ACS Applied Polymer Materials最新文献

While there has been an ongoing effort to develop environmentally friendly multifunctional films made from natural polymers and renewable resources, there are still challenges in realizing versatility through a simple and green process. Here, we use aqueous alkali to rapidly dissolve modified cellulose fibers above 0 °C within minutes to prepare cellulose hydrogel substrate. The modified cellulose can be commercially obtained from carboxymethyl cellulose manufacturing with low cost. Subsequently, a biodegradable multifunctional all-biomass composite film is obtained by wrapping sodium lignosulfonate (LSS) and phosphorylated sodium alginate (PSA) molecules in cellulose hydrogel. The films exhibited excellent UV protection, blocking 86–99.3% of UV-A and 99.6–100% of UV–B radiation. Meanwhile, the films blocked 57.4–90.7% of high-energy blue light (HEBL, 400–450 nm) and maintained 66.2–80% transparency at 600 nm. The films effectively block blue light from sources such as computer screens, mobile phones, and lighting systems by means of light absorption. The films outperformed commercial shielding films in UV and HEBL blocking. Notably, the films acquired excellent flame-retardant performance with the addition of PSA, achieving a high limiting oxygen index (LOI) of 33.3%. In comparison with the original one, the composite film exhibited a 75.6% reduction in peak heat release rate and an 84.6% decrease in total heat release. Moreover, the films have ideal biodegradability and mechanical strength, with a tensile strength exceeding 98 MPa. This sustainable and clean strategy would direct all-biomass films toward diversified applications.

Research on solar-driven photothermal degradation for wastewater purification has gained considerable attention due to its utilization of green energy and environmental sustainability. Rapid industrialization has exacerbated water pollution, particularly from tetracycline, posing significant threats to human health and ecosystem stability. Inspired by bamboo architecture, a vertically aligned, bamboo-like structural aerogel enhanced with electron transport capacity has been successfully developed for the photothermal degradation of tetracycline. This bamboo-like aerogel facilitates charge separation and transport through the link of titanium dioxide and graphene. Upon exposure to solar irradiation, hole–electron pairs are generated along the bamboo-like channels, reaching adsorption equilibrium and achieving an impressive tetracycline degradation rate of 99.97%. The aerogel maintains a photothermal degradation efficiency exceeding 85% after seven operational cycles, demonstrating excellent recycling stability and potential for practical applications. Furthermore, the aerogel demonstrates exceptional photocatalytic and photothermal degradation capabilities under alkaline conditions. This research suggests that the bamboo-like structural aerogel offers an efficient solution for photothermal degradation, providing an innovative approach to managing water pollution and addressing freshwater scarcity.

Ectomesenchymal stem cells (EMSCs) loaded with bone tissue-engineered scaffolds are considered a promising strategy for treating bone defects. However, the therapeutic efficacy of this approach is not solely dependent on the biological characteristics of EMSCs but also on the physicochemical properties of the scaffold. In particular, the elastic modulus of the scaffold plays a crucial role, yet its effects on the biological behavior of EMSCs remain poorly unclear. In this study, we constructed a composite scaffold from chitosan and polycaprolactone, which allowed an adjustable elastic modulus. We investigated the effects of these scaffolds on the adhesion, proliferation, and osteogenic differentiation of EMSCs in vitro. A suitable composite scaffold for EMSC osteogenic differentiation was first identified through early and late osteogenesis. Additionally, the composite scaffold was confirmed to promote the osteogenic differentiation of EMSCs through piezo1/YAP signaling. Finally, we demonstrated that the composite scaffold loaded with EMSCs ultimately promoted skull bone regeneration in a rat model. These findings provide valuable insights into the strong application prospects of EMSC-loaded scaffolds for bone defect therapy.

Although RNA therapeutics hold great promise for treating different diseases, their administration across physiological barriers remains challenging. This study explores a supramolecular (SM), bioerodible, and injectable hydrogel, composed of an ad hoc synthesized Poloxamer 407-based poly(ether urethane) (PEU) and α-cyclodextrins (α-CDs), as a carrier for localized delivery of poly(β-amino ester) (PBAE) and siRNA polyplexes. Polyplexes assembled within α-CDs showed higher sizes (150–300 nm) and positive charges (+20 to +30 mV) compared to those in HEPES buffer (<100 nm, −20 to +20 mV). SM hydrogels, prepared by mixing aqueous solutions of PEU and α-CDs at final concentrations of 0.9–1.4 and 10% w/v, respectively, preserved thixotropic and self-healing characteristics after polyplex embedding. Intact polyplexes were released from the hydrogel over 48 h and showed efficient gene knockdown in phagocytic cells. These findings underscore the potential of SM hydrogels as gene delivery vehicles, premised upon their injectability and favorable release profiles.

The threats posed by flame burning and falling debris during fires are immense, making the development of flame-retardant and impact-resistant protective devices an urgent necessity. By employing particle reinforcement technology, ammonium polyphosphate (APP) particles were introduced into the shear-stiffening gel (SSG). The results of rheological experiments demonstrate that the SSG filled with APP particles (SSG@APP) can significantly enhance the storage modulus (G′) of the matrix SSG. The Prony series model effectively predicted SSG@APP’s storage modulus-frequency curve (R² > 0.99). The shear stress–strain curve of SSG@APP demonstrates a high degree of consistency with the rate-dependent Cowper-Symonds model. Regarding impact protection, SSG@APP can dissipate 82% of the impact force under the condition of an impact height reaching 20 cm, which mainly stems from the shear-stiffening effect. When SSG is filled with 40% APP particles, the material can meet the V-0 vertical burning standard and has a measured limiting oxygen index (LOI) value of 30%. The total heat release (THR) values of SSG and SSG@APP were measured as 81 and 54 MJ/m², respectively, indicating that SSG@APP exhibits superior flame-retardant properties. Therefore, SSG@APP is not only highly suitable for manufacturing wearable protective devices but also effective in safeguarding fragile/flammable items.

Ethyl cellulose (EC) has been widely used in pharmaceutical and food packaging aspects due to its biodegradability and antimicrobial properties; however, it suffers from excessive brittleness, which must be plasticized to meet the requirement of industry. Herein, hemicellulose polyether glycidyl ether (EPPG) was developed as a plasticizer for EC using viscose waste liquor as feedstock through etherification and epoxidation. When 40 wt % EPPG (based on the weight of EC) was blended with EC, the elongation at break was increased from 3.0% (Neat EC) to 54.5% (EC/EPPG), while the glass transition temperature of EC/EPPG decreased from 137.5 °C (Neat EC) to 73.1 °C, which were better than those of EC plasticized by 40 wt % DOP (dioctyl phthalate) (EC/DOP). Comprehensive characterization through XRD, FT-IR spectroscopy, and quantum chemical calculations provides molecular-level evidence of strong intermolecular interactions between EPPG and the EC matrix, imparting excellent compatibility and plasticization. The EPPG-plasticized EC films exhibit decent stability characteristics, showing only 15.5% mass loss in n-hexane migration tests and maintaining thermal stability up to 276.9 °C (T_5%). In contrast, the migration rate of EC/DOP films is as high as 25.0%, and the T_5% is only 254.2 °C. This work represents a significant advancement in sustainable material design, simultaneously addressing two critical challenges: the valorization of viscose waste stream components and the development of high-performance, biobased alternatives to conventional plasticizers.

Color-changing materials make up a category of smart materials capable of exhibiting chromatic transitions in response to environmental stimuli. Certain thermochromic materials exhibit tunable optical transmittance during chromatic transitions, