RSC Applied Polymers最新文献

Stimuli material-based soft actuators is an ever-growing field, offering innovative solutions to the complex challenges of the modern world. Evolving from traditional single stimuli-responsive materials, multifunctional soft actuator hybrids have overcome previous limitations, exhibiting new potential in numerous applications and fields. This review provides initial insights into the recent developments and system integrations of stimuli-responsive polymeric soft actuators from the aspects of material development, mechanism design, and specific applications. It is elucidated that multifunctional soft actuators have versatile activation and can successfully demonstrate unrestricted movements, self-sensing, self-healing, electrochromism, and enhanced mechanical properties. Notably, from rehabilitation and surgical tools in the medical field to improvements in disaster rescue efforts, soft actuators are universally utilized and will be continuously expanding their applicability as research develops.

Hydrogen sulfide (H₂S) imbalance has been implicated in pathologies, and reinstating H₂S homeostasis could be a useful therapeutic strategy. However, delivery of H₂S to the disease site remains a challenge. Functionalised nanoformulations could be used as a strategy to deliver high concentrations of H₂S in a targeted manner. Use of a disease-associated trigger that activates and releases H₂S would provide therapeutic selectivity. As proof-of-concept, synthesis and formulation of block co-polymers bearing a thiocarbamate bond, a carbonyl sulfide (COS) precursor, is described. Activation by hydrogen peroxide (H₂O₂), and a subsequent 1,6-self-immolation process leads to release of COS, which in the presence of carbonic anhydrase is hydrolysed to H₂S. H₂S generation was exemplified by reduction of an azido-pro-fluorophore. Formulation of the polymer resulted in compound vesicles that were able to encapsulate a model drug and could be useful in future biological studies exploring delivery of H₂S as a therapeutic, or to activate azido-masked prodrug/pro-fluorophore in areas of high reactive oxygen species (ROS).

Light drives the curing process in many 3D printing strategies. To broaden the horizons of 3D printing, there is an ongoing push toward longer wavelengths for more effective, gentle, and precise layer photocuring of materials containing fillers or biological substances. Harvesting near-infrared (NIR) light (750–2500 nm) is at the forefront of this endeavour. Multiphoton lithography makes use of infrared light and is an established 3D printing technology, but it does require femtosecond pulse lasers. On the other hand, affordable NIR light sources can be used to 3D print objects with high precision, cytocompatibility, greater functionality, and from a wide range of polymers, but their implementation is not straightforward. In this review, recent studies are presented that advance the field of 3D printing with NIR light. Several cutting-edge technologies are identified, including support-free direct-ink-writing, in vivo bioprinting, and volumetric multimaterial modification, with a final perspective offered on volumetric projection printing toward high-throughput production.

Near net shape manufacture via material extrusion (MEX) of thermoplastics tends to rely on glassy amorphous polymers to avoid stresses generated from crystallization. Polyethylene terephthalate glycol (PETG) has emerged as a high performance, low-cost feedstock for MEX. Crystallization in PETG is suppressed by the inclusion of cyclohexane dimethanol (CHDM) as a comonomer, but CHDM increases the segmental flexibility that can accelerate physical aging. Repeated thermal cycling during MEX printing can accelerate physical aging. Here, we investigate the aging of three commercial PETG filaments with different CHDM content. Thermal analysis demonstrated increased aging as the CHDM content in the PETG increased. Aging of additively manufactured PETG demonstrated that the process path during printing leads to a distribution of aging behavior. The thermal history is spatially dependent, leading to differences in how the PETG ages between layers and location within a printed layer. Additionally, this aging in the MEX printed PETG induced changes to the ultimate tensile stress and elongation at break that are dependent on the filament source. Accelerated aging based on time–temperature superposition demonstrated embrittlement of the printed PETG after the equivalent of 1 year of aging at 25 °C in all cases. However, an unusual increase in both strength and ductility after aging for the equivalent of 30 days of aging at 25 °C was observed with some PETG. Although print conditions are commonly optimized for mechanical performance, long-term aging behavior needs to be understood to ensure reliability of additively manufactured durable goods through their expected lifetime.

