We report bio-derived vitrimeric rubbers with weldability and excellent reprocessability. Reversible-deactivation radical copolymerization of the commercially available terpene-based β-myrcene with 10 to 30 mol % (2-acetoacetoxy)ethyl methacrylate (AAEMA) afforded linear prepolymers, which were cross-linked in a single step treatment with difunctional amine, the vegetable oil-derived Priamine 1075, or trifunctional amine tris(2-aminoethyl)amine (TREN). Decoupling the networks’ backbone structure and cross-linkers led to high tunability of the vitrimers’ final mechanical and rheological properties using prepolymer composition, molecular weight, nature and concentration of cross-linker, and cross-linking density. Glass transition temperature (Tg) of the vitrimers ranged between −49 and −5 °C, while the average elongation and stress at break ranged from ∼83% and 0.18 MPa to ∼30% and 1.68 MPa, respectively from the lowest, 0.12 mol/L, to the highest, 0.98 mol/L, cross-linking densities. The characteristic features of dynamic vinylogous urethane-vitrimers were confirmed over at least three reprocessing cycles by grounding and hot-pressing at 110 °C. No appreciable changes in the ATR-FTIR spectra, Tg, decomposition temperatures, tensile properties, and storage modulus were observed due to reprocessing. Furthermore, the incorporation of 5 mol % epoxy-based glycidyl methacrylate into the prepolymer led to the formation of a network with dual static and dynamic cross-links. Compared to the counterpart network with solely dynamic cross-links, the addition of static cross-links decreased creep by 75% and imparted shape memory effects. This work shows that combining vitrimer chemistry with myrcene is a facile and inexpensive, yet highly versatile method to not only modulate and compensate for the poorer mechanical properties of brush-like terpene-based elastomers but also provides a potential platform for recyclable biobased rubbers with more sophisticated functionalities.

In recent days, the interest toward the development of multicaloric materials for cooling application is increasing, whereas multiferroic materials would be the suitable alternative to the conventional refrigerants. To explore them, the poly(methyl methacrylate)/poly(vinylidenefluoride-co-hexafluoropropylene) (PMMA/PVDF-HFP) blend and PMMA/PVDF-HFP/Zn0.5Cu0.5Fe2O4 flexible multiferroic nanocomposite films were fabricated by the solution casting method. The structural analyses prove that the strong interfacial interaction between the PMMA/PVDF-HFP blend and the Zn0.5Cu0.5Fe2O4 (ZCF) through hydroxyl (−OH) and carbonyl group bonding with PVDF-HFP enhanced the thermal stability and suppressed the electroactive β phase from 67 to 62%. Experimental results show that 10 wt % of superparamagnetic ZCF nanoparticles with a particle size of 6.8 nm induced both the magnetocaloric and magnetoelectric effects in a nonmagnetic PMMA/PVDF-HFP ferroelectric matrix at room temperature. A set of isothermal magnetization curves were recorded in the magnetic field strength of 0–40 kOe and a temperature range of 2–400 K. The maximum magnetic entropy changes (ΔSM) of −0.69 J·kg–1 K–1 of ZCF nanoparticles and −0.094 J·kg–1 K–1 of PMMA/PVDF-HFP/ZCF nanocomposites showed an interesting table-like flat variation in the temperature range of 100–400 K as a function of the magnetic field. The samples display a large temperature span with a relative cooling power of 293 and 40 J·kg–1 for ZCF and PMMA/PVDF-HFP/ZCF, respectively. The magnetoelectric effect of the PMMA/PVDF-HFP/ZCF composite was proved, but it generated only 1.42 mV/m·Oe in the applied field of 5 kOe. Hence, the entropy change of the present nanocomposite was only due to the magnetocaloric effect, where the magnetoelectric cross-coupling coefficient was negligible. The multicaloric effect could be established if the nanocomposite showed a larger magnetoelectric cross-coupling in addition to the magnetocaloric effect. This approach provides the research findings in functional multiferroic polymer nanocomposites for miniaturized cooling devices.

