Simultaneous Crosslinking Research Articles

Fabrication of Zinc(II) Mediated Poly(Acrylamide Co Acrylic Acid) Hydrogel with Thixotropic and Tribological Properties.

Hydrogels have emerged as promising candidates for biomedical applications, such as replacing natural articular cartilage, owing to their unique viscoelastic properties. However, sufficient mechanical properties, self-healing ability, and adhesive nature are some issues limiting its application window. Here, a facile one-pot synthesis of dual cross-linked zinc-coordinated copolymer hydrogels is presented. The network structure of the copolymer hydrogels is strategically developed via dynamic and reversible physical cross-linking by Zn2+ ions and simultaneous covalent cross-linking through a covalent cross-linker viz methylene bisacrylamide. Fourier-transform infrared (FTIR), X-ray diffraction (XRD) scanning electron microscopy (SEM), and Brunauer-Emmett-Teller (BET) analysis have thoroughly characterized the structure of the synthesized hydrogels. The introduction of Zn2+ offers dynamic and reversible complexation, leading to excellent mechanical properties and self-healing features. Moreover, the percentage of the equilibrium water content of zinc-coordinated copolymer hydrogel samples is comparable with that of natural articular cartilage. The Shear sliding study shows the dominant adhesive behavior of HGel-Zn(NO3)2 sample compared to the parent HGel sample. This facile dual cross-linked hydrogel, HGel-Zn(NO3)2, with a combination of good mechanical properties, efficient self-recovery, adequate water content, and favorable adhesive nature, seems very promising to mimic the articular cartilage.

Flexible tactile sensing of magnetic hydrogel composites based on electrical impedance tomography

Flexible and stretchable tactile sensors show promising applications in robotics, prosthetics, and wearable electronics. This paper demonstrates an electrical impedance tomography (EIT) based highly flexible, touch-sensitive pressure sensor using magnetic hydrogels. EIT technology has been explored for continuous distributed strain sensing and tactile imaging. Magnetic hydrogel composites are synthesized by simultaneous polymerization and crosslinking of acrylamide with magnetic carbonyl iron particles (CIPs). The effects of CIPs percentage on morphology, sensitivity, and electrical/mechanical properties is investigated. EIT accurately discerns pressure quantity, shape, and spatial distribution. Lower CIPs volume fractions (3%) exhibit maximum sensitivity to strain fields. Mechanical testing show the hydrogels have excellent fatigue resistance, ideal for repeated compression loading. The results demonstrate the potential of EIT with magnetic hydrogel composites for tactile sensing and imaging, with applications in soft robotics, prosthetics, and wearable electronics. The tunable sensitivity and multifunctionality make these soft composites promising materials for flexible electronics.

3D Printing of Hierarchical Structures Made of Inorganic Silicon-Rich Glass Featuring Self-Forming Nanogratings.

Hierarchical structures are abundant in nature, such as in the superhydrophobic surfaces of lotus leaves and the structural coloration of butterfly wings. They consist of ordered features across multiple size scales, and their advantageous properties have attracted enormous interest in wide-ranging fields including energy storage, nanofluidics, and nanophotonics. Femtosecond lasers, which are capable of inducing various material modifications, have shown promise for manufacturing tailored hierarchical structures. However, existing methods, such as multiphoton lithography and three-dimensional (3D) printing using nanoparticle-filled inks, typically involve polymers and suffer from high process complexity. Here, we demonstrate the 3D printing of hierarchical structures in inorganic silicon-rich glass featuring self-forming nanogratings. This approach takes advantage of our finding that femtosecond laser pulses can induce simultaneous multiphoton cross-linking and self-formation of nanogratings in hydrogen silsesquioxane. The 3D printing process combines the 3D patterning capability of multiphoton lithography and the efficient generation of periodic structures by the self-formation of nanogratings. We 3D-printed micro-supercapacitors with large surface areas and a high areal capacitance of 1 mF/cm2 at an ultrahigh scan rate of 50 V/s, thereby demonstrating the utility of our 3D printing approach for device applications in emerging fields such as energy storage.

