Polymer Network Structure Research Articles

Synthesis of highly transparent and fast-responding photochromic coating by template method with space-limited domains

The persistent global high-temperature weather warns us that improving energy efficiency and reducing CO2 emissions are urgent. Controlling the solar energy input in buildings using photochromic smart coating can effectively reduce the energy consumption required for cooling. However, it remains a challenge to achieve high transparency and fast photoresponse in organic–inorganic hybrid photochromic smart coating. Herein, we utilize space-limited domains to design a template polymer that facilitates the formation of amorphous WO3 nanodots, thereby enhancing the polymer network structure through hydrogen bonding and dipole–dipole interactions, which endow the smart coating with excellent adhesion strength up to 13 MPa. Notably, the photochromic smart coating with amorphous WO3 nanodots exhibits higher transparency (96.8 %) than conventional glass (91 %), and a wide visible light modulation range of 96.8 %-4.8 %. Based on this, the cooling efficacy of the smart photochromic coating was assessed within a model residence under actual environmental conditions. The inner temperature of the model house was reduced by up to 13 °C, which decreased indoor heat absorption by 25.8 %, significantly improving energy efficiency. This work provides an important and attractive strategy for achieving energy-efficient building materials and addressing global climate warming.

Flexible Highly Thermally Conductive PCM Film Prepared by Centrifugal Electrospinning for Wearable Thermal Management

Personal thermal management materials integrated with phase-change materials have significant potential to satisfy human thermal comfort needs and save energy through the efficient storage and utilization of thermal energy. However, conventional organic phase-change materials in a solid state suffer from rigidity, low thermal conductivity, and leakage, making their application challenging. In this work, polyethylene glycol (PEG) was chosen as the phase-change material to provide the energy storage density, polyethylene oxide (PEO) was chosen to provide the backbone structure of the three-dimensional polymer network and cross-linked with the PEG to provide flexibility, and carbon nanotubes (CNTs) were used to improve the mechanical and thermal conductivity of the material. The thermal conductivity of the composite fiber membranes was boosted by 77.1% when CNTs were added at 4 wt%. Water-resistant modification of the composite fiber membranes was successfully performed using glutaraldehyde-saturated steam. The resulting composite fiber membranes had a reasonable range of phase transition temperatures, and the CC4PCF-55 membranes had melting and freezing latent heats of 66.71 J/g and 64.74 J/g, respectively. The results of this study prove that the green CC4PCF-55 composite fiber membranes have excellent flexibility, with good thermal energy storage capacity and thermal conductivity and, therefore, high potential in the field of flexible wearable thermal management textiles.

Synergistic enhancement of magic triangle properties of PC tread stocks modified by amine-capped trans-1,4-poly (butadiene-co-isoprene)

The development of high-performance “green tires” with synergistically improved “magic triangle” properties like lower rolling resistance, higher wet-skid resistance and higher abrasion resistance has always been a hot issue. In this work, an effective strategy for developing high-performance “green tires” with simultaneously improved “magic triangle” properties of solution-polymerized styrene-butadiene rubber (SSBR)/cis-1,4-polybutadiene rubber (BR) nanocomposites modified by amine-capped trans-1,4-poly(butadiene-co-isoprene) copolymers (F-TBIR) was proposed. A series of F-TBIR with 10–60 mol% amine-capped efficiency (CE) and 30-90 × 104 weight-average molecular weight (Mw) were synthesized by using heterogeneous TiCl4/MgCl2–Al(i-Bu)3 Ziegler-Natta catalyst with dicyclohexylamine (DCHA) as chain transfer agent (CTA). With the increase in CE of F-TBIR, the silica-filled SSBR/BR/F-TBIR compounds exhibited improved green strength, modulus at 100 % elongation and bound rubber, and their vulcanizates showed synergistically improved “magic triangle” properties like obviously reduced rolling resistance and abrasion loss, and increased wet-skid resistance. It was found that the incorporation of 10 phr F-TBIR3 with CE of 60 mol% and Mw of 32 × 104 resulted in highly expected properties of the SSBR/BR/F-TBIR3 nanocomposite. The contribution mechanism of F-TBIR3 was discussed based on the improvements of polymer network structures and filler network structures. This work is expected to provide an effective strategy to construct the desired network structures for high-performance rubber composites.

