Internal Cross-linking Research Articles

Droplet microfluidics for double lipase immobilisation using TiO2 and alginate microbeads

A double immobilisation technique was developed for C. antarctica lipase (CALB) that improved its enzymatic activity and solved difficulties frequently observed in reactions catalysed by lipases. The first immobilisation consisted of CALB adsorption onto a TiO2 nanoparticle surface (CALB TiO2). The adsorption was carried out by an oriented monolayer formed by CALB’s hydrophilic amino acids and the TiO2 surface, leaving the CALB’s active site accessible for reaction. As a result, an increase in enzymatic activity was achieved. The Relative Enzymatic Activity ((REA) obtained was 289%. The second immobilisation consisted of CALBTiO2 entrapment into calcium alginate microbeads [(CALBTiO2)EDTA-Ca], obtained by an internal crosslinking ion-exchange mechanism and using microfluidic droplet technique. The microbiocatalyst obtained, (CALBTiO2)EDTA-Ca, retained a high enzymatic activity (REAt=0 = 232%) and stability (REAt=30days = 263%) at a size (diameter, Ø=8.9·104 nm) that enabled easier recovery than CALBTiO2 (Ø = 2.3·102 nm) or CALBFree (Ø=5.0 nm), and showed a favourable porosity for diffusion without releasing CALBTiO2. Although the microbeads showed CALBFree leaching, as demonstrated by the loss of REA after a mechanical resistant test, (CALBTiO2)EDTA-Ca maintained an almost constant REA.

A template synthesized strategy on bentonite-doped lignin hydrogel spheres for organic dyes removal

A super-adsorbent bentonite-doped lignin hydrogel spheres (LHS-BT) were synthesized in 2 min via a simple template method to remove cationic dyes in wastewater. In this process, acrylic acid (AA) and 2-acrylamido-2-methyl-propanesulfonic acid (AMPS) are grafted onto lignosulfonate through free radical reaction to construct polymer cross-linking network and enhance the adsorption capacity of lignin. Moreover, polyethersulfone was designed as a template to protect the internal crosslinking and maintain the spherical shape. Then, the template shell was ingeniously removed through heat shrinkage. The shell separation and drying process was completed in one step, reducing the post-processing process. A series of characterization methods were used to evaluate the structural characteristics of LHS-BT. The influences of dye concentration, initial pH value, temperature and contact time on adsorption procedure were systematically studied. The adsorption kinetics and equilibrium adsorption isotherms are in accordance with the pseudo-second-order kinetic model and Langmuir isotherm model, respectively. Adsorption experiments showed that LHS-BT have ultra-high adsorption capacity (2541.76 mg/g for malachite green, 1284.46 mg/g for methylene blue and 1047.72 mg/g for rhodamine B) and faster adsorption rate within 85 min. Additionally, LHS-BT exhibited excellent recyclability without significant efficiency loss for at least five cycles. The mechanism of dyes molecular capture onto LHS-BT might be principally ascribed to electrostatic attraction, π-π interaction and hydrogen bonding. Thus, LHS-BT exhibits great potential for used in efficient, environmental, and economical wastewater remediation. Lastly, it is proved that LHS-BT is suitable for adsorption column to quickly purify wastewater containing dyes.

Biophysical Considerations in the Rational Design and Cellular Targeting of Flexible Polymeric Nanoparticles.