Artificially regulated interphase on natural graphite realizes rapid charge and durable high-temperature cycling of Li-ion batteries

Natural graphite (NG) is a strong competitor in the anode market of Li-ion batteries because of its low cost, rich resource, low energy consumption and low carbon dioxide emission during production. The main problems inhibiting its universal application are its high surface area and the attendant unstable solid/electrolyte interphase (SEI), leading to unsatisfactory cycling and rate performance. In this work, a Li+-conductive, thermally and mechanically stable organic polymer layer is successfully constructed on NG surface by virtue of the simultaneous polymerization and crosslinking reactions of chitosan (CS) and acrylic acid (AA). With controllable thickness, the polymer layer denoted as CSAA significantly decreases the specific surface area of NG, works as an inner SEI substrate greatly mitigating the decomposition of electrolyte, and induces the formation of a LiF-rich SEI outer layer. The SEI resistance and activation energy for charge-transfer reactions are considerably reduced. Benefiting from the superior properties of CSAA-derived SEI, the NG@CSAA anodes exhibit a high initial coulombic efficiency of 94.1 %, fast charge/discharge capability and prolonged cycle life at both 25 °C and 45 °C in the LiFePO4 cathodes-based full cells.

β-Cyclodextrin-enabled, densely cross-linked anion-exchange membranes for fuel cell applications

Polyarylpiperidinium anion exchange membranes (AEMs) have been widely studied in anion exchange membrane fuel cells and alkaline electrolyzed water due to their excellent alkali resistance stability. In this work, we report the design and fabrication of poly(p-triphenylene-piperidinyl) (PTP) AEMs quaternized and cross-linked by bromo-β-cyclodextrin (β-CD-Br7). In this type of membranes, the densely cross-linked and quaternized sites derived from β-CD-Br7 can help to construct continuous ion transport channels to facilitate ion conduction. Although the ion exchange capacity (IEC) tended to decrease with increasing cross-linking degree, the qPTP-CD5 membrane with 5 % cross-linking (IEC = 2.3 mmol g−1) produced the most significant microphase separation and the highest conductivity (125.6 mS cm−1 at 80 °C). The membrane also exhibited impressive alkaline stability, with 94.6 % conductivity retention in 1 M NaOH at 80 °C after 1000 h and 90.7 % conductivity retention after 1500 h. Finally, the peak power density of the fuel cell assembled with qPTP-CD5 membranes was 1.216 W cm−2 at 80 °C and there was no significant voltage degradation when operated at 200 mA cm−2 current density for 40 h. This work demonstrates that β-CD can function as a good “platform” for simultaneous cross-linking and quaternization to fabricate high performance AEM.

Empowering PLA Bioplastics: Elevating applications horizon through groundbreaking Eco-Innovative Fibrillation, chain Extension, and crosslinking techniques

This comprehensive study introduces pioneering techniques in the toughening of polylactic acid (PLA) by incorporating thermoplastic polyurethane (TPU) nanofibrils, leveraging two distinct crosslinking methods to significantly enhance the material’s mechanical performance. Method 1 employs a silane/moisture crosslinking process, whereas Method 2 utilizes a tailored diisocyanate crosslinking approach, offering a more environmentally sustainable alternative. Molecular structural analysis was performed extensively by using X-ray photoelectron spectroscopy (XPS), Fourier transform infrared spectroscopy (FTIR), nuclear magnetic resonance (1H NMR), gel permeation chromatography (GPC), rheological assessments, scanning electron microscopy (SEM), and differential scanning calorimetry (DSC). Method 2 not only preserves TPU nanofibrils but also elevates the mechanical properties of PLA-TPU composites beyond the capabilities of Method 1. Notably, by leveraging the simultaneous crosslinking of TPU and chain extension of PLA with the tailored diisocyanate approach, we enhance PLA’s mechanical properties and energy absorption capabilities. These advancements are achieved without a high rubber content, which typically compromises strength/stiffness, thermomechanical stability, crystallization, and transparency of PLA. The resulting composites prepared via Method 2 display remarkable increases in tensile toughness, ranging from 30-60 MPa, and impact strength, achieving a span of 60–140 J/m. This is primarily due to the occurrence of a brittle-to-ductile transition (BDT) at only 3 wt% nanofibril TPU content while maintaining a high PLA modulus of 3 GPa. This critical balance between chain-extending and crosslinking reactions ensures the maintenance of PLA’s inherent strength/stiffness, crystallization, and optical clarity. The research presented here marks a significant shift in the development of tougher, more thermally stable, transparent, and sustainable polymer blends and composites. Method 2, with its tailored fiber size reduction (90–280 nm), and environmental consciousness, broadens the horizon of PLA’s applications.