Electrically conductive functionalization of cured polyether ether ketone with improved bioactivity by surface-polymerization of polyaniline

The electrically conductive polyether ether ketone (PEEK) holds great promise for antibacterial and cell growth promotion under electrical stimulation, making it a promising material for next-generation implants. However, it is a significant challenge for electrically conductive functionalization of PEEK, especially for cured or shaped PEEK. In addition, PEEK’s bioactivity is still underdeveloped at present. Here, an electrically conductive PEEK with improved bioactivity is prepared through surface-polymerization of polyaniline (PANI) in the shell layer of cured PEEK. Impressively, an extremely high conductivity of 5.2 × 10−2 S/cm is achieved for the conductive PEEK among all the reported PANI/PEEK composites or blends with the optimal conductivity of 3.0 × 10−4 S/cm. It has been demonstrated that the conductive shell layer of the conductive PEEK features a PANI/PEEK semi-interpenetrating polymer network structure, explaining its conductivity. Improved cell proliferative activity is also disclosed for the conductive PEEK compared to that of the pure PEEK, and good biocompatibility and osteogenesis properties are further confirmed for the fabricated conductive PEEK scaffold. This conductive functionalization approach offers a significant advancement for developing next-generation biological implants and could be applied to other cured polymers as well.

Modulating the Li‐Ion Transport Pathway of Succinonitrile‐Based Plastic Crystalline Electrolytes for Solid‐State Lithium Metal Batteries

AbstractSuccinonitrile (SCN) based plastic crystal electrolytes (SPCEs) have attracted much attention for lithium metal batteries due to their considerable ionic conductivity and thermal stability. Insufficient mechanical properties, weak reductive stability, and the presence of free SCN molecules can result in adverse interfacial reactions. Polymer introduction has been explored to address these challenges. However, the introduction of polymer affects the SCN state, leading to reduced ionic conductivity, potentially due to limited segmental motion of the polymer at room temperature. Herein, a cross‐linked network polymer strategy is proposed to modify the Li‐ion transport pathway in SPCE, aiming to significantly improve the ionic conductivity. The strong interaction between the polymer matrix and SCN enhances their mutual solubility, reduces the crystallinity of SCN, and forms a rapid conduction pathway (polymer—[SCN—Li+]). The ionic conductivity of SPCE increases to 1.28 mS cm−1, with the Li‐ion migration number (tLi+ ) also rising to 0.7. Electrochemical performances in Li symmetrical, Li||LiFePO4 and Li||LiNi0.8Co0.1Mn0.1O2 cells show significant improvement at both room temperature and 0 °C. These findings suggest that designing polymer network structures in SPCEs holds promise for solid‐state lithium metal battery applications.

Coating effect of polyurethane-layered double hydroxide nanocomposite on steel

The motivation behind this work is the preparation of polyurethane-magnesium aluminum layered double hydroxide (PU-LDH) nanocomposite and its application as a coating for steel protection. The coating was prepared with different doses of LDH, ranging from 0 to 2% of the coating weight. The effect of different concentrations on the mechanical, adhesion, and surface properties of PU coating is studied. Firstly, LDH was prepared via the coprecipitation process and then distributed in PU matrix. The nanocomposites were then crosslinked in the form of coating layers on steel. The preparation of the thermally stable crystalline LDH nanoparticles with 89 nm particle size was confirmed by FTIR, XRD, DLS, and TGA. SEM photos showed the dispersed and intercalated structure. The coating characteristics demonstrate that addition of LDH decreased the drying time and increased the dry film thickness of PU up to 1.5% due to the crosslinking between the large surface area nanofiller and polyurethane matrix. Furthermore, the prepared LDH nanofiller increased the adhesion strength, impact resistance, abrasion resistance, modulus, and flexibility of PU due to the strong polymeric network structure. The 2% nanocomposite coating shows poor properties due to the excess concentration and heterogeneous dispersion of nanoparticles within the PU polymer. The resistance to fire and some chemicals was supported by the thermally and physically stable LDH nanoclay. The former characterizations state that the proposed PU-LDH nanocomposite is an enhanced and applicable coating.

Comprehensive Characterization of Drying Oil Oxidation and Polymerization Using Time-Resolved Infrared Spectroscopy.