Growing environmental concerns and the goal of a circular economy for polymers necessitate the development of biowaste-based materials and efficient recycling of polymer materials. Here, we developed a series of self-blowing network polyhydroxyurethane (PHU) foams by leveraging the aminolysis and decarboxylation of cashew nutshell liquid (CNSL)-based cyclic carbonate with thiols to release CO2 as a blowing agent; these foams contain up to 80 wt % bio-based content. By systematically varying the blowing agent concentrations, we demonstrated the tunability of the morphologies and mechanical properties of CNSL-based PHU foams. Using dynamic mechanical analysis (DMA), compression testing, and hysteresis testing, we showed that these foams fall into the category of flexible foams with potential as memory foams or resiliency foams. To address the recyclability challenges of thermoset foams, we repurposed these CNSL-based PHU foams into bulk materials and reprocessed them by exploiting the dynamic chemistries of the hydroxyurethane linkages. Notably, the reprocessed bulk networks exhibited full property retention. Moreover, the systematic inclusion of permanent linkages to substitute dynamic cross-links presents an avenue to study the interplay of permanent linkages and cross-link density toward the dynamic characteristics. We showed that average relaxation times and activation energies increase with increasing levels of permanent linkages in the system, demonstrating highly tunable dynamic behaviors in PHU network materials.

Azobenzene polymers with efficient photomediated migration are highly desired because of their potential application in sensors, actuators, and information storage devices. Various methods have been developed to improve photosensitivity of azobenzene polymers; however, performances of the reported polymers so far are still less than satisfactory. While azobenzene polymers of high glass transition temperature (Tg) or melting temperature (Tm) are usually of practical use, photomigration in high Tg (or Tm) azobenzene polymers is difficult because polymer chains are frozen at low temperature. Here, we report the preparation of thermoplastic azobenzene polyurethanes (azo TPUs) with both efficient photomediated migration and excellent mechanical performances. These TPUs are in the phase-separated state with hard microdomains of high Tm embedded in a soft matrix of low Tg. Because of their high Tm, these azo TPUs are mechanically strong with maximum stress exceeding 8 MPa. However, as a result of the two-phase design with the majority of materials being a soft component with low Tg, these azo TPUs also show efficient photomigration of micrometers under UV irradiation (125 mW/cm2, 160 s) despite their high Tm. At higher amplitude of UV light (>500 mW/cm2) and in the presence of a photothermal effect, rare macroscopic mass transportation of centimeter was observed. These azo TPUs may find application in actuators, optical information storage devices, or as optical healable materials.

The soft actuators capable of responding to multiple stimuli and adapting to changing environments have attracted growing interest in the flexible multifunctional materials. However, how to achieve high degree of freedom (DoF), precise control, and complex shape transformation of the multi-stimuli responsive soft actuator, still remains challenging. Here, we report a multi-responsive soft actuator with various controllable sophisticated deformations by integrating a magnetically sensitive elastomer (MSE) with a liquid crystal elastomer (LCE). Through regulating the stimuli strength and the geometrical dimensions and material parameters of elastomers, the bending angle and curling curvature of the actuator are accurately controlled ranging from 0 to 58.9° and from 0.23 to 1.29 cm–1, respectively. The facile material-structural synergistic design drives the complex 3D shape deformations (e.g., bidirectional bending, shrinkage/bending, rolling/bending, and twisting/bending) of the actuator. More importantly, due to its photosensitive characteristics, the shape-morphing of the actuator can be manipulated locally and sequentially, which markedly enriches the DoFs. The flower-shaped actuator displays multiple deformation modes, and the hand-shaped actuator transforms between 8 gestures under the control of laser and magnetic field, proving that the multi-responsive soft actuators have great application potentials in future bioengineering, soft manipulators, and flexible electronics.

The concurrent utilization of chemotherapy and photodynamic therapy (PDT) can successfully slow the growth of tumors while minimizing systemic toxicity. An injectable temperature-sensitive hydrogel was constructed based on Pluronic F127 and phycocyanin (PC). Nanoparticles formed by self-assembly of doxorubicin and ursolic acid (DOX–UA NPS) were further loaded into the hydrogel to give a local drug delivery platform (DOX–UA NPs@Gel). DOX–UA NPs@Gel can be enriched in situ in tumors and continuously release DOX–UA NPs and free PC. UA can promote the responsiveness of tumor cells to DOX. As a natural photosensitizer, PC can produce reactive oxygen species (ROS) when exposed to laser radiation and has significant PDT activity. The MTT assay demonstrated that DOX–UA NPs@Gel under irradiation caused the highest cytotoxicity at 91.6%. The anti-tumor efficiency of various nanoparticles and nanoparticle-loaded hydrogels (the injection dose of DOX is 6 mg/kg) was verified in the H22 tumor-bearing mice (male ICR). In vivo antitumor results demonstrated that DOX–UA NPs@Gel with the combination of chemotherapy and PDT exhibited unique anticancer efficacy with low toxicity. When exposed to radiation after the experiment, the DOX–UA NPs@Gel showed a tumor volume of merely 319 mm3, displaying an exceptional tumor growth inhibition rate of 91.05%. Therefore, the local drug delivery system based on the thermosensitive hydrogel can effectively achieve synergistic antitumor effects.