Amphiphilic Nanoscale Antifog Coatings: Improved Chemical Robustness by Continuous Assembly of Polymers.

Designing effective antifog coatings poses challenges in resisting physical and chemical damage, with persistent susceptibility to decomposition in aggressive environments. As their robustness is dictated by physicochemical structural features, precise control through unique fabrication strategies is crucial. To address this challenge, a novel method for crafting nanoscale antifog films with simultaneous directional growth and cross-linking is presented, utilizing solid-state continuous assembly of polymers via ring-opening metathesis polymerization (ssCAPROMP). A new amphiphilic copolymer (specified as macrocross-linker) is designed by incorporating polydimethylsiloxane, poly(2-(methacryloyloxy)ethyl) trimethylammonium chloride (PMETAC), and polymerizable norbornene (NB) pendant groups, allowing ssCAPROMP to produce antifog films under ambient conditions. This novel approach results in distinctive surface and molecular characteristics. Adjusting water-absorption and nanoscale assembly parameters produced ultra-thin (≤100nm) antifog films with enhanced durability, particularly against strong acidic and alkaline environments, surpassing commercial antifog glasses. Thickness loss analysis against external disturbances further validated the stable surface-tethered chemistries introduced through ssCAPROMP, even with the incorporation of minimal content of cross-linkable NB moieties (5mol%). Additionally, a potential zwitter-wettability mechanism elucidates antifog observations. This work establishes a unique avenue for exploring nanoengineered antifog coatings through facile and robust surface chemistries.

Optimizing skim milk yogurt properties: Combined impact of transglutaminase and protein-glutaminase

The lack of fat in yogurt can lead to alterations in taste and whey separation, reducing consumer acceptance. In this study, the feasibility of enhancing the quality of skim milk yogurt through a combination of transglutaminase (TG) and protein-glutaminase (PG) was investigated. The combination of TG and PG resulted in simultaneous cross-linking and deamidation of CN micelles, with PG deamidation taking priority over TG cross-linking, leading to higher solubility and lower turbidity of milk proteins compared with TG alone. When 0.06 U/mL TG and 0.03 U/mL PG were added, firmness and viscosity indexes significantly increased by 38.26% and 78.59%, respectively, as compared with the control. Microscopic images revealed increased cross-linking with CN and filling of cavities by smaller submicelles in the combination of TG and PG treatment. Furthermore, the combination of TG and PG resolved issues of rough taste and whey separation, leading to improved overall liking. This study highlights the benefits of using both enzymes in dairy production and has important implications for future research.

Fabrication of Triblock Elastomer Foams and Gelation Studies for Oil Spill Remediation.

Polymeric foamed materials are among the most widely utilized technologies for oil spill accidents and releases of oil-contaminated wastewater oil due to their porosity to absorb and separate oil/water effectively. However, a major limitation of traditional polymeric foams is their reliance on an ad/absorption mechanism as the sole method of oil capture, leading to potential oil leakage once their saturation point is exceeded. Tri-block polymer styrene-ethylene-butylene-styrene (SEBS) is a fascinating absorbent material that can bypass this limitation by both capturing oil and providing a sealing mechanism via gelation to prevent oil leakage due to its unique chemical structure. SEBS foams are produced via simultaneous crosslinking and foaming that results in an impressive expansion ratio of up to 15.2 with over 93% porosity. Most importantly, the SEBS foams show great potential as oil absorbents in spill remediation, demonstrating rapid and efficient oil absorption coupled with superhydrophobic properties. Moreover, the unique interaction between the oil and SEBS enables the formation of a physical gel, acting as an effective barrier against oil leakage. These findings indicate the potential for commercializing SEBS foam as a viable option for geotextiles to mitigate oil spill concerns from infrastructures.