Drying oils like linseed oil are composed of multifunctional triglyceride molecules that can cure through three-dimensional free-radical polymerization into complex polymer networks. In the context of oil paint conservation, it is important to understand how factors like paint composition and curing conditions affect the chemistry and network structure of the oil polymer network and subsequently the links between the structure and long-term paint stability. Here, we employed time-resolved ATR-FTIR spectroscopy and comprehensive data analysis to study the curing behavior of five types of drying oil and the effects of curing temperature as well as the presence of a curing catalyst (PbO). Extracted concentration curves of key reactive functional groups point to a phase transition similar to a gel point that is especially pronounced in the presence of PbO, after which curing reactivity slows down dramatically. Analysis of kinetic parameters suggests that PbO induces a network structure with a more heterogeneous cross-link density, and the ATR-FTIR spectra indicate lower levels of oxidation in those cases. Finally, lower temperatures appear to favor the formation of carboxylic acid groups in oil mixtures with PbO.

Gels/Hydrogels in Different Devices/Instruments-A Review.

Owing to their physical and chemical properties and stimuli-responsive nature, gels and hydrogels play vital roles in diverse application fields. The three-dimensional polymeric network structure of hydrogels is considered an alternative to many materials, such as conductors, ordinary films, constituent components of machines and robots, etc. The most recent applications of gels are in different devices like sensors, actuators, flexible screens, touch panels, flexible storage, solar cells, batteries, and electronic skin. This review article addresses the devices where gels are used, the progress of research, the working mechanisms of hydrogels in those devices, and future prospects. Preparation methods are also important for obtaining a suitable hydrogel. This review discusses different methods of hydrogel preparation from the respective raw materials. Moreover, the mechanism by which gels act as a part of electronic devices is described.

Ultratough Supramolecular Polyurethane Featuring an Interwoven Network with Recyclability, Ideal Self-Healing and Editable Shape Memory Properties.

Developing multifunctional polymers with excellent mechanical properties, outstanding shape memory characteristics, and good self-healing properties is a formidable challenge. Inspired by the woven cross-linking strategy, a series of supramolecular polyurethane (PU) with an interwoven network structure composed of covalent and supramolecular cross-linking nodes have been successfully synthesized by introducing the ureido-pyrimidinone (UPy) motifs into the PU skeleton. The best-performing sample exhibited ultrahigh strength (∼77.2 MPa) and toughness (∼312.7 MJ m-3), along with an ideal self-healing efficiency (up to 90.8% for 6 h) and satisfactory temperature-responsive shape memory effect (shape recovery rates up to 96.9%). Furthermore, it ensured recyclability. These favorable properties are mainly ascribed to the effective dissipation of strain energy due to the disassembly and reconfiguration of supramolecular nodes (i.e., quadruple hydrogen bonds (H-bonds) between UPy units), as well as the covalent cross-linking nodes that maintain the integrity of the polymer network structure. Thus, our work provides a universal strategy that breaks through the traditional contradictions and paves the way for the commercialization of high-performance multifunctional PU elastomers.

Chitosan-derived activated carbon/chitosan composite beads for adsorptive removal of methylene blue and acid orange 7 dyes

In this study, a chitosan/activated carbon composite was developed for the sustainable removal of dye pollutants from activated carbon derived from chitosan. First, chitosan was converted into chitosan-derived activated carbon (C-AC) with a large Brunauer-Emmett-Teller (BET) surface area of 2428 m2/g through carbonization using a potassium hydroxide (KOH) chemical activator. To enable simple separation from contaminated water and sustainable use in the adsorption process, the generated C-AC was incorporated into a bead-type, stable three-dimensional chitosan polymer network structure. The prepared C-AC-incorporated chitosan beads showed excellent adsorption capacity for the anionic acid orange 7 (AO) (511.38 mg/g) and the cationic methylene blue (MB) (413.08 mg/g). In addition, it maintained structural stability even in various pH environments and could be easily separated from contaminated water. The C-AC-incorporated chitosan beads showed excellent reusability and durability, maintaining at least 82% and 86% removal efficiencies for AO and MB dyes even after five reuses. This study suggests the potential use of chitosan as an eco-friendly adsorbent that can be utilized simultaneously as an activated carbon precursor and as a matrix for robust bead-like polymer composites.