How nanoparticle (NP) mechanical properties impact multivalent ligand-receptor-mediated binding to cell surfaces, the avidity, propensity for internalization, and effects due to crowding remains unknown or unquantified. Through computational analyses, the effects of NP composition from soft, deformable NPs to rigid spheres, effect of tethers, the crowding of NPs at the membrane surface, and the cell membrane properties such as cytoskeletal interactions are addressed. Analyses of binding mechanisms of three distinct NPs that differ in type and rigidity (core-corona flexible NP, rigid NP, and rigid-tethered NP) but are otherwise similar in size and ligand surface density are reported; moreover, for the case of flexible NP, NP stiffness is tuned by varying the internal crosslinking density. Biophysical modeling of NP binding to membranes together with thermodynamic analysis powered by free energy calculations is employed, and it is shown that efficient cellular targeting and uptake of NP functionalized with targeting ligand molecules can be shaped by factors including NP flexibility and crowding, receptor-ligand binding avidity, state of the membrane cytoskeleton, and curvature inducing proteins. Rational design principles that confer tension, membrane excess area, and cytoskeletal sensing properties to the NP which can be exploited for cell-specific targeting of NP are uncovered.

Study on Performance Optimization and Physical Properties Testing of a New Type of High Thermal Conductive Damping Coating

Surface coating of damping paint is a common method to suppress structural vibration and reduce noise, but damping paint has poor thermal conductivity which limits it’ s application to transformers, reactors and other equipment that have high requirements for heat dissipation. In this paper, a new type of high thermal conductivity damping coating is prepared by emulsion polymerization, among which, a polyurethane emulsion with internal cross-linking structure and an acrylic emulsion with polymerization function are used as main agents, mica powder is used as the main damping function filler. By adjusting the proportion of non-metallic thermal conductive filler Al2O3 and thermal conductive fiber to explore the influence of different thermal conductive fillers on the thermal conductivity and damping performance of the damping coating. The paint is applied to aluminum and iron plates, and the sound insulation capacity is tested to study the influence of paint thickness, fiber addition, fiber type, viscoelasticity, and temperature aging on the sound insulation performance of damping sound insulation panels. The test results show that by adding thermally conductive filler Al2O3 and thermally conductive fibers, a thermally conductive network chain is formed inside the damping coating, which greatly improves the thermal conductivity of the coating while ensuring the damping performance and the effect of vibration and noise reduction.

Intrinsic anti-corrosion, self-healing and mechanical resistance behaviors of epoxy composite coating intercalated with novel mixed Ni(II), Pd(II), and Cd(II) complex cross-linking accelerators for steel petroleum tanks

Multi-functional protective epoxy coatings were applied to display synergistic resistance properties on the steel/coating interfacial zone of petroleum storage tanks (PST). This work investigated the synthesis of new mixed Ni(II), Pd(II), and Cd(II) complexes of metformin (MF) and 2,2/bipyridine (Bipy) as internal cross-linking accelerators for steel epoxy coatings. The ligands and their complexes were identified by CHN analysis, molar conductance, magnetic tendency, TGA/DTG, FT-IR, 1H NMR, and UV–Visible analysis. FT-IR results underlined that MF and Bipy were chelated with metal ions as bidentate ligands through two imines (–CNH) groups of MF and via two nitrogen of pyridine rings for Bipy. Polyamine cured epoxy coating formulations loaded with the same concentration of MF, Bipy, and mixed complexes were prepared. The corrosion inhibiting demeanor evaluated by the salt spray corrosion trial demonstrated that the minimum corrosion rate (CR) was calculated at 0.00028 mm/y. It also exhibited a superior protection efficiency (PE) of 99.90% for EPO/MC-Ni coating with an outstanding self-healing performance. AFM microstructure survey affirmed the smoothest and harder epoxy composite matrix of EPO/MC-Ni coating without the appearance of protuberances over the coating surface. EIS measurements were carried out using oil wells formation water aggressive medium to affirm the protective mechanism offered by the checked coatings. The electrochemical results displayed that EPO/MC-Ni coating exhibited the best resistance values (Rct = 995 and Rp = 945 kΩ cm2) and achieved the highest protection efficiency at 97.23%. Mechanical efforts on the modified Ni(II) coating layer emphasized the best adhesion pull-off evaluation at 6.7 MPa and impacted resistance of 67.3 J.