Polyethyleneimine crosslinkers: Towards greener crosslinking and simultaneous conditioning of solvent-resistant nanofiltration polyimide membranes?

Crosslinked polyimide is a state-of-the-art membrane material for solvent-resistant nanofiltration (SRNF) and gas separation aiming for applications that involve harsh solvents or plasticizing components in the gas stream, respectively. Preparation of these membranes usually requires a multistep procedure involving hazardous diamine monomers. In this study, two hyperbranched polyethyleneimines (PEIs) with different molecular weights (800 and 25 000 g mol−1) were explored as crosslinking agents in the simultaneous (SIM) crosslinking -procedure where crosslinking takes place during coagulation in the non-solvent bath. Because of their lower volatility compared to traditional diamine crosslinkers, the manipulation of these polymeric forms of crosslinkers is intrinsically less hazardous. It is hypothesized that the conditioning step, a required post-processing step in membrane upscaling to allow subsequent potting, handling, and storage, can be omitted when crosslinking with such polymeric crosslinkers. Results showed how presence of PEI in the non-solvent bath influenced the course of phase inversion, resulting in a range of different membrane morphologies and performances. Drying unfortunately resulted in brittle membranes which lost most of their permeance. Even when residual PEI was allowed to remain in the membrane as a conditioning agent, low dried membrane permeances were obtained. By using PEI or other state-of-the-art crosslinkers prior to drying, light was shed on the structure-performance relationships governing permeance decline when drying SRNF membranes.

Water-Insoluble, Thermostable, Crosslinked Gelatin Matrix for Soft Tissue Implant Development.

In this present study, the material science background of crosslinked gelatin (GEL) was investigated. The aim was to assess the optimal reaction parameters for the production of a water-insoluble crosslinked gelatin matrix suitable for heat sterilization. Matrices were subjected to enzymatic degradation assessments, and their ability to withstand heat sterilization was evaluated. The impact of different crosslinkers on matrix properties was analyzed. It was found that matrices crosslinked with butanediol diglycidyl ether (BDDE) and poly(ethylene glycol) diglycidyl ether (PEGDE) were resistant to enzymatic degradation and heat sterilization. Additionally, at 1 v/v % crosslinker concentration, the crosslinked weight was lower than the starting weight, suggesting simultaneous degradation and crosslinking. The crosslinked weight and swelling ratio were optimal in the case of the matrices that were crosslinked with 3% and 5% v/v BDDE and PEGDE. FTIR analysis confirmed crosslinking, and the reduction of free primary amino groups indicated effective crosslinking even at a 1% v/v crosslinker concentration. Moreover, stress-strain and compression characteristics of the 5% v/v BDDE crosslinked matrix were comparable to native gelatin. Based on material science measurements, the crosslinked matrices may be promising candidates for scaffold development, including properties such as resistance to enzymatic degradation and heat sterilization.

Kinetics of Radiation–Oxidative Aging of HDPE Fibers with Simultaneous Degradation and Crosslinking of Macromolecules

Kinetics of Radiation–Oxidative Aging of HDPE Fibers with Simultaneous Degradation and Crosslinking of Macromolecules

All-aqueous microfluidic printing of multifunctional bioactive microfibers promote whole-stage wound healing

Wound healing involves multi-stages of physiological responses, including hemostasis, inflammation, cell proliferation, and tissue remodeling. Satisfying all demands throughout different stages remains a rarely addressed challenge. Here we introduce an innovative all-aqueous microfluidic printing technique for fabricating multifunctional bioactive microfibers, effectively contributing to all four phases of the healing process. The distinctive feature of the developed microfibers lies in their capacity to be printed in a free-form manner in the aqueous-two phase system (ATPS). This is achieved through interfacial coacervation between alkyl-chitosan and alginate, with enhanced structural integrity facilitated by simultaneous crosslinking with calcium ions and alginate. The all-aqueous printed microfibers exhibit exceptional performance in terms of cell recruitment, blood cell coagulation, and hemostasis. The inclusion of a dodecyl carbon chain and amino groups in alkyl-chitosan imparts remarkable antimicrobial properties by anchoring to bacteria, complemented by potent antibacterial effects of encapsulated silver nanoparticles. Moreover, microfibers can load bioactive drugs like epidermal growth factor (EGF), preserving their activity and enhancing therapeutic effects during cell proliferation and tissue remodeling. With these sequential functions to guide the whole-stage wound healing, this work offers a versatile and robust paradigm for comprehensive wound treatment, holding great potential for optimal healing outcomes.