The integration of catalysts and photosensitizers into a soft matter matrix is an important step for technological deployment and potential repair strategies. Here we present a polyelectrolyte hydrogel platform as a flexible and reusable heterogeneous catalyst for hydrogen evolution reaction (HER), combining polydehydroalanine (PDha) hydrogels with Pt nanoparticles (PtNPs). We demonstrate that the PDha hydrogel can readily adsorb the precursor salt at pH 7, allowing for an in situ capping agent-free synthesis of PtNPs upon UV irradiation. When combined with [Ru(bpy)3]2+ via electrostatic attachment and irradiated under visible light, PtNPs@PDha hybrid hydrogels with 6000 ppm of Pt could evolve 6 μmol H2 after 32 h, which leads to a TON of 60 based on the Pt weight fraction, by adding triethylamine as a sacrificial e– donor in 1:1 MeOH/H2O. If the amount of Pt is reduced to 60 ppm, the obtained TON increased to 350, although the evolved H2 amount was reduced to 0.35 μmol. The water uptake of the hydrogel significantly decreased after the attachment of PtNPs and Ru dye. After photocatalytic HER, the characteristic bands of [Ru(bpy)3]2+ (MC at 352 nm and MLCT at 454 nm) in the absorption spectrum of [Ru]@PtNPs@PDha hybrid hydrogels were shifted, presumably due to the degradation of dyes leading to a broad absorption band stretching toward 600 nm with a shoulder visible at 507 nm. Those degraded dyes were investigated by UV–Vis spectroscopy and could be released at low pH values due to the polyampholytic nature of the surrounding PDha hydrogel. Besides the high activity toward HER, the flexible nature of the herein presented hybrid hydrogels renders these materials interesting and promising systems for heterogeneous light-driven catalysis.

The development of multifunctional epoxy resins that can be degradable and reprocessed is of great significance for the conservation of non-renewable resources and environmental protection. Herein, curing agents based on nitrogen–silicone Schiff base (BOB) and silica-bridged epoxy resin (ETOD) were designed and successfully synthesized. Then, ETOD was cured using BOB to fabricate a multi-silicon-bridge epoxy vitrimer containing dynamic imine bonds (BOB/ETOD). Notably, because of the presence of a large number of siloxane chain segments, BOB/ETOD exhibited excellent flame retardancy (the peak heat release rate (pHRR) was 57.7% lower than that of conventional epoxy resin (DDM/EP) and a carbon residual rate (RC700) of 27.7%, which is 1.6 times higher than that of DDM/EP). Furthermore, the networks of BOB/ETOD could topologically rearrange due to the reversible exchange reaction of imine bonds, making them degradable and reprocessable. Surprisingly, BOB/ETOD also had excellent antimicrobial (the antimicrobial rate was up to 93%) and UV-blocking properties. This work provides a simple and effective solution for the development of multifunctional epoxy-based vitrimers, which is conducive to further expanding the application field of epoxy resins.

Solar vapor generation (SVG) has become a promising and sustainable technology for water purification and desalination. Recently, porous hydrogel-based solar evaporators that combine reduced water evaporation enthalpy and adequate water replenishment have demonstrated a highly effective SVG performance. However, it remains challenging to realize rapid and low-cost fabrication of porous hydrogel evaporators for practical applications. Herein, we report a facile and rapid method (photoinduced polymerization, c.a. 15 s) to fabricate porous composite hydrogels for effective solar seawater evaporation without time-consuming modification and post-treatment. The hydrogel evaporators show laminated composite structures that consist of carbon fiber felt for solar harvesting and an open microporous polyacrylamide-co-poly(N-isopropyl acrylamide) (PAM-co-PNIPAAm) hydrogel for water transport. After composition with photothermal carbon fiber felt (CFF), the CFF/PAM-co-PNIPAAm composite hydrogel evaporators exhibit rapid photothermal heating, in conjunction with the reduced water evaporation enthalpy and continuous water supply for solar evaporation, enabling an evaporation rate of 1.34 kg m–2 h–1 from 3.5 wt % NaCl solution under one sun irradiation, which approaches the theoretical evaporation rate limit of 2D evaporators (1.46 kg m–2 h–1). It is expected that the simple and fast fabrication method presented in this study, without the typical need for expensive raw materials and tedious procedures, will promote the application of hydrogel solar evaporators for water purification.