Liquid Crystal Display (LCD) mask projection stereolithography (MPSL) is a 3D printing technology that enables the fabrication of complex, high-resolution structures; however, the mechanical properties of MPSL 3D printed objects are often limited by the resins used. This study focuses on developing and characterizing bio-based polyester UV-curable resins with tunable mechanical properties optimized for MPSL. Bio-based polyester resins were synthesized by direct esterification and a polycondensation reaction of itaconic and/or succinic acids with 1,2-propane-, 1,4-butane-, and/or 1,8-octanediols, followed by blending with triethylene glycol dimethacrylate. The bio-renewable nature of the resin components provides several advantages over traditional petroleum-derived resins. The diacid and diol monomers come from renewable feedstocks such as corn, soybean, and vegetable oils rather than finite fossil fuel reserves. Furthermore, bio-renewable materials lower dependence on petrochemicals and increase the sustainability of 3D printing. The effects of the diacid structure and diol chain length on resin properties were systematically investigated. Chemical characteristics were investigated by NMR and FTIR, suggesting successful synthesis of the desired bio-based polyesters. By varying the molecular design, diacid, and diol building blocks, the molecular weight, crosslink density, and mechanical performance were tailored. The liquid resins were characterized by gel permeation chromatography and rheological measurements, and solid UV-cured objects were characterized by static and dynamic tensile testing. Rheological studies confirmed that all resin formulations displayed shear-thinning behaviour, ideal for MPSL printing. Mechanical testing revealed that varying diacid and diol components could modulate tensile elastic modulus and elongation at break from 0.1 to 1.0 GPa and 3.5 to 8.5%, respectively. Printability was assessed by printing a resolution test structure on a LCD 3D printer equipped with a 405 nm LED source. This ability to tailor the properties of bio-based polyester resins by molecular design provides an avenue for fabricating high-performance MPSL-printed objects targeted for specific applications, ranging from prototypes to end-use products.

The rapid increase in energy consumption has heightened interest in harnessing energy from natural mechanical motion. Triboelectric Nanogenerators (TENGs), based on triboelectric and electrostatic induction, offer a promising solution due to their simple structure, low cost, and high energy conversion efficiency under low-frequency motion. This study presents the development of flexible, self-healing triboelectric materials based on viscoelastic polyborosiloxanes (PBS), designed to enhance the performance and environmental adaptability of TENGs. The PBS films exhibit excellent shape adaptability and adhesiveness, enabling them to adhere to irregular surfaces and achieve a self-healing efficiency of 93.2% within 3 minutes at room temperature. The incorporation of boric acid as a cross-linking agent significantly improves the electrical output performance, with the open-circuit voltage (V_oc) and short-circuit charge (Q_sc) increasing by 15% and 20%, respectively, at a boric acid content of 33 wt%. Despite the decrease in tensile strength with higher boric acid content, the PBS-based TENGs maintain stable electrical output under varying load conditions and demonstrate superior performance at low frequencies. The fabricated TENG devices, utilizing PBS and copper films as triboelectric materials, effectively convert a pulsed alternating current into direct current, providing a stable power supply for small electronic devices. These findings underscore the potential of PBS-based flexible, self-healing triboelectric materials for energy harvesting and portable electronic applications, particularly in environments with irregular mechanical sources.

It is challenging to effectively and swiftly address oil and dye pollution. Herein, AM/MAA/HNTs/β-FeOOH sponges with high adsorption performance and strong photocatalytic resistance to oil/dye pollution is reported. β-FeOOH loading increases the specific surface area of the whole material in HNTs, which improves the adsorption of dyes. Composites of HNTs/β-FeOOH of appropriate ratio can realize the adsorption of dyes (C ≤ 20 mg L⁻¹) in 3 min. In addition, due to the photocatalytic properties of β-FeOOH, HNTs/β-FeOOH can also realize the photocatalytic degradation of methylene blue (C = 30 mg L⁻¹) in 30 min. The underwater superoleophobic properties of the AM/MAA/HNTs/β-FeOOH sponge is attributed to improvements of roughness and hydrophilicity. The modified sponge with its special wettability and good adsorption photocatalytic performance enables it to rapidly separate emulsion/dyes (C < 10 mg L⁻¹). This study provides an alternative and effective solution for the problem of oil/dye contamination in complicated wastewater.