Effect of Residue Acrylic Monomers in Synthesized Solvent-Free Photoreactive Pressure-Sensitive Adhesives on the Main Properties of Transfer Tapes Applied to Joining Wooden Elements.

This publication describes the influence of residue monomers in synthesized pressure-sensitive adhesives based on acrylics on their main properties-tack, peel adhesion, shear strength and shrinkage-in the form of transfer tapes used for joining wooden elements in the furniture industry. The discussed carrier-free adhesive tapes are synthesized via photo-crosslinking and photopolymerization with UV radiation of the photoreactive prepolymers sandwiched between two adhesive siliconized polyester films. The simultaneous crosslinking and polymerization processes carried out under UV lamps placed simultaneously above and below the crosslinked photoreactive polymer layer lead to the production of a carrier-free adhesive film. The preliminary target of these studies was to investigate how the intensity of UV radiation and the time of its exposure affect the viscosity of the photoreactive compositions and the content of unreacted monomers in them. Next, the influence of the crosslinking agent concentration and UV irradiation time on the content of unreacted monomers after the crosslinking process was tested. The last step of the studies was the investigation of the influence of the residue monomer concentration on the application properties of the obtained pressure-sensitive adhesive layers. The typical PSA application properties were tested on the wood samples: tack, peel adhesion, shear strength (cohesion) and shrinkage.

Enhanced Low-Density Silicone Foams Blown by Water-Hydroxyl Blends.

Water, alcohols, diols, and glycerol are low-cost blowing agents that can be used to create the desired silicone foam structures. Although their combined use can be beneficial, it remains unclear how it affects the physical properties of the resulting materials. We conducted a comparative study of these hydroxyl-bearing blowing agents in fumed silica- and mica-filled polymer composite systems for simultaneous blowing and crosslinking to obtain a low-density, uniform porosity and superior mechanical properties. The foams were optimized for a uniform open-pore structure with densities ranging from 75 to 150 kg‧m-3. Varying the diol chain length (Cn) from one to seven carbons can alter the foam density and structure, thereby enhancing the foam tensile strength while maintaining a low density. Replacing 10 mol% of water with 1,4-butanediol decreased the density by 26%, while increasing the specific strength by 5%. By combining glycerol and water blowing, the resulting foams exhibited a 30% lower apparent density than their water-blown analogs. The results further showed that Cn > 4 alkane chain diols had an odd-even effect on the apparent density and cell wall thickness. All foamable compositions had viscosities of approximately 7000 cSt and curing times below 2 min, allowing for quick dispensing and sufficient time for the foam to cure in semi-industrial volumes.

Simultaneous Physical Cross-Linking and Mechanical Strengthening of Elastomers by Enantiomeric Interactions through Reactive Processing

Simultaneous Physical Cross-Linking and Mechanical Strengthening of Elastomers by Enantiomeric Interactions through Reactive Processing

Fabrication of Porous Heteroatom‐Doped Carbon Networks via Polymer‐Assisted Rapid Thermal Annealing

AbstractPorous carbon materials have increasingly drawn interest for applications ranging from supercapacitive energy storage to bioengineering. However, a simple and scalable fabrication process of such materials, employing low‐cost chemical compounds without sacrificing morphological and chemical control, remains lacking. Here, a novel, rapid, continuous bottom‐up strategy for synthesizing structurally tunable porous carbon network films on insulating and conductive substrates is reported. By employing rapid thermal annealing (RTA) of a commercial polyacrylonitrile‐based blend, simultaneous phase separation and thermal crosslinking are induced, effectively freezing the structure. Subsequent burning of degradable components generates a porous carbon framework ( ≈ 360 to 700 nm) doped with nitrogen and oxygen atoms. Introducing a boron‐containing reagent in the precursor solution enables boron doping and pore size reduction as small as 20 nm, enhancing materials' performance. The direct fabrication of micro‐supercapacitors on stainless steel substrates is demonstrated, achieving an areal capacitance of 12.7 mF cm−2 at 50 mV s−1, with ≈98% retention after 10 000 charge/discharge cycles. The benefit of boron doping is further highlighted for wound healing applications. Because RTA is already an established industrial method, this platform directly facilitates the synthesis of functional porous heteroatom‐doped carbon structures using commercial polymers and dopants for various applications.