Fabrication of Single-Ion Conductors Based on Liquid Crystal Polymer Network for Quasi-Solid-State Lithium Ion Batteries.

Single-ion conductive polymer electrolytes can improve the safety of lithium ion batteries (LIBs) by increasing the lithium transference number (tLi+) and avoiding the growth of lithium dendrites. Meanwhile, the self-assembled ordered structure of liquid crystal polymer networks (LCNs) can provide specific channels for the ordered transport of Li ions. Herein, single-ion conductive nematic and cholesteric LCN electrolyte membranes (denoted as NLCN-Li and CLCN-Li) were successfully prepared. NLCN-Li was then coated on commercial Celgard 2325 while CLCN-Li was coated on poly(vinylidene fluoride-hexafluoropropylene) film, coupled with plasticizer, to make NLCN-Li/Cel and CLCN-Li/Pv quasi-solid-state electrolyte membranes, respectively. Their electrochemical properties were evaluated, and it was found that they possessed benign thermal stability and electrolyte/electrode compatibility, high tLi+ up to 0.98 and high electrochemical stability window up to 5.2 V. A small amount (0.5M) of extra Li salt added to the plasticizer could improve the ion conductivity from 1.79 × 10-5 to 5.04 × 10-4 S cm-1, while the tLi+ remained 0.85. The assembled LFP|Li batteries also exhibited excellent cycling and rate performances. The orderliness of the LCN layer played an important role in the distribution and movement of Li ions, thereby affecting the Li deposition and growth of Li dendrites. As the first report of nematic and cholesteric LCN single-ion conductors, this work sheds light on the design and fabrication of ordered quasi-solid-state electrolytes for high-performance and safe LIBs.

Formation of Self-Healing Granular Eutectogels through Jammed Carbopol Microgels in Supercooled Deep Eutectic Solvent.

Typically, gel-like materials consist of a polymer network structure in a solvent. In this work, a gel-like material is developed in a deep eutectic solvent (DES) without the presence of a polymer network, achieved simply by adding microgels. The DES is composed of choline chloride and citric acid and remains stably in a supercooled state at room temperature, exhibiting Newtonian fluid behavior with high viscosity. When the microgel (Carbopol) concentration exceeds 2 wt %, the DES undergoes a transition from a liquid to a soft gel state, characterized as a granular eutectogel. The soft gel characteristics of eutectogels exhibit a yield stress, and their storage moduli exceed the loss moduli. The yield stress and storage moduli are observed to increase with increasing microgel concentration. In contrast, the ion conductivity decreases with increasing microgel concentration but eventually levels off. Because the eutectogel can dissolve completely in excess water, it is a physical gel-like material, attributed to the densely packed structure of microgels in the supercooled DES. Due to the absence of networks, the granular eutectogel has the capability to self-heal simply by being pushed together after being cut into two pieces.

Property improvement of epoxy emulsified asphalt modified by waterborne polyurethane in consideration of environmental benefits

Waterborne epoxy modified emulsified asphalt (EMEA) has the shortcomings of insufficient toughness and poor aging resistance, which limits its application of low-carbon cold-paving technology in plateau zones. To obtain a cold-mix asphalt binder with excellent performance, waterborne polyurethane (WPU) was utilized to modify EMEA in this work. Properties, modification mechanism, action process, environmental benefits, and cost-benefit of composite-modified emulsified asphalt (CMEA) were analyzed. Results show that CMEA had good rutting resistance, low-temperature rheological, tensile toughness, adhesion with aggregate and moisture damage resistance, and aging resistance properties. These were closely related in that WPU was cross-linked with the waterborne epoxy resin (WER) to form an interpenetrating polymer network (IPN) structure, when the space network structure of WER and the soft and hard segments of WPU worked together. Based on the above results, it was recommended that EA containing 4.0 wt% WER was modified by 7.5 wt% WPU to achieve the best pavement properties. Furthermore, it was discovered that a physical process by which WER and WPU modified EA, served as a skeleton connection and toughening agent. CMEA has excellent performance and is especially suitable for use in low-temperature and strong aging areas, while can bring good environmental benefits.

