect of the polymer composition and the amount of the branching agent on the material characteristics are evaluated. The melting enthalpies of the hydrophobic domains increase as the n‐octadecyl acrylate unit amount increases and, in a parallel fashion, an increase in the mechanical modulus G' of the hydrogel is observed. Furthermore, G′ increases as the DVB concentration increases. Self‐healing behavior is also demonstrated both visually and by rheological measurements. Finally, once heated above the melting temperature (Tm), these hydrogels can be deformed into different shapes that can be fixed on cooling. Then, heating again above Tm, the original shape is recovered thus indicating shape memory characteristics.

Transparent Cross-Flow Platform as Chemiluminescence Detection Cell in Cross Injection Analysis.

This work presents the use of a transparent 'Cross Injection Analysis' (CIA) platform as a flow system for chemiluminescence (CL) measurements. The CL-CIA flow device incorporates introduction channels for samples and reagents, and the reaction and detection channels are in one acrylic unit. A photomultiplier tube placed above the reaction channel detects the emitted luminescence. The system was applied to the analysis of (i) Co(II) via the Co(II)-catalyzed H2O2-luminol reaction and (ii) paracetamol via its inhibitory effect on the catalytic activity of Fe(CN)63- on the H2O2-luminol reaction. A linear calibration was obtained for Co(II) in the range of 0.002 to 0.025 mg L-1 Co(II) (r2 = 0.9977) for the determination of Co(II) in water samples. The linear calibration obtained for the paracetamol was 10 to 200 mg L-1 (r2 = 0.9906) for the determination of pharmaceutical products. The sample throughput was 60 samples h-1. The precision was ≤4.2% RSD. The consumption of the samples and reagents was ca. 170 µL per analysis cycle.

3D Printing of Customized Drug Delivery Systems with Controlled Architecture via Reversible Addition‐Fragmentation Chain Transfer Polymerization

3D printing via reversible addition‐fragmentation chain transfer (RAFT) polymerization has been recently developed to expand the scope of 3D printing technologies. A potentially high‐impact but relatively unexplored opportunity that can be provided by RAFT‐mediated 3D printing is a pathway toward personalized medicine through manufacturing bespoke drug delivery systems (DDSs). Herein, 3D printing of drug‐eluting systems with precise geometry, size, drug dosage, and release duration/profiles is reported. This is achieved through engineering a range of 3D models with precise interconnected channel‐pore structure and geometric proportions in architectural patterns. Notably, the application of the RAFT process is crucial in manufacturing materials with highly resolved macroscale features by confining curing to exposure precincts. This approach also allows spatiotemporal control of the drug loading and compositions within different layers of the scaffolds. The ratio between the polyethylene glycol units and the acrylate units in the crosslinkers is found to be a critical factor, with a higher ratio increasing swelling capacity, and thus enhancing the drug release profile, from the drug‐eluting systems. This proof‐of‐concept research demonstrates that RAFT‐mediated 3D printing enables the production of personalized drug delivery materials, providing a pathway to replace the “one‐size‐fits‐all” approach in traditional health care.

Adhesion of Polymer to TiO2 Particles Decreases Photocatalytic Activity of Polyelectrolyte Hydrogel Photocatalyst

AbstractA comparative study on the photocatalytic activity was done for TiO2/poly(acrylamide‐co‐potassium acrylate) composite hydrogels with varying content of potassium acrylate monomer units. The presence of the acrylate units led to the increase in the swelling ratio of hydrogel and to the enhancement of the diffusion of the methyl orange probe dye to the surface of the embedded TiO2 particles. However, the photocatalytic activity was not improved. Microcalorimetry data showed that while the enthalpy of polymer adhesion to the TiO2 particles surface was positive in the case of polyacrylamide and it became negative if acrylate units were included in the polymer network. Likely, the adhesion enhancement occurred due to the electrostatic interaction among acrylate monomer units and surface of TiO2 particles. As a result of polymer adhesion to the active surface of the catalyst particles was partly blocked and the photocatalytic activity of the composite hydrogel diminished.