Preparation and Characterization of Glucose and Sulfamate Double‐Modified Biodegradable Waterborne Polyurethane

AbstractA kind of glucose and sulfamate double‐modified waterborne polyurethane (WPU) was synthesized by using glucose (GLC) and N‐[(2‐amionoethyl)‐amino] ethane sulphonated sodium (AAS) as internal crosslinking agent, polycaprolactone glycol (PCL) as soft segment, 2,2‐bis(hydroxymethyl) propionic acid (DMPA) and N‐[(2‐amionoethyl)‐amino] ethane sulphonated sodium (AAS) as hydrophilic monomers. The influences of AAS and GLC content on the WPU structure and properties were analyzed and characterized by high speed of centrifugation, particle size examination, ATR‐FTIR, TEM, DMA, TGA, SEM, tensile tests, contact angle, water uptake and degradation measurements. The test results indicated that the modified biodegradable WPU had great comprehensive properties. Compared with the unmodified polyurethane, the prepared cross‐linked WPU had a good stability (over 6 months), outstanding mechanical strength (51.55 MPa for WPU4 films) and biodegradability (the weight loss in soil and PBS/lipase reached 25.2 % and 11.8 % for 6 weeks), which made them appropriate supplements for the traditional waterborne polyurethanes in the future.

Dynamic Processes and Mechanisms Involved in Relaxations of Single-Chain Nano-Particle Melts.

We present a combined study by quasielastic neutron scattering (QENS), dielectric and mechanical spectroscopy, calorimetry and wide-angle X-ray diffraction on single-chain nano-particles (SCNPs), using the corresponding linear precursor chains as reference, to elucidate the impact of internal bonds involving bulky cross-links on the properties of polymer melts. Internal cross-links do not appreciably alter local properties and fast dynamics. This is the case of the average inter-molecular distances, the β-relaxation and the extent of the atomic displacements at timescales faster than some picoseconds. Contrarily, the α-relaxation is slowed down with respect to the linear precursor, as detected by DSC, dielectric spectroscopy and QENS. QENS has also resolved broader response functions and stronger deviations from Gaussian behavior in the SCNPs melt, hinting at additional heterogeneities. The rheological properties are also clearly affected by internal cross-links. We discuss these results together with those previously reported on the deuterated counterpart samples and on SCNPs obtained through a different synthesis route to discern the effect of the nature of the cross-links on the modification of the diverse properties of the melts.

Suppression of hydrolytic degradation in labile polymer networks via integrated styrenic nanogels

ObjectiveThe objective of this study was to demonstrate an approach with potential to increase the life of dental restorative polymers in water, by maintaining their strength and toughness with varied content of inert or reactive styrenic pre-polymeric additives. It was hypothesized that addition of styrene-co-divinylbenzene nanogels to a conventional dimethacrylate resin (e.g. TEGDMA) would reduce its susceptibility towards hydrolytic degradation, while maintaining equivalent mechanical properties. MethodsPolymerization kinetics and functional group conversions were determined by Fourier transform infrared spectroscopy. Triple-detection gel permeation chromatography was used for nanogel particle characterization. A goniometer was used to measure water contact angle on experimental and control photocured polymers. Hydrolytic degradation and mass loss evaluation was performed after extended water storage of an intentionally hydrolytically degradable polymer. Resin viscosity was determined rheometrically and polymer mechanical properties were evaluated using three-point flexural testing with TEGDMA-nanogel formulations. ResultsThe polymer network with highest level of nanogel loading (50 wt%) and the highest level of internal nanogel crosslinking (50 mol%) had the lowest degree of equilibrium swelling ratio and mass loss. The flexural modulus and ultimate strength of polymerized TEGDMA and styrenic nanogel-modified TEGDMA were not statistically different (p > 0.05). SignificanceDue to improved shielding throughout the bulk of methacrylate-based polymers, including an example with an intentionally hydrolytically labile network structure, and a dramatic decrease of water uptake while maintaining equivalent mechanical properties, styrenic nanogel additives especially in high loading levels provide an excellent alternative to eliminate the adverse effects of water and presumably salivary fluids.