Thermally conductive adhesives have attracted considerable attention in recent years due to their dual functions in promoting interfacial bonding and thermal transfer. A great number of strategies have been explored for producing them. However, most of them are based on irreversible covalent cross-linking resins, which are difficult to be recycled. Herein, we demonstrate a strategy for in situ producing high-performance, recyclable thermal adhesives from common stocks with a reversibly cross-linkable hyperbranched-star copolymer, HBPE@PSF. The copolymer possesses a hyperbranched polyethylene core covalently bearing multiple polystyrene side chains with small amount of furan moieties, which can be synthesized from commercially available ethylene and styrene as the main monomers. As a stabilizer, the copolymer can effectively promote the exfoliation of hexagonal boron nitride (h-BN) in chloroform under sonication to render high-quality boron nanosheets (BNNSs). Moreover, some of the copolymer can be irreversibly adsorbed on the BNNS surface based on the noncovalent CH−π and π–π interactions. From the resultant nanofiller, BNNS/HBPE@PSF composite adhesives have been successfully prepared through an in situ solution cast process directly with the copolymer as the matrix. After the cross-linking via the Diels–Alder reaction, the resultant adhesives simultaneously exhibit excellent interfacial bonding, thermal transfer, and recyclability, despite their extremely low furan content, 0.30 mol %. This has been confirmed to originate from the unique chain structure of the copolymer, which can form a hyperbranched-star, reversibly cross-linking structure in the composite system. The composite adhesives obtained herein may find their important applications as thermal interface materials in the areas of various electronic products.

Nonsmall cell lung cancer (NSCLC), driven by KRAS gene mutations, is a highly malignant disease currently lacking targeted medicines, except for a specific G12C mutation. However, nanotechnology-based interventions and nanomedicines hold great promise as alternatives to traditional chemotherapy. In this study, we propose a reverse engineering strategy to design and assemble DNA and RNA hybrid origami nanostructures as nanomedicines for the therapy of KRAS-mutated NSCLC. Instead of using M13 DNA as a scaffold for origami design, whose scaffold sequence is constant, the proposed reverse engineering strategy uses a pool of staple sequences that are constant while the scaffold sequences are variable. We conducted a research study on concept verification by designing DNA and RNA hybrid origami nanotubular structures whose staple strands are antisense oligonucleotides (ASON) that are complementary to the full exon regions of KRAS mRNA. The scaffold RNA sequence is thus determined by the ASON sequences and the geometry of the origami design. Once inside the cancer cells, the structure degrades the RNA and releases ASON under the activation of RNase H to exert an antitumor effect. The results from cellular experiments and in vivo studies demonstrated that the hybrid origami structure, composed of DNA and RNA, effectively inhibited both cell proliferation and tumor progression. Remarkably, the proposed reverse engineering method is a universal strategy that can be extended to designing nanomedicines targeting other pathogenic genes and diseases and has good prospects.

We report here the production of higher-order oligomers from the glycolysis of poly(ethylene terephthalate) (PET) by using microwave irradiation in a controlled fashion, instead of its fully glycolyzed product, bis(2-hydroxyethyl)terephthalate (BHET). We show that different catalysts can generate either BHET as the ultimate glycolysis product or higher oligomers of PET under microwave irradiation. Depolymerization of waste PET with an average degree of polymerization (DP) of 417 from water bottles was performed in the presence of 0.25 wt % antimony(III) oxide (Sb2O3) as the catalyst at 240 °C and 400 W microwave power, resulting in an oligomer yield of 96.7% with an average DP of 37. Under these conditions, the conversion of PET to oligomers reached 100% in only 5 min at 240 °C (with a 10 min ramping time) and with a ethylene glycol to PET weight ratio of 2.5. In comparison, under the same reaction conditions, 0.04 wt % of zinc acetate (Zn(OAc)2), a well-known catalyst for PET glycolysis, produces only the BHET monomer in 96.3% yield. Our results demonstrated that by using Sb2O3, the same catalyst that is used extensively for PET synthesis from BHET, under microwave irradiation, the PET glycolysis can be controlled to produce higher PET oligomers as an alternative for a complete chemical depolymerization to the BHET monomer. These oligomers are more suitable for being used as additives for many applications and to produce high-quality second-generation products, including regenerated PET.

