Polymer Network Research Articles

Digitally Programmable Microphase Separation in Polymer Network Generates Microstructure Pattern.

Polymers with microstructure patterns are crucial to many applications, such as separation, optics, electronics, metamaterials, etc. However, introducing microstructure patterns with diverse morphologies and feature sizes ranging from nanometers to micrometers into large-area polymers remains a significant challenge. Here, we design a material system that enables digital programming microphase separation in a polymer network to generate microstructure patterns. The polymer network is engineered to allow digital programming of local modulus, which arrests the length scale of microphase separation to generate various microstructures. These local modulus-regulated microstructures exhibit either bicontinuous or sea-island morphology and have various feature sizes ranging from ∼100 nm to several micrometers. Using household devices of an ink printer and an ultraviolet light lamp, the microstructure patterns can be programmed with fine resolutions (∼100 μm) over large areas (≫100 mm). The locally varied microstructures have different capabilities to scatter light and result in a visible pattern. We further demonstrate this design with a soft anticounterfeiting device. This approach of digital programming microphase separation in polymer networks is applicable to various polymers and provides a platform for designing many other functional devices.

Valence tautomerism, non-innocence, and emergent magnetic phenomena in lanthanide-organic tessellations.

Coordination networks based on lanthanide ions entangle collective magnetic phenomena, otherwise only observed in inorganic 4f materials, and the tunable spatial and electronic structure engineering intrinsic to coordination chemistry. In this review, we discuss the use of 2D-structure-directing linear {LnII/IIII2} nodes to direct the formation of polymeric coordination networks. The equatorial coordination plasticity of {LnII/IIII2} results in broad structural diversity, including previously unobtainable tessellations containing motifs observed in quasicrystalline tilings. The new phases host also magnetic frustration, which is at the origin of enhanced magnetic refrigeration potential. Finally, careful redox matching of Ln node and frontier orbitals of the ligand scaffold has culminated in the discovery of quantitative valence tautomeric conversion in a molecule-based Ln material, opening up new avenues for combining exotic magnetic phenomena with an encoded switch.

Multiscale Elasticity of Epoxy Networks by Rheology and Brillouin Light Spectroscopy.

The response of soft materials to an imposed oscillatory stress is typically frequency dependent, with the most utilized frequency range falling in the range of 10-2-102 rad/s. In contrast to most conventional contact techniques for measuring material elasticity, like tensile or shear rheology and atomic force microscopy, or invasive techniques using probes, such as microrheology, Brillouin light spectroscopy (BLS) offers an optical, noncontact, label-free, submicron resolution and three-dimensional (3D) mapping approach to access the mechanical moduli at GHz frequencies. Currently, the correlation between the experimental viscoelastic (at lower frequencies) and elastic (at higher frequencies) moduli has fundamental and practical relevance, but remains unclear. We utilize a series of solvent-free epoxy polymer networks with variable cross-link density as models to compare the storage modulus, G', (in the MPa range) obtained from shear rheology and the longitudinal modulus, M', (in the GPa range) extracted from BLS. Our results show that G' exhibits a much stronger increase with increasing cross-link density than M' (by a factor of about 3.5). This finding is discussed in the context of the phantom network model for G' and Wood's inverse rule of mixtures for M'. The epoxy polymer network displays an unexpectedly fast hypersonic dispersion compared to its uncross-linked precursor. These results testify the importance of obtaining reliable information about the elasticity of networks and will hopefully trigger further investigations in the direction of bridging the elasticity of soft materials at different scales.

Influence of Biochar and Modified Polyglutamic Acid Co-Coated Urea on Crop Growth and Nitrogen Budget in Rice Fields

Natural superabsorbent polymers (SAPs) were essential coating materials for developing slow-release fertilizers (SRFs) due to low cost and biodegradability. However, conventional natural SAPs were unsuitable for rice systems due to low stability and short slow-release period. Herein, a natural SAP with a semi-interpenetrating polymer network was prepared by poly (γ-glutamic acid) (PGlu), diatomite, and pullulan polysaccharide and combined with biochar to develop double-layer co-coated slow-release urea for rice systems. The results indicated that diatomite and pullulan modification significantly improved the slow-release capacity of SAP, with a significant increase in the average fertilizer 15N content of the soil profile by 37.9 ± 7.4% in 14–56 days. The improved slow-release capacity had significant benefits for the sustainability of the rice system, which increased plant N uptake by 17.2 ± 4.8%, decreased fertilizer N losses by 30.4 ± 7.2%, and increased rice grain yield by 9.88 ± 3.6%. More importantly, this natural SAP was fully degradable and its decomposition products are large amounts of small-molecule nutrients that could provide additional C, N, and Si to rice. Therefore, novel co-coated SRF may emerge as a greatly promising candidate for future intensive paddies.