Hydration and Thermal Response Kinetics of a Cross-Linked Thermoresponsive Copolymer Film on a Hydrophobic PAN Substrate Coating Probed by In Situ Neutron Reflectivity.

The hydration and thermal response kinetics of the cross-linked thermoresponsive copolymer poly((diethylene glycol monomethyl ether methacrylate)-co-poly(ethylene glycol) methyl ether methacrylate), abbreviated as P(MEO2MA-co-OEGMA300), thin film on a hydrophobic polyacrylonitrile (PAN) substrate coating, which resembles a synthetic fabric, is probed by in situ neutron reflectivity (NR). The PAN and monomer (MEO2MA and OEGMA300) solutions are sequentially spin-coated onto a silicon (Si) substrate. Afterward, plasma treatment is applied to realize the cross-linking of PAN and monomers. The as-prepared cross-linked P(MEO2MA-co-OEGMA300) film on the hydrophobic PAN substrate coating presents a two-layer structure: a substrate-near layer, which is a mixture of PAN and P(MEO2MA-co-OEGMA300), and a main layer, which is composed of pure hydrophilic P(MEO2MA-co-OEGMA300). During hydration in D2O vapor atmosphere, the hydrophobic PAN component prevents the formation of D2O enrichment in the substrate-near layer. However, an additional vapor-near layer is observed on top of the main layer, which is enriched with D2O. The hydration process is constrained by the cross-linking points in the film, inducing the relaxation time to be longer than that in a spin-coated P(MEO2MA-co-OEGMA300) film. Because the as-prepared cross-linked film presents a transition temperature (TT) at 38 °C, the hydrated film switches to the collapsed state when the temperature is increased from 23 to 50 °C. The response to a thermal stimulus is also slower due to the existence of the internal cross-linking points as compared to the spin-coated film. Interestingly, no reswelling is observed at the end of the thermal stimulus, which can be also attributed to the presence of internal cross-linking points.

Improving freeze–thaw stability of soy protein isolate-glucosamine emulsion by transglutaminase glycosylation

This paper studies the improvement of freeze–thaw stability of emulsions by incorporating glucosamine into soy protein isolate (SPI) by using transglutaminase. The occurrence of enzymatic glycosylated SPI reaction is confirmed by SDS-PAGE. Through the measurement of creaming index and oiling off, we find that both soy protein isolate-enzymatic without glucosamine (SPI-E) and glycosylated SPI by transglutaminase (SPI-G) can effectively improve the freeze–thaw stability of emulsions. The analysis of particle size, degree of flocculation and coalescence indicates that macromolecular aggregates were formed because transglutaminase enzyme promoted glycosylation and also promoted the cross-linking of protein and protein or the internal cross-linking of protein. Therefore, the particle size of the SPI-G emulsion before freezing and thawing is larger than that of the SPI emulsion. After freeze–thaw cycles, it can be seen that although the particle size of SPI-G is increasing, it is significantly smaller than that of SPI emulsion after freeze–thaw. According to the optical microscope, it can be seen that the SPI emulsion has obvious aggregation of oil droplets after freeze–thawing, and SPI-G effectively improves oil droplet aggregation.

Characterization of a TNFR2-Selective Agonistic TNF-α Mutant and Its Derivatives as an Optimal Regulatory T Cell Expander.