Fast UV-Curable Zwitter-Wettable Coatings with Reliable Antifogging/Frost-Resisting Performances.

Antifogging surfaces with unique properties to migrate severe fog formation have gained extensive interest, which is of particular interest for transparent substrates to obtain high visibility and transparency. To date, a large number of strategies including superhydrophilic or superhydrophobic surfaces and titanium dioxide (TiO2)-based composite coatings have been developed based on different mechanisms. Although these surfaces exhibit effective antifogging properties, the rigid nanostructures, cumbersome preparation, and the need for UV light excitation largely limit their widespread applications. Herein, we report a zwitter-wettable antifogging and frost-resisting coating through a fast UV-curable cross-linking of copolymer with benzophenone groups. A series of random copolymers consisting of hydrophilic hydroxyethyl methacrylate (HEA), hydrophobic methyl methacrylate (MMA), and benzophenone-based acrylate units are developed by thermally triggered free-radical polymerization. Upon UV light irradiation, a highly efficient antifogging/frost-resisting coating is covalently bonded on a polycarbonate plate surface, maintaining a light transmission higher than 85%, which was confirmed in both high and low temperature anti-fog tests. Moreover, the wetting behaviors reveal that the antifogging performance exhibited by the zwitter-wettable surface mainly relies on its surface water-adsorbing capability to imbibe condensed water vapor on the surface outmost layer. Notably, the antifogging/frost-resisting behaviors can be well regulated by adjusting the hydrophilic/hydrophobic units, due to the proper balance between the water-adsorption and coating stability. Owing to its simplicity, low-cost preparation and high efficiency, this UV-curable acrylate antifogging coating may find a wide range of applications in various display devices in analytical and detection instruments.

Methacrylate Polymers With "Flipped External" Ester Groups: A Review.

Current resin composites have favorable handling and upon polymerization initial physical properties that allow for efficient material replacement of removed carious tooth structure. Dental resin composites have long term durability limitations due to the hydrolysis of ester bonds within the methacrylate based polymer matrix. This article outlines the importance of ester bonds positioned internal to the carbon-carbon double bond in current methacrylate monomers. Water and promiscuous salivary/bacterial esterase activity can initiate ester bond hydrolysis that can sever the polymer backbone throughout the material. Recent studies have custom synthesized, with the latest advances in modern organic chemical synthesis, a novel molecule named ethylene glycol bis (ethyl methacrylate) (EGEMA). EGEMA was designed to retain the reactive acrylate units. Upon intermolecular polymerization of vinyl groups, EGEMA ester groups are positioned outside the backbone of the polymer chain. This review highlights investigation into the degradation resistance of EGEMA using buffer, esterase, and microbial storage assays. Material samples of EGEMA had superior final physical and mechanical properties than traditional ethylene glycol dimethacrylate (EGDMA) in all degradation assays. Integrating bioinformatics-based biodegradation predictions to the experimental results of storage media analyzed by LC/GC-MS revealed that hydrolysis of EGEMA generated small amounts of ethanol while preserving the strength bearing polymer backbone. Prior studies support investigation into additional custom synthesized methacrylate polymers with "flipped external" ester groups. The long term goal is to improve clinical durability compared to current methacrylates while retaining inherent advantages of acrylic based chemistry, which may ease implementation of these novel methacrylates into clinical practice.