Study on the rheological properties and salt resistance mechanism of an amphiphilic polymer with twin-tailed group

Partially hydrolyzed polyacrylamide (HPAM) is the most widely used polymer for oil recovery. Its thickening ability has been severely compromised in high salinity reservoirs. To improve polymer viscosity in high salinity reservoirs, a twin-tailed amphiphilic polymer P(AM/AMPS/DtC18) was developed by radical copolymerization method using AM, AMPS and DtC18 monomers, abbreviated as PAAD18. The contrast polymer P(AM-AMPS) was prepared by the same method and reaction conditions. The structure of PAAD18 was characterized by Fourier Transform Infrared Spectroscopy (FTIR) and H Nuclear Magnetic Resonance Spectra (1H NMR). The relationship between its rheological properties and microstructure was studied using rheological analysis and Scanning Electron Microscope (SEM). The mechanism of salt resistance was revealed. The results show that under the condition of XJ reservoir with 98558 mg/L and 40℃, the viscosity of PAAD18 with concentration of 2200 mg/L is 25 mPa·s. PAAD18 has better temperature and salt resistance than HPAM and P(AM-AMPS). P(AM-AMPS) has better temperature resistance and salt resistance than HPAM. The salinity ranges from 0 to 5 × 104 mg/L, the viscosity of PAAD18 is reduced due to the action of electrostatic shielding. At a salinity of 5 × 104 mg/L, the electrostatic shielding effect and the hydrophobic association effect reach a balanced point, and the solution viscosity is the lowest. The salinity increases from 5 × 104 mg/L to 15 × 104 mg/L, then the hydrophobic association is enhanced due to the increased polarity of the solution. It was found that the polymer network structure of PAAD18 was more complex, the viscosity of the solution increased instead. The salt thickening properties were demonstrated in the rheology measurement. This work provides a new material for polymer flooding technology in high salinity reservoirs, with good application potential and guiding significance.

Atomic-molecular perspectives on local high-temperature structure and transport properties of CaCO3-foamed glass

Significant gaps remain in understanding of gas-melt interfaces in foamed glass systems. We attempt to address these gaps by reporting on the transition of local structure, ionic (molecular) diffusion, and melt viscosity of CaCO3-foamed soda-lime-silica glass using molecular dynamics calculations and experimental analyses. Our calculations show that despite the continual increase in network modifying CaO, the melt network experiences an abnormal polymerization process in the initial stage because of Na ion penetration from the melt skeleton to the interface. The percolation probability decays from the surface to the center of melt because of the gradual polymerized network structure, boosting nonmonotonic changes in the [SiO4] species, equilibrium constants, and average residual charge per O atom. Furthermore, the diffusion capacities of melt ions and CO2 molecules peak at 6 wt% CaCO3 addition, attributed to the combined effects of melt depolymerization and interface constraint. The viscosity jump occurring at 1 wt% CaCO3 addition results in the optimal sample with an even cellular glass framework and strong matrix. These findings contribute to the precise control of foamed glass with optimal performance.

Coupling of Ethylene-Oxide-Based Polymeric Network Structure and Counterion Chemistry to Ionic Conductivity and Ion Selectivity

Coupling of Ethylene-Oxide-Based Polymeric Network Structure and Counterion Chemistry to Ionic Conductivity and Ion Selectivity

Ultraviolet-cured heat-resistant and stretchable gel polymer electrolytes for flexible and safe semi-solid lithium-ion batteries

Lithium-ion (Li-ion) batteries assembled with gel polymer electrolytes (GPEs) are predicted to increase battery energy density while maintaining battery safety. In this work, poly (vinylidene fluoride-co-hexafluoropropylene) (PVDF-HFP) is successfully used as a polymer matrix to prepare a new kind of GPE (PHHNT) by ultraviolet (UV) curing technology. The polymer network structure formed by photopolymerization technology significantly enhances the tensile properties of the electrolyte. Lithium bis(trifluoromethanesulfonyl)imide (LiTFSI) improves the concentration and transport efficiency of lithium ions in the electrolyte as well as the ionic conductivity (1.22 × 10−3 S cm−1) of the GPEs. In addition, the unique tubular structure of the halloysite nanotube (HNT) and the opposite charges carried by the inner and outer surfaces provide additional channels for the lithium salt and facilitate its dissociation. This enhances the expedited movement of Li+ inside the electrolyte, while simultaneously improving the electrochemical and thermal durability of the electrolyte. The assembled LiFePO4 (LFP)/PHHNT/Li battery has an initial discharge-specific capacity of 140.5 mAhg−1 at a current density of 0.5C, showing a high capacity retention rate of 89 % after 120 cycles. The design of this composite material significantly improves the overall performance of the electrolyte and is more suitable for flexible and safe solid-state Li-ion batteries.