Regulatory T cells (Tregs) are a subpopulation of lymphocytes that play a role in suppressing and regulating immune responses. Recently, it was suggested that controlling the functions and activities of Tregs might be applicable to the treatment of human diseases such as autoimmune diseases, organ transplant rejection, and graft-versus-host disease. TNF receptor type 2 (TNFR2) is a target molecule that modulates Treg functions. In this study, we investigated the role of TNFR2 signaling in the differentiation and activation of mouse Tregs. We previously reported the generation of a TNFR2-selective agonist TNF mutant, termed R2agoTNF, by using our unique cytokine modification method based on phage display. R2agoTNF activates cell signaling via mouse TNFR2. In this study, we evaluated the efficacy of R2agoTNF for the proliferation and activation of Tregs in mice. R2agoTNF expanded and activated mouse CD4+CD25+ Tregs ex vivo. The structural optimization of R2agoTNF by internal cross-linking or IgG-Fc fusion selectively and effectively enhanced Treg expansion in vivo. Furthermore, the IgG-Fc fusion protein suppressed skin-contact hypersensitivity reactions in mice. TNFR2 agonists are expected to be new Treg expanders.

Effect of polymer chains entanglements, crosslinks and finite extensibility on the nonlinear dynamic oscillations of dielectric viscoelastomer actuators

Soft materials exhibiting large deformation under external stimuli have gained an increasing attention in the recent past because of their potential applications in soft transducers aimed at achieving biomimetic actuation. This paper theoretically analyzes the effect of internal properties, including entanglements, crosslinks and finite extensibility of polymer chains along with inherent viscoelastic properties of polymers on the performance of Dielectric Elastomer actuator (DEA) in dynamic modes of actuation. A physics based nonaffine material model proposed by Davidson and Goulbourne is used to model the polymer chains entanglements, crosslinks and finite extensibility. To incorprate the viscoelastic properties, a rheological material model based on the additive decomposition of the isotropic strain energy density into equilibrium and viscous parts is implemented. A computationally efficient method, which relies on the principle of least action is used for extracting the governing equation representing the dynamic motion of the DE actuator. The results demonstrate that DEAs with strong entanglements and crosslinks along with small finite extensibility of polymer chains exhibits lower deformation level in DC dynamic modes of actuation. It is inferred that the strong entanglements and crosslinks in polymer chains enhances the resonant frequency, but debilitate the intensity of vibration of viscoelastic DEAs. Further, the periodicity and stability of the nonlinear oscillations exhibited by the viscoelastic DEAs are assessed by employing the Poincare maps and phase portraits. The results of the present investigation can be applied effectively in bridging the mechanism between the microcosmic polymer chains and macroscopic dynamic behavior of viscoelastic DE actuators.

Assessing the Angiogenic Efficacy of Pleiotrophin Released from Injectable Heparin-Alginate Gels.

With this work, we design alginate-based hydrogels for therapeutically directing revascularization and repair processes in vivo. We immobilize pleiotrophin (PTN) in injectable hydrogel formulations as the target factor to stimulate proangiogenic responses in endothelial cells. The optimized heparin-alginate/chitosan hydrogels, produced by internal crosslinking with calcium carbonate, show good biocompatibility and injectability and allow controlling the release of immobilized proteins in the subcutaneous tissue over a period of 7 days. In vitro assays, performed with translational human induced pluripotent stem cell-derived endothelial cells, and the in vivo Matrigel plug assay are conducted to demonstrate the angiogenic effects of PTN on endothelial cells. Our results indicate that PTN stimulates endothelial cell morphogenesis in vitro and the migration of endothelial cells and macrophages as soon as 4 days after injections of the developed hydrogels, promoting the formation of structures similar to the healthy granulation tissue, which is an indicator of healing in ischemic wounds. These studies provide the rationale for further investigating this novel therapeutic for pursuing increased vascular density for efficient regeneration of ischemic tissues, by leveraging the host endothelial cell population to initiate angiogenic and reparative processes in vivo. Impact statement Localized, sustained, and controlled delivery of angiogenic factors is crucial for enabling the formation of novel vascular networks in ischemic tissues. This study describes the development of an injectable heparin-alginate/collagen hydrogel for controlling the in vivo release and bioactivity of pleiotrophin (PTN), a heparin-binding factor with significant angiogenic activity. We demonstrate that PTN promotes angiogenesis in an in vitro model of hypoxia and in preclinical subcutaneous models. These results advance our understanding of PTN function in guiding therapeutic angiogenesis and are critical to inform the development of novel translational strategies for ischemic tissue repair and regeneration.