Constructing robust and antioxidant polyurethane–lignin coatings with biodegradable properties for grass press paper films

The practical applications of grass plastic mulch films are limited because their residues turn into microplastics and enter the food chain. This study solves this problem by preparing a degradable cellulose–lignin–waterborne polyurethane composite grass paper film. First, waterborne polyurethane prepared using a mild method was composited with lignin via an addition reaction and the formation of hydrogen bonding between the –OH groups of lignin and the –NCO and –OH groups of polyurethane. Finally, the as-prepared polyurethane–lignin composite was applied as a coating on the surface of a paper-based material to prepare a grass paper mulch film. The relationship between lignin content and the molecular weight, thermal stability, mechanical properties, polymer network crosslinking density, antioxidant capability, and light transmittance of the coating was studied, revealing that higher lignin contents considerably improved the barrier and mechanical properties of the coating and grass paper mulching film. In particular, a lignin content of 20 % resulted in a grass paper mulching film with outstanding grass pressing performance and degradability. Therefore, the multifunctional, ecofriendly grass paper mulch film prepared from cellulose–lignin–waterborne polyurethane composite materials provides an innovative approach to solve the pollution problem of traditional grass plastic paper mulch.

Linear and Nonlinear Rheological Investigations of Poly(3-hexylthiophene) H-Aggregated Gel Networks.

Owing to its facile synthesis and low cost, poly(3-hexylthiophene) (P3HT) has been extensively investigated in the field of organic electronics. Well-defined packing of P3HT chains and getting controlled morphologies, which solely depend on the polarity of the solvent, remain challenging. Herein, the aggregation behaviors of P3HT in organic solvents having different solvent polarities have been investigated to achieve different orderings of P3HT chains (H-type or J-type). The aggregation in the solution phase and the subsequent structural as well as morphological behaviors of P3HT chains have been investigated by absorption, X-ray powder diffraction, and topological studies, respectively. It has been noticed from absorption studies that P3HT forms H-type aggregates in anisole, phenetole, etc., whereas it produces J-type aggregates in toluene. More surprisingly, H-type aggregations of P3HT chains at low concentrations (CP3HT = 0.001 g/cm3) eventually lead to the formation of the gel network that ceases the flow of the solvents. Contrary to expectations, J-type aggregation in toluene does not produce the gel network at the said concentration. Further, to reveal the viscoelastic and microstructural properties, P3HT gel networks have been thoroughly investigated by small-amplitude oscillatory shear (SAOS) and large-amplitude oscillatory shear (LAOS) with varying concentrations, solvents, and molecular weights of P3HT. With quantitative analysis, the nonlinear rheological characteristics of higher harmonics, strain-stiffening ratio, shear-thinning ratio, dissipation ratio, intracycle transient moduli, and derivative of transient moduli have been evaluated for P3HT networks, which significantly provide the rheological information for the understanding of conducting polymer networks.

Synthesis of sodium alginate grafted and silver nanoparticles filled anionic copolymer polyelectrolytes for adsorption and photocatalytic degradation of a cationic dye from water

Sodium alginate (SA) was grafted to poly (acrylonitrile-co‑sodium acrylate-co-acrylic acid). The grafted copolymer was crosslinked with N. N, methylene bis acrylamide (MBA). Silver nanoparticles (AgNPs) were generated in situ within the growing polymer network by reducing 0.1 mM silver nitrate with 0.05 mM ascorbic acid (ASA). The effect of initiator concentration, total monomer concentration, SA weight%, MBA weight% and acrylonitrile (AN):sodium acrylate (NaAA)/ acrylic acid (AA) molar ratios on the grafting were studied. The nanocomposite was characterized and used for adsorption of methylene blue (MB) dye from water. The composite was also used for photocatalytic degradation of the dye in the presence of sun light. The Box-Behnken design (BBD) of response surface methodology (RSM) with different compositions resulted in an optimized composition of 5:1 M ratio of AN:NaAA/AA, 1 wt% MBA and 2 wt% SA. The nanocomposite (SACP5Ag) prepared with the optimized composition showed an equilibrium batch adsorption(qe, mg/g)/removal(R)% of 245/98 from 50 mg/L MB dye in water and a qe /R% of 18.87/31.4 in a fixed bed adsorption at a feed inlet concentration(mgL−1)/inflow rate (mLmin−1)/bed height (mm) of 100/20/25. The composite showed a photocatalytic degradation efficiency of 98 % in sunlight for 80 min and a 1st order rate constant of 0.02 min−1.

Adhesion properties of thiol-acrylate-epoxy polymer networks based on thiol–epoxy ‘click’ chemistry

This study examined the preparation of epoxy resins with enhanced mechanical strength, modified with thiol-acrylate segments integrated into the polymer network via a thiol–epoxy “click” reaction. Thiol-acrylate-epoxy polymers were synthesized using both single and dual curing processes. In the single curing process, a polythioether (thiol-acrylate) prepolymer was synthesized. The results showed that an epoxy formulation containing 30 wt% of this prepolymer achieved the highest lap shear strength, approximately 57% higher than that of neat epoxy. This improvement indicates strong interactions between the thiol-acrylate segments and the epoxy matrix due to the thiol-epoxy “click” reaction. Dual-cure systems exhibited slightly higher tensile strengths compared to single-cure systems, particularly as the thiol-acrylate segment content increased up to 20%, while also maintaining superior lap shear strengths. Incorporating thiol-acrylate segments raised the tensile strength to 34 MPa, about 25% higher than that of pure epoxy. Polymer networks containing 20–30 wt% of thiol-acrylate segments, in both single and dual-cure systems, demonstrated significant potential as effective adhesive systems. These findings contribute to the development of adhesives with enhanced tensile and lap shear strength, as well as the identification of suitable curing methods.

Environment-tolerant, inherently conductive and self-adhesive gelatin-based supramolecular eutectogel for flexible sensor

Although hydrogels have attracted increasing attention in the stretchable devices, the low adhesion properties and poor environmental adaptation still seriously restrict their development and application. Herein, we focused on the interaction between polymer networks with disperse media and their resultant influence on gel performance, and constructed self-adhesive and environment-tolerant gelatin/polyacrylamide supramolecular-polymer double-network (Gelatin/PAM SP-DN) eutectogels using multiple supramolecular interactions between natural macromolecule and well-designed deep eutectic solvent (DES). The dual networks of Gelatin/PAM SP-DN eutectogels produced significant supramolecular forces with DES, including hydrogen bonding and electrostatic interaction, contributing to enhance the energy dissipation capacity. Additionally, the Gelatin-PAM SP-DN eutectogels were more prone to generate strong bonding force to various substrates, showcasing both in-situ and ex-situ adhesion performance, and even being used for wet and underwater adhesion. The eutectogels revealed excellent environmental tolerance to maintain excellent mechanical flexibility, conductivity and adhesion at high and low temperatures, ensuring the constructed sensor to sensitively and reliably perceive strain, pressure and human motions over a wide temperature range. Also, the eutectogel demonstrated great potential as a temperature sensor. This work opens up a new horizon in the design of multifunctional and environment-tolerant natural macromolecule-based gel materials for flexible electronics, human-machine interaction and health diagnosis.