Analysis of bio-based acrylate accelerated weathering: A study of nanocellulose impact on the bulk durability of 3D-printed nanocomposites

Bio-based resins for UV-assisted photopolymerization vat 3D printing have received immense research interest. 3D printing has initiated the 4.0 industrial revolution and is expected to squeeze in more production industries, including making materials for outdoor applications. Weathering investigations have been devoted mainly to fossil acrylic polymers. This research aims to close the gap in understanding bio-based acrylic 3D-printed polymer weathering performance. QUV accelerated weathering was used on vegetable oil-based 3D-printed compositions with nanofibrillated cellulose (NFC) as reinforcing filler. Discoloration, cracking, FTIR measurements of surface chemical degradation, and bulk properties evaluated by changes in mechanical performance were used to characterize materials performance during weathering. NFC reinforcement delays the yellowing and cracking during 1000 h of weathering. After weathering, increased flexural stress and strain were achieved with 0.5 wt% NFC loading. Chemical analysis reveals simultaneous photocleavage and additional crosslinking of the macromolecular chains. The glass transition temperature increased by up to 20 °C. NFC introduction in bio-based polymers increased of weathering endurance and mechanical performance. The NFC is compatible with and a perspective filler in bio-based acrylic resins for 3D printing applications.

Silicone-modified polyurea-interpenetrating polymer network fouling release coatings with excellent wear resistance property tailored to regulations

The invasion of alien species via marine organisms attaching to the surfaces of ship hulls is a growing problem. A number of countries have introduced corresponding regulations to combat ship biofouling. One effective way to solve this problem is to apply a fouling release coating with excellent wear resistance. In this study, a silicone-modified polyaspartic ester polyurea was synthesized by a simultaneous crosslinking polymerization. Polyaspartic ester polyurea is employed to form a tightly cross-linked network with excellent toughness and outstanding adhesion, while polydimethylsiloxane is used to form a relatively soft cross-linked network with low surface energy and surface elasticity modulus. Polyurea and silicone molecular chain lock onto each other to form interpenetrating polymer network (IPN) through their respective polymerization systems and cross-linking processes. The synergy between silicone and polyurea provides excellent mechanical properties as well as fouling release performance through the locking mechanism. This study provides a promising and universal strategy for the development of fouling release coatings with excellent wear resistance.

Building Porous Ni(Salen)-Based Catalysts from Waste Styrofoam via Autocatalytic Coupling Chemistry for Heterogeneous Oxidation with Molecular Oxygen.

The development of robust and industrially viable catalysts from plastic waste is of great significance, and the facile construction of high performance heterogeneous catalyst systems for phenol-quinone conversions remains a grand challenge. Herein, a feasible strategy is demonstrated to reclaim Styrofoam into hierarchically porous nickel-salen-loaded hypercrosslinked polystyrene (PS@Ni-salen) catalysts with high activities through an unusual autocatalytic coupling route. The salen is immobilized onto PS chain by Friedel-Crafts alkylation of benzyl chloride derivatives, and the generated hydrogen chloride coordinately promotes the simultaneous crosslinking and bridge formation between aromatic rings via a Scholl coupling route, leading to hierarchically porous networks. After the metallization with Ni, the resultant networks exhibit high catalytic activity for the oxidation of 2,3,6-trimethylphenol to 2,3,5-trimethyl-1,4-benzoquinone under mild conditions (303 K, 1bar of O2 ). This catalyst also demonstrates attractive recycling performance without an obvious loss of catalytic efficiency over five consecutive cycles. This methodology might provide a potential sustainable alternative to construct environmentally benign and cost-effective catalysts for specific organic transformation.