Superabsorbent polymer with improved permeability and absorption rate using hollow glass microspheres

AbstractItaconic acid‐vinyl sulfonic acid based super absorbent polymer (SAP) was synthesized by aqueous solution polymerization using ammonium persulfate as the initiator, tetra (ethylene glycol) diacrylate as the internal crosslinking agent, and sodium hydroxide as the neutralizing agent. Surface‐crosslinking was introduced to improve the low absorbency under load of the itaconic acid‐based SAP. Hollow glass microspheres were added during surface‐crosslinking to improve the absorption properties and permeability of the SAP. Hollow glass microspheres increased the specific surface area of SAP and acted as an incompressible filler resulting in the improvement of gel strength and the relief of gel blocking by preventing adhesion between SAP particles. The surface‐crosslinked SAP with 2 wt% hollow glass microspheres showed the highest permeability and absorbency under load. The absorption rate of the synthesized material was also increased.

Effect of crosslinked structure on the chemical degradation of EPDM rubber in an acidic environment

The degradation of peroxide-cured EPDM and sulfur-cured EPDM in an acid solution (12.5 ppm H2SO4+1.8 ppm HF) was investigated, and it was found that the degradation of the two in an acid solution was different. The degradation degree of the sulfur curing system is lower than that of the peroxide curing system. During the aging process, the molecular main chain of the peroxide-cured EPDM was broken, resulting in a double bond and C=O structure. When there is a coagent TAIC in the peroxide curing system, the presence of TAIC delays the degradation time of the EPDM molecular backbone, and the hydrolysis reaction of the TAIC crosslinking point occurs preferentially, which makes the stability of EPDM improved. In addition, regardless of the presence or absence of TAIC, the peroxide-cured EPDM undergoes a crosslinking reaction in the later stage of aging, resulting in an ether-crosslinked structure, thereby improving the damaged crosslinking network. Unlike the degradation of the peroxide curing system, the breakage of the molecular backbone does not occur in the sulfur-cured EPDM, but only an internal crosslinking reaction of the curing precursor occurs, resulting in a crosslinked network dominated by polysulfide bonds, thereby increasing the crosslinking density of the EPDM during the aging process.

Cotton Fibers/PVA Based Neutral Hydrogel with Internal Cross-Linking as Electrolyte for High Performance Supercapacitors

Cotton Fibers/PVA Based Neutral Hydrogel with Internal Cross-Linking as Electrolyte for High Performance Supercapacitors

Light Scattering and Rheological Studies of 3D/4D Printable Shape Memory Gels Based on Poly (N,N-Dimethylacrylamide-co-Stearyl Acrylate and/or Lauryl Acrylates).

In this work, we present the structural analysis of 3D/4D printable N,N-dimethylacrylamide (DMAAm)-co-stearyl acrylate (SA) and/or lauryl acrylate (LA)-based shape memory gels (SMGs). We characterized these gels by scanning microscopic light scattering technique (SMILS) where a time- and space-averaged correlation function is obtained to overcome the inhomogeneous media. Thus, the characteristic size of the gel internal network (mesh size, ξ) and crosslinking densities are estimated from the Einstein–Stokes formula. The rheological study of the SMGs revealed information about their mechanical strength and transition temperature. From the experimental storage modulus measured by rheological study, crosslinking density and mesh size of the network were also calculated. Both the techniques suggest that SMG with high crystalline content of SA monomer in the gel network contain smaller mesh size (1.13 nm for SMILS and 9.5 nm for rheology study) and high crosslinking density. The comparative study between the light scattering technique and rheological analysis through the quantitative analysis of crosslinking densities will be important to understand the structural properties of the SMGs.

Collective Motions and Mechanical Response of a Bulk of Single-Chain Nano-Particles Synthesized by Click-Chemistry.