Preparation of Waterborne Polyurethane Coatings with Enhanced Mechanical Properties and Superhydrophobic Surface

Waterborne polyurethane (WPU) coatings are recognized for their environmental friendliness and non-toxic nature. However, the presence of abundant hydrophilic groups within their polymer networks often restricts their hydrophobicity and mechanical performance. In this study, we utilized two distinct diols to design the molecular structure of WPU, aiming to enhance its mechanical properties by optimizing microphase separation and crystallinity, achieving a tensile strength of 24.13 MPa and a strain of 1350%. The resultant WPU exhibited high cohesion and abundant hydrogen bonding sites, which contributed to its strong adhesion of 8.31 MPa. Moreover, inspired by the self-cleaning function of lotus leaf-micro-nipples, we made the surface superhydrophobic by micro-nano structure. The irregularly embedded structure was formed between the WPU and SiO2@hbp. The surfaces of WPU coatings formed the peak-valley structure similar to the lotus leaf, achieving a water contact angle of 162° and a sliding angle near 1°. Additionally, the self-cleaning property of the coatings was preserved after 200 cycles of friction, each with a single friction distance of 40cm. The environmental friendliness and excellent self-cleaning capabilities of the coating highlight its potential for practical applications and provide a valuable reference for developing waterproof self-cleaning coatings.

Polysulfone-reinforced quorum quenching media with silica cage encapsulation: Advancing biofouling control in anaerobic membrane bioreactors

Microbial quorum quenching (QQ) using live QQ cells entrapped in a hydrophilic polymer network (e.g., hydrogel) reduces membrane biofouling but encounters challenges regarding mechanical robustness and long-term stability. This study addresses this limitation by developing a novel composite biomedia that encapsulates QQ cells (Rhodococcus sp. BH4) within porous silica cages, which act as a protective barrier against solvent exposure, and further reinforces the structure with polysulfone, a thermally and chemically stable polymer. Surface observations confirmed the successful encapsulation of the cells within the silica matrices. Further analyses revealed the distinct nature of the composite media composed of QQ bacteria, silica, and polymer networks with an amorphous structure essential for flexibility and cell viability. The mechanical properties of the polysulfone-reinforced biomedia were significantly improved, with tensile strength nearly four times higher than that of the conventional hydrogel-based biomedia, making it far more durable for long-term applications. When exposed directly to the solvent dimethylacetamide, unprotected BH4 cells experienced severe death and inactivation; however, encapsulation in the porous silica cages maintained 70% cell viability and 77% QQ activity, demonstrating the protective efficacy of the silica matrix. In anaerobic membrane bioreactor applications, the reinforced QQ media showed remarkable biofouling mitigation, extending operational times by approximately threefold and twofold compared to reactors with no media and vacant media, respectively. Using composite QQ media led to significant reductions in the concentrations of biopolymers and quorum-sensing signal molecules, contributing to prolonged membrane service times without negatively impacting overall treatment performance. These findings represent a significant advancement in developing QQ media for antifouling, sustaining the functionality of live QQ cells within durable polymer matrices.

Facile synthesis of Metal-Organic Framework/Chitosan cryogel as a robust Scavenger for Diclofenac sodium

Diclofenac sodium (DS), a commonly detected contaminant in aquatic environments, poses a a significant risk to both the ecological balance and the safety of aquatic products. Therefore, efficient removal of DS from water is ergently needed but remains a major challenge. In this study, an environmentally friendly Fe-based metal–organic framework/chitosan (NH2-MIL-53(Fe)/CS) cryogel was prepared through a Schiff base condensation reaction under mild conditions. Taking advantage of the catalytic role of the MOF in accelerating the reaction between CS and 1,3,5-triformylphloroglucinol, NH2-MIL-53(Fe) powders were incorporated into the polymeric networks within 30 s. Owing to the rich binding sites, the resulting NH2-MIL-53(Fe)/CS cryogel demonstrated remarkable efficacy in eliminating DS from water. The adsorption process reached equilibrium within 120 min with a maximum adsorption capacity of 728.6 mg g−1. A comprehensive mechanistic investigation revealed that the exceptional adsorption capability of the NH2-MIL-53(Fe)/CS cryogel for DS was attributed to the synergistic effect of multiple interactions, including favorable hydrophilicity, electrostatic forces, π-π stacking, hydrogen bonding, and coordination. Thus, this study provides a straightforward and rapid synthesis route for MOF/CS cryogel, offering a promising adsorbent that combines exceptional adsorption performance with ease of separation. The resulting MOF/CS cryogel holds great potential for the treatment of DS-contaminated wastewater.

Amphiphilic pH-responsive core-shell nanoparticles can increase the performances of cellulose-based drug delivery systems.