Triboelectric nanogenerators (TENGs) have become viable self-powered systems, with great potential to satisfy the increasing demand for portable and adaptable power sources. Using these systems, mechanical vibrations from the motion of vehicles, human beings, rain falls, ocean waves, and air flows can be efficiently captured Depending on the triboelectric series, various materials have been used and explored for TENG applications. In this work, we investigated the triboelectric characteristics of spin-coated polydimethylsiloxane (PDMS) and multiwall carbon nanotube (MWCNT) composite membranes. By adding various concentrations of MWCNTs in PDMS, the charge transfer efficiency was investigated in terms of the current output. At the optimized composition of 0.05 wt% MWCNTs in PDMS, an open-circuit voltage (V_oc) of 110 V and a short-circuit current (I_sc) of 10 μA were observed leading to a power density of nearly 1 W m⁻². Additionally, this composition demonstrated outstanding long-term durability and electrical stability, facilitating energy harvesting during routine activities like jogging and walking using clothing and shoes.

Per- and polyfluoroalkyl substances (PFASs) are a class of toxic, bioaccumulative, and persistent chemicals that pollute natural water sources and the environment, new materials and methods to remove them from water are needed. Anion exchange resins adsorb PFASs through strong electrostatic interactions with negatively charged PFAS molecules with high selectivity and removal efficiency from contaminated water. A series of cross-linked anion exchange resins in the form of polymeric beads were synthesized via inverse suspension polymerization using commercially available cationic monomers, (3-acrylamidopropyl)-trimethylammonium chloride (APTMAC) or diallyldimethylammonium chloride (DADMAC), and the crosslinker, N,N′-methylenebisacrylamide (BisAAm).The resins were evaluated for their ability to remove perfluorooctanoic acid (PFOA) from water and the DADMAC based resin (DR4) with 10 w/w% crosslinker showed the highest efficiency. DR4 exhibits high adsorption capacities of 3300 mg g⁻¹ for PFOA, coupled with rapid adsorption kinetics, achieving equilibrium within an hour. Minimum interference effects from salts, pH variations, and natural organic matter (NOM) were observed and the competitive adsorption study indicated that the presence of other PFASs had no impact on the adsorption efficiency of DR4. DR4 was washed and reused, maintaining its performance after five consecutive PFOA adsorption and desorption cycles.

This study aims to extract anthocyanins (ACNs) from different secondary-agricultural residues and encapsulate them using casein to enhance their stability and bioavailability. Ultrasonic-assisted and conventional extraction methods yielded substantial anthocyanin content from black plum (BP), blueberry (BB), and black wheat bran (WB). After purification, ACNs were encapsulated with casein through the desolvation technique. The optimized anthocyanin-casein-based nanoparticles (A-CNPs) resulted in satisfactory size, polydispersity index (PDI), and zeta potential values of 196–201 nm, 0.184–0.241, and −36 to −34 mV, respectively. BB@A-CNPs resulted in the highest encapsulation efficiency of 92% compared to BP@A-CNPs (83%) and WB@A-CNPs (72%). BP@A-CNPs, WB@A-CNPs, and BB@A-CNPs exhibited high storage stability for 28 days. A-CNPs, particularly BB@A-CNPs, exhibited improved stability towards temperature, pH change, and light. Furthermore, the gastrointestinal stability and release of ACNs from BB@A-CNPs were also assessed using an in vitro digestion model. The controlled release of ACNs and the high antioxidant activity of the final digest suggest improved bioavailability of BB@A-CNPs. Thus, BB@A-CNPs can be used as functional food additives for potentially enriching dairy products with health-promoting anthocyanins. These findings support further development and in vivo validation of the application of these nanonutraceuticals as food additives.