Mercury ion (Hg2+) is an extremely hazardous pollutant to humans, soil, and aquatic life. Nanozyme-based sensing approaches are promising for detecting toxic heavy metal ions. However, applying noble metal nanozymes in developing affordable and portable sensors remains largely unexplored. Herein, a gold nanoparticle (AuNP)-based colorimetric sensor was established for the ultra-trace detection of Hg2+ by capitalizing the inherent peroxidase-mimetic features of AuNPs for oxidizing the colorimetric indicator 3,3′,5,5′-tetramethylbenzidine (TMB) in the presence of hydrogen peroxide (H2O2). AuNPs of size less than 10 nm were directly prepared in aqueous media using a stimuli-responsive, poly(ethylene glycol methyl ether methacrylate)-b-poly(dimethylaminoethyl methacrylate (p(PEGEMA)-b-p(DMAEMA)) block copolymer, synthesized through RAFT polymerization. The block copolymers efficiently interacted with Au3+ ions toward the formation of stable, monodispersed AuNPs without additional reducing agents or stabilizers. Using TMB, H2O2, and the AuNP colorimetric system, the concentration of Hg2+ in aqueous media was quantitatively and selectively detected over those of other common interfering metal ions. The selective detection of Hg2+ was promoted by the Au-Hg amalgamation process, which is correlated with intensity of the colorimetric response. Colorimetrically, Hg2+ was linearly measured between 10 nM and 3.5 μM and achieved a detection limit of 0.4 nM. Subsequently, an on-field naked-eye sensing strategy was also developed by integrating the colorimetric sensor on a paper analytical device with a detection limit of 3.5 nM. The efficient colorimetric sensing platform for selective and trace detection of Hg2+ is promising for determining mercury contamination in different water and biological samples.

Liquid-repellent surfaces are beneficial for improving corrosion resistance, anti-biofouling, anti-icing, and reducing material sticking in food, beverages, cosmetics, and medical industries. However, limited research data are available on fabricating sewage water-repellent surfaces, which should repel suspended organic/inorganic and biological matter in addition to water. Herein, we unveil the sewage water repellency and superhydrophobicity of magnetic silicone composites and poly(dimethylsiloxane) (PDMS). Hexagonally arranged microconical pillars (Wenzel roughness of 1.2–2.4) were printed via hot embossing and replica molding methodologies. High static contact angles of ∼160°, low contact angle hystereses of ∼5°, and low roll-off angles of ∼5° were achieved. At least 30 textured silicone composites were fabricated by successively hot embossing from a single custom-made and durable commercializable Ni–steel mold. All of them demonstrated excellent replication efficiency and retained superhydrophobicity and sewage water repellency as a function of embossing cycles. Furthermore, sewage water and deionized water droplets bounced off the silicone composite surface for a Weber number of up to 149, revealing a robust Cassie configuration. Furthermore, textured surfaces retained under-sewage water phobicity for up to 24 h, when submerged at 3 cm depth (0.3 kPa gauge pressure), wherein coated and untextured surfaces have failed just within 15 min, i.e., covered by a liquid film or sticky droplets. Also, textured surfaces inhibited the growth of the Escherichia coli bacterium, while a huge biofilm was observed on the untextured region. Briefly, this is the first demonstration of a one-step, upscalable, and facile hot embossing methodology to manufacture sewage water-repellent silicone composite and PDMS surfaces.