Polymer and nanoparticles (NPs) together are able to form nanocomposite materials that combine the beneficial properties of the traditional single systems. In this work, we propose a stimuli-responsive nanocomposite system which combines pH-responsive NPs with cellulose. Ring opening polymerization (ROP) followed by two reversible addition-fragmentation chain transfer (RAFT) polymerization steps were performed to synthetize ((PHEMA-graft-LA12)-co-PMAA)-b-PDEGMA copolymer characterized by tailored molecular weights and low polydispersity values. Uniform NPs were obtained by nanoprecipitation of the so-obtained copolymer in water. Moreover, drug release studies (using rhodamine b, fluorescein isothiocyanate, pyrene and 5-fluorouracil) at different pHs demonstrated the pH-responsivity of NPs, revealing a significant improvement of hydrophobic molecules release at acidic conditions. In vitro tests verified the biocompatibility of NPs and the efficacy in decreasing cancer cell viability. Finally, NPs were loaded into hydroxypropylmethyl-cellulose-C12 matrix to obtain the final polymer-NPs composite system. The composite systems showed the ability to sustain the release of low steric hindrance drugs loaded with NPs and high steric hindrance ones loaded within the polymeric network. Overall, the proposed pH-responsive drug delivery system represents a co-delivery device which could be applied for localized treatment in different combined therapeutic program.

Gellan-amino acid hydrogel-based bioreactor for optimizing the production of yeast metabolites

Hydrogels mimic natural environments due to their hydrated, polymeric networks which are beneficial for microorganism growth. The substantial water content maintains a consistently moist environment, and porous structure of hydrogel promotes efficient nutrient transfer and cell distribution, offering advantages over traditional liquid bioreactors. While their application in cell immobilization for bioconversion is well-known, their use as a solid-state fermentation matrix remains unexplored. This study is the first attempt to integrate gellan and amino acids to develop an innovative hydrogel bioreactor. The performance of this system was determined by cultivating Rhodosporidium sp. (MTCC 9733) as a model organism and evaluating its metabolite production. Further, gellan and amino acids concentration was optimized using one-factor-at-a-time and D-optimal response surface methodologies to produce β-carotene, lipid, and protein. Additionally, a comparison of productivity, yield, and process economics suggested that novel solid-state hydrogel fermentation approach outperformed classical submerged fermentation in YMB liquid media. Moreover, rheological properties of optimized hydrogel, conducted before and after yeast cultivation, revealed that this system possesses significant mechanical strength and structural integrity. Such attributes render the hydrogel suitable for utilization across multiple fermentation cycles. Hence, this study illustrates the potential of gellan-amino acid hydrogels as sustainable, efficient alternatives to conventional fermentation methods.

A visco-hyperelastic constitutive model of hydrogel considering the coupling effect between segment motion and interchain slippage

Segment motion induces interchain slippage, leading to a complex coupling between hyperelastic and viscoelastic behaviors in hydrogels. Traditional models, which treat these behaviors separately and introduce a coupling free energy, struggle to capture this visco-hyperelastic coupling mechanism accurately. In this work, we develop a visco-hyperelastic constitutive model incorporating viscoelastic contributions into the general hyperelastic free energy to capture the coupling mechanism. The model introduces both the end-to-end distance and the envelope radius to describe the three-dimensional chain conformation. A joint probability distribution of these two parameters is used to capture the relationship between the chain conformation and the chain distribution. We also propose a two-level macro-micro transition framework to link the evolution of end-to-end distance and envelope radius to macroscopic deformations. In the first level of such macro-micro transition, the elongation of individual chains in various directions within the network is mapped to the overall chain elongation. In the second level, both interchain slippage and total chain elongation are incorporated into the overall deformation of the polymer network. A comparison between our predicted results with our experimental data demonstrates the predictability of the new model. Finally, the modeling results show that the interchain slippage always involves two sequential stages, i.e., orientation and relative slippage; and the increasing strain rate enhances the asynchronous responses between segment motion and relative slippage due to multichain interactions, making the viscoelastic responses of hydrogel more obvious.

Wavelength-Dependent Dynamic Behavior in Thiol-Ene Networks Based on Disulfide Exchange.