Gum Arabic microgel–based biomimetic waterborne anticorrosive coatings with reinforced water and abrasive resistances

The inadequate water resistance and mechanical properties of waterborne anticorrosive coatings is a serious problem that leads to coating failure. When the bark of acacia trees sustains damage, the liquid Gum Arabic (GA) that oozes from the trunk coagulates at the site of injury to safeguard it, which is called “gummosis” self-protection. Inspired by this, biomimetic GA microgel–based waterborne anticorrosive coatings are designed. Microgel exhibits a crosslinked polymer network structure with a combination of advantageous characteristics derived from both solids and liquids. By encapsulating the liquid corrosion inhibitors (MeBT) within the solid microgel matrix, the coating system is endowed with self-protective capabilities. The as-prepared GAMG–MeBT microgels are introduced into waterborne epoxy (WE) matrix and sprayed onto the surface of Q235 steel. Corrosion studies reveal the 3.0-wt% GAMG–MeBT/WE coating exhibits an impedance modulus value in the low-frequency region (Z0.01Hz) of 1.37 × 109 Ω cm2 after immersing in 3.5-wt% NaCl solution for 60 days, which is nearly two orders of magnitude higher than that of the pure WE coatings. Moreover, the coatings display improved water resistance, enhanced abrasive resistance, and active corrosion protection. This work provides a new approach to solving the failure of WE anticorrosive coatings.

Synthesis of PDMS Chain Structure with Introduced Dynamic Covalent Bonding for High‐Performance Rehealable Tactile Sensor Application

AbstractIn addressing the increasing demand for wearable sensing systems, the performance and lifespan of such devices must be improved by enhancing their sensitivity and healing capabilities. The present work introduces an innovative method for synthesizing a healable disulfide bond contained in a polydimethylsiloxane network (PDMS−SS) that incorporates ionic salts, which is designed to serve as a highly effective dielectric layer for capacitive tactile sensors. Within the polymer network structure, the cross‐linking agent pentaerythritol tetrakis 3‐mercaptopropionate (PTKPM) forms reversible disulfide bonds while simultaneously increasing polymer softness and the dielectric constant. The incorporation of dioctyl sulfosuccinate sodium salt (DOSS) significantly improves the capacitance and sensing properties by forming an electrical double‐layer through interactions between the electrode charge and salt ions at the contact interface. The developed polymer material‐based tactile sensor shows a strong response signal at low pressure (0.1 kPa) and maintains high sensitivity (0.175 kPa−1) over a wide pressure range (0.1–10 kPa). It also maintains the same sensitivity over 10 000 repeated applications of external pressure and is easily self‐healed against mechanical deformation due to the dynamic disulfide covalent bonding, restoring ≈95% of its detection capacity.

Bulk transparent supramolecular glass enabled by host–guest molecular recognition

Supramolecular glass is a non-covalently cross-linked amorphous material that exhibits excellent optical properties and unique intrinsic structural features. Compared with artificial inorganic/organic glass, which has been extensively developed, supramolecular glass is still in the infancy stage, and itself is rarely recognized and studied thus far. Herein, we present the development of the host–guest molecular recognition motifs between methyl-β-cyclodextrin and para-hydroxybenzoic acid as the building blocks of supramolecular glass. Non-covalent polymerization resulting from the host–guest complexation and hydrogen bonding formation enables high transparency and bulk state to supramolecular glass. Various advantages, including recyclability, compatibility, and thermal processability, are associated with dynamic assembly pattern. Short-range order (host–guest complexation) and long-range disorder (three dimensional polymeric network) structures are identified simultaneously, thus demonstrating the typical structural characteristics of glass. This work provides a supramolecular strategy for constructing transparent materials from organic components.