Smart polymer coatings embedding stimuli-responsive corrosion inhibitor nanocarriers are commonly exploited, in the literature, for the development of high-performance active coatings. In this work, high-surface-area amino-functionalized mesoporous silica nanoparticles (MSN-NH2) were developed with a one-step synthesis process and then functionalized with benzoyl chloride (MSN-BC) through a reaction with amino groups. MSN-BC are able to release benzoic acid (BA) in acid and alkaline conditions as a result of the hydrolysis of the pH-sensitive amide bond. MSN-BC were embedded in polymer coatings to exploit the pH-dependent release of corrosion-inhibiting BA. After an in-depth characterization of the developed functional nanoparticles and of their pH-dependent release kinetics of BA, MSN-BC were embedded in an acrylic matrix, realizing coatings for the corrosion protection of aluminum AA2024 alloys. Results demonstrate the effectiveness of the nanoparticles’ porous structure for a high loading of the anticorrosive active agent BA and the long-lasting efficiency of the coating for the corrosion protection of aluminum alloys, as validated by morphological and electrochemical impedance spectroscopy (EIS) measurements. EIS experiments were carried out with up to 21 days of exposure to a corrosive environment, revealing the potentialities of the acrylic coatings embedding MSN-BC for the protection of aluminum alloys.

To replace commercial Nafion membranes in polymer electrolyte membrane fuel cell (PEMFC) applications, high-level research has lately focused heavily on developing polymer nanocomposite membranes with greater proton conductivity (PC), peak power density (PD), open circuit voltage (OCV), and cheaper cost. The aminated triazine containing poly(aryl-aliphatic ethers) (PA-APAAEs) are synthesized via the Schiff base approach, and their functional groups and chemical structure were analyzed using Fourier transform infrared (FTIR), 1H NMR, 13C NMR, and DEPT 13C NMR. PbS nanoparticles (NPs) are prepared through a one-pot hydrothermal method, and their particle size, morphology, and crystallographic nature were investigated through high-resolution transmission electron microscopy (HR-TEM), scanning electron microscopy (SEM), and powder X-ray diffraction (PXRD) analyses. The present study describes a solvent-casting process for producing PbS nanoparticles (1–7 wt %) dispersed in phosphoric acid (PA)-doped triazine ring-containing aminated poly(arylene-aliphatic ethers) (PA-APAAEs) polymer nanocomposite (PNC) foams, and their high-temperature polymer electrolyte membrane fuel cell (HT-PEMFC) performance was evaluated. Additionally, the evaluation of typical physiochemical properties, including ion exchange capacity (IEC), water uptake (WU), swelling ratio (SR), porosity, proton conductivity (PC), and oxidative stability (OS), was done on both bare and PbS NPs-loaded PA/PA-APAAEs polymer nanocomposite (PNC) foams. 5 wt % PbS nanoparticles introduced into PA/PA-APAAEs PNC foams had the greatest IEC rate of 3.46 mmol g–1 at room temperature (RT), as well as a PC value of 3.42 10–2 S cm–1 at 150 °C for the PA-APAAEs foams. Furthermore, under anhydrous circumstances, the fuel cell test of the 5% PbS NPs-loaded PA-APAAEs PNC foam membrane yielded PD and OCV values of 0.525 W cm–2 and 0.55 V at 150 °C, respectively. At 100 °C for 6 h, the PNC exhibited excellent OS with 93.6% deterioration toward the Fenton reagent.

Polyimide (PI)-MoS2/poly(tetrafluoroethylene) (PTFE) composites are prepared using the hot press molding technique at 380 °C and 100 MPa. As the composition is PI-12.5 wt % MoS2-2.5 wt % PTFE, the composite possesses both high strength and excellent self-adaptive lubricating performance in air and vacuum. The average strength/modulus of compression and bending is 183.36 MPa/2.41 GPa and 151.93 MPa/3.98 GPa, respectively. PTFE is primarily transferred to form a continuous transfer film on the counterpart, which makes the coefficient of friction in both air and vacuum smaller than 0.20 at the initial stage. With the wastage of PTFE at the track, MoS2 and PI gradually become dominant for the oriented shear layer in vacuum, which further decreases the coefficient of friction below 0.05. Nevertheless, from the beginning to the end, the transfer of PTFE is more firm in air, which causes PTFE to be the dominant component at the friction interface, resulting in the coefficient of friction below 0.2 for the whole stage. In the mechanism, PTFE is not negatively influenced by water because of its nonpolar and inertial essence, while MoS2 and polar PI are sensitive to oxygen and water, which can restrain the slide within the shear layer and transfer film or between them. Additionally, original flake-like PTFE particles transform to spherulites due to recrystallization during the sintering process, which is beneficial for the enhancement of both strength and self-lubricating performance. The characteristics of this composite, i.e., wear performance, surface, friction interface, microstructure, mechanical performance, and applications in engineering, are systematically studied.