While latent catalysts have become a well-established strategy for locally and temporally controlling bond exchange reactions in dynamic polymer networks, there is a lack of inherently tailorable systems. Herein, we introduce a thiol-ene network based on disulfide exchange that alters its dynamic properties as a function of the color of light used during the curing reaction. For this purpose, selected allyl-bearing disulfides are synthesized, which are transparent at 450 nm but undergo disulfide scission upon 365 nm light irradiation, as confirmed by UV-vis and EPR measurements. Incorporated into a thiol-ene resin, the wavelength used in the curing reaction defines the dynamic properties of the obtained photopolymer. At 450 nm, photocuring yields a dynamic network with disulfide bonds, which relaxes to 63% of its original stress within 112 s at 160 °C (without the requirement of an external catalyst). In contrast, curing with 365 nm light induces disulfide scission yielding photopolymers, which contain predominately monosulfidic links. The permanent nature of the links effectively prevents relaxation of the polymer within a reasonable period of time, confirming the successful alteration of its dynamic properties simply by the color of the light source used.

PEO-based electrolyte filled with UV-cured 3D cross-linked polymer network for lithium metal batteries

PEO-based electrolyte filled with UV-cured 3D cross-linked polymer network for lithium metal batteries

Efficient capture and dual-model fluorescence detection of ReO4− using a TPE-based pyridinium network

99Technetium is one of the highly radioactive contaminants in nuclear wastewater. ReO4− is an ideal substitute for the safe handling of 99TcO4−, its efficient capture and detection are also significant for scarce rhenium resource recovery. However, designing novel materials for the efficient capture and detection of ReO4− and 99TcO4− is still very challenging. Herein, we establish dual-model fluorescence detection for ReO4− via quick ion exchange by a TPE-based cationic polymeric network (TPDC). TPDC displays good sensor performance for ReO4− accompanying the fluorescence enhancement as well as I− accompanying the fluorescence quenching (on-off). Interestingly, the quenched fluorescence can be reopened by ReO4− (off-on) with a slight increase in the detection limit. Moreover, the adsorption capacity for ReO4− reaches 804.2 mg g−1 and the adsorption equilibrium is achieved within 2 min with a kd value of 6.225×105 mL g−1. This work provides a multifunctional material that manifests efficient capture and dual-model fluorescence detection for ReO4− via quick ion exchange accompanying separate or continuous fluorescence change.

Performance of precursor characteristics in the realisation of geopolymer concrete: a review

Geopolymers are inorganic polymers whose formation is based on the reaction between precursors and reagents, which may be alkaline or acidic. The geopolymerisation process involves the reaction between alumina and silicate materials, known as precursors and reagents, which produces a three-dimensional polymeric network. This review provides a detailed classification of precursors used globally for geopolymer concrete (GPC) production, along with their various oxide contents. As the precursors used in the process of geopolymerisation involve a wide range of variations in their physio-chemical features, it is difficult to control the properties of GPC without going into a micro-level understanding of the precursor characteristics that affect the geopolymerisation mechanism. A comprehensive study was conducted on the influence of these physio-chemical precursor characteristics on the geopolymerisation process and the development of GPC properties. Finally, critical observations are drawn for the design of suitable precursors, along with possible methods to achieve the desired GPC property development.

Feasibility of Recovering and Recycling Polymer Composites from End-of-Life Marine Renewable Energy Structures: A Review

Over the last few decades, several marine renewable energy (MRE) technologies, such as wave energy converters (WECs) and current energy converters (CECs), have been developed. As opposed to traditional materials such as metal alloys, the structure of these technologies is made up of polymer and polymer composite materials. Most structures have been made using thermoset polymer composites; however, since thermoset polymer composites are not recyclable and lack sustainability, and with recent innovations in recyclable resins, bio-based resins, and the development of additive manufacturing technologies, thermoplastic polymers are increasingly being used. Nevertheless, the methodologies for identifying end-of-life options and recovering these polymer composites, as well as the recycling and reuse processes for MRE structures, are not well-studied. Specifically, since these MRE structures are subjected to salinity, moisture, varying temperature, biofouling, and corrosion effects depending on their usage, the recyclability after seawater aging and degradation needs to be explored. Hence, this review provides an in-depth review of polymer composites used in marine applications, the hygrothermal aging studies conducted so far to understand the degradation of these materials, and the reuse and recycling methodologies for end-of-life MRE structures, with a particular emphasis on sustainability.