We investigate the effect of intra-molecular cross-links on the properties of polymer bulks. To do this, we apply a combination of thermal, rheological, diffraction, and neutron spin echo experiments covering the inter-molecular as well as the intermediate length scales to melts of single-chain nano-particles (SCNPs) obtained through ‘click’ chemistry. The comparison with the results obtained in a bulk of the corresponding linear precursor chains (prior to intra-molecular reaction) and in a bulk of SCNPs obtained through azide photodecomposition process shows that internal cross-links do not influence the average inter-molecular distances in the melt, but have a profound impact at intermediate length scales. This manifests in the structure, through the emergence of heterogeneities at nanometric scale, and also in the dynamics, leading to a more complex relaxation behavior including processes that allow relaxation of the internal domains. The influence of the nature of the internal bonds is reflected in the structural relaxation that is slowed down if bulky cross-linking agents are used. We also found that any residual amount of cross-links is critical for the rheological behavior, which can vary from an almost entanglement-free polymer bulk to a gel. The presence of such inter-molecular cross-links additionally hinders the decay of density fluctuations at intermediate length scales.

Tuning the Electrical and Solar Thermal Heating Efficiencies of Nanocarbon Aerogels

Nanocarbon aerogels display outstanding electrical and solar thermal heating efficiencies. However, little is known about the relationship between their microstructure and the heating performance. In this study, two different types of carbon nanotube (CNT) aerogels were synthesized via an ice-templating (IT) and emulsion-templating (ET) approach, respectively, which induces a drastic difference in internal microstructures, cross-linking densities, and porosities. These structural differences give rise to substantial efficiency differences in electrical aerogel heating (e.g., 46 °C/W for rET-CNT aerogel, 75 °C/W for rIT-CNT aerogel). Systematic comparison of nanocarbon aerogel microstructure in terms of nanocarbon type, envelope density, and nanocarbon graphiticity shows that the Joule-heating efficiency is highly correlated with the thermal conductivities of the aerogels, where aerogels with lower thermal conductivities exhibit higher Joule-heating efficiencies. This relationship is also observed for solar thermal aerogel heating, with the aerogels of lowest thermal conductivity (rIT-CNT aerogel) exhibiting a 30% higher efficiency in solar water evaporation, compared to rET-CNT aerogels. These results demonstrate that the heating properties of nanocarbon aerogels can be readily tuned and enhanced through structural control alone. The findings provide a new perspective for the design of nanocarbon aerogels for applications that involve electrical or solar thermal heating, such as temperature-dependent separation, sorption, sensing, and catalysis.

Preparation of itaconic acid bio-based cross-linkers for hydrogels

Itaconic acid (IA) is a bio-based unsaturated monomer, which has been limitedly used in free-radical polymerization due to low reactivity of its carbon-carbon double bond and lack of tendency toward homo-polymerization. In the present work, IA was modified with glyceryl methacrylate (GMA) or epichlorohydrin (ECH) to synthesize two new IA-based materials, i.e., IA-GMA and IA-ECH, respectively. After the characterization of the crosslinkers by 1H NMR and FTIR, IA-GMA containing two methacrylate groups in the structure was used as an internal crosslinker for the preparation of a superabsorbent polymer (SAP). The obtained IA-GMA crosslinked SAP showed a high water absorbency under load (AUL) up to 23.9 g/g compared to commercial SAPs (14–18 g/g), so it can be a potential crosslinker for SAP preparation without a requirement of the surface treatment process as a time and energy-consuming process. Moreover, the application of IA-ECH, possessing hydroxyl or epoxy functionalities as an internal and surface crosslinker in the synthesis of SAPs was investigated. The unique ion structure of IA-ECH as an external crosslinker resulted in improvement in gel strength, as well as AUL up to 30.7 g/g. The SAPs crosslinked by IA-ECH as internal crosslinker presented a high water absorbency (Qw) and saline absorbency (Qs).