Uncommon Polyketides from Penicillium steckii AS-324, a Marine Endozoic Fungus Isolated from Deep-Sea Coral in the Magellan Seamount

Four unusual steckwaic acids E–H (1–4), possessing a rarely described acrylic acid unit at C-4 (1–3) or a double bond between C-12 and C-13 (4) are reported for the first time, along with four new analogues (5–8) and two known congeners (9 and 10). They were purified from the organic extract of Penicillium steckii AS-324, an endozoic fungus obtained from a deep-sea coral Acanthogorgiidae sp., which was collected from the Magellan Seamount at a depth of 1458 m. Their structures were determined by the interpretation of NMR and mass spectroscopic data. The relative and absolute configurations were determined by NOESY correlations, X-ray crystallographic analysis, and ECD calculations. All compounds were tested for their antimicrobial activities against human- and aquatic-pathogenic bacteria and plant-related pathogenic fungi.

On novel hydrogels based on poly(2-hydroxyethyl acrylate) and polycaprolactone with improved mechanical properties prepared by frontal polymerization

This work aimed to improve the mechanical properties of poly(2-hydroxyethyl acrylate) (PHEA)-based hydrogels by performing their polymerization in the presence of an ad hoc synthesized star-shaped polymer, whose arms are composed of a biopolymer, i.e., polycaprolactone (PCL) end-capped with acrylic units to act as a crosslinker for PHEA. Indeed, this system was designed to have (i) biocompatible, biodegradable, and mechanical strong arms as well as (ii) a star structure with acrylic functionalities to promote the crosslinking of the material. 1H NMR, IR and TGA measurements confirmed the star PCL functionalization, which was carried out starting from a hydroxyl-terminated polymer. Hydrogels were prepared by varying the concentration of the synthesized star polymer, and the properties of the materials obtained by frontal (FP) and bulk polymerization (BP) were compared. Moreover, to evaluate the specific effect of PCL-star-4-2 k-tetraacrylate (PCL-TA) on the crosslinking of the systems, samples were also synthesized using a commercial acrylate crosslinker. For what concerns the frontal polymerization process, fronts were found to be stable in the presence of PCL-TA. The thermal characterization results showed a significant decrease in the PHEA glass transition temperature with increasing PCL-TA content, which was particularly evident in the samples prepared by FP. This result can be attributed to the partial miscibility of the two polymers, which become compatible during the polymerization process by forming a copolymer system. This was confirmed by analyzing the thermal behavior of hydrogels polymerized in the presence of a hydroxyl terminated PCL, i.e., a polymer without active functional end groups. The samples synthesized by FP with the star polymer and the commercial crosslinker, as well as neat PHEA, were subjected to mechanical tests. The mechanical behavior of PCL-based hydrogels was outstanding, exhibiting three time higher modulus than that of crosslinked PHEA, and were structurally stable even under high compression loadings. This remarkable property, combined with the fast and efficient polymerization method and the environmentally friendly properties of PCL, make the developed hydrogels promising systems for practical applications in various fields.

PAAO cryogels from amidoximated P(acrylic acid-co-acrylonitrile) for the adsorption of lead ion

Lead ion is a common heavy metal pollutant and extremely harmful to human health. Therefore, the research about the adsorption and removal of lead ion from sewage and the development of lead ion sorbents keeps greatly significant. In this study, poly(acrylic acid-co-acrylonitrile) (PAAN) cryogels were prepared by cryo-polymerization. After the treatment with hydroxylamine, the amidoximated PAAO cryogels were applied to remove lead ion from lead-contaminated water. The porous structure and high water permeability of the cryogel could fully facilitate the exposure of active sites to efficiently adsorb lead ion. PAAO cryogels showed a high adsorption capacity of 450 mg/g for lead ion. After the first adsorption–desorption cycle, the adsorption capacity of PAAO cryogels regenerated with alkali solution increased to 650 mg/g and remained in the next six cycles. The pseudo-second-order kinetic model and the intraparticle diffusion model fit the adsorption kinetics of lead ion well, indicating its chemi-sorption feature of PAAO cryogel sorbent. The FTIR and XPS studies suggested that carboxyl group of acrylic acid unit as well as the amidoxime group of modified AN unit contributed the enhanced adsorption ability for lead ion.