Electrolysis of water to produce hydrogen from renewable electricity is an extremely attractive strategy to reduce energy dependence on fossil fuels. Development of membrane and ionomer materials that maintain high performance with long lifetimes is needed. We developed and investigated the performance and durability of a series of polyethylene-based ABA triblock copolymer anion exchange ionomer and membrane (AEI, AEM) materials for anion exchange membrane water electrolysis. Poly(vinylbenzyl N-methylpiperidinium carbonate)-b-polyethylene-b-poly(vinylbenzyl N-methylpiperidinium carbonate) was synthesized with different hydrophobic/hydrophilic block ratios (1.02:1, 2.58:1, and 4.46:1) resulting in a range of ion exchange capacities (1.1–1.8 meq g–1) and water swelling (23–154%) characteristics. All AEMs showed full anionic dissociation, as evidenced by linear Arrhenius correlations, and excellent carbonate conductivity of 8–94 mS cm–1 at 50 °C. Hydrophilic phase separation may offer superior chemical durability by only wetting the ion-conducting region of the polymer and avoiding attack at the nonwetted backbone. We evaluated the performance and durability of these AEMs as a function of hydrophobic polyethylene (PE) content. The AEM containing the least amount of PE displayed the highest performance of 1 A cm–2 at 2.3 V but degraded at 40 mV h–1 before catastrophically failing after <3 h at 0.5 A cm–2. With greater PE-containing AEMs, the degradation rate was reduced by 3 orders of magnitude with only a 0.2 V increase in voltage. Constant current electrolysis for 50 h resulted in a voltage change of 0.3 mV h–1 in a single-cell water electrolyzer and 1 M potassium carbonate. In a 600 h test, the voltage change in the final 200 h was impressively low for an experimental film, 58 μV h–1. Postmortem analysis indicated that the membrane did not thin and that water becomes more tightly hydrogen-bound in the polymer after electrolysis.

Magnetically active soft materials (MASMs) demonstrate considerable potential for applications in sensors, biomedicines, and bionic and soft robotics. However, owing to the low viscosity of unmodified MASMs with weak molding stacking ability, these materials cannot be printed directly, making the fabrication of MASMs with complex structures. A modified MASM printing ink and its preparation method are proposed for the problem of material and printing process of MASM 3D, and the effects of fumed silica nanoparticles as the modifier on the rheological and mechanical properties of MASM ink were experimentally analyzed. A direct ink writing (DIW) three-dimensional (3D) printing process using MASM printing inks was also proposed. To obtain a highly accurate and stable printing process, the influence of process parameters such as printing speed, nozzle diameter, printing air pressure, and ink viscosity on the ink line width was analyzed. The experimental results show that the MASM objects with different characteristics and structures can be printed stably and with high accuracy, reflecting the feasibility of the proposed MASM ink and DIW 3D printing process. To further validate the characteristics of the DIW 3D-printed MASM objects, a MASM gripper was fabricated using the prepared MASM ink with DIW 3D printing. The magnetization-programmed MASM gripper exhibited excellent magnetic response and excellent gripping and shape-adaptation capabilities. The gripping force was ∼294 mN. Under the driving magnetic field of 270 mT, the gripping force can be more than 1765% of the weight of the gripper (1.7 g). The results of this study show that the proposed MASM printing ink with the DIW 3D printing process can be used for various applications with high performance.

Polyimide (PI) nanofibers are highly suitable for applications in wearable electronic devices due to their excellent mechanical flexibility and good durability. Herein, a low-cost, self-healing flexible pressure sensor (PI@Ag) is demonstrated that is based on silver-nanoparticle-modified polyimide. Uniformly distributed Ag nanoparticles form a three-dimensional conductive network on the nanofiber, which imparts the flexible sensor with high sensitivity (197 kPa–1), wide response range (100 Pa–50 kPa), fast response time (400 ms), low operating voltage (0.02 V), and excellent durability (loading/unloading test of 2000 cycles under 10 kPa). Moreover, the self-healing encapsulating material can protect the inner sensing material when the surface of the sensor is damaged, thereby ensuring the integrity of the pressure sensor. The prepared PI@Ag sensors demonstrate the ability to monitor an entire range of motions when they are attached to human body. Furthermore, equipping the PI@Ag sensors with wireless Bluetooth connectivity enables users to transmit messages via Morse code. The PI@Ag sensors are expected to be widely used in motion monitoring, disease diagnosis, and human–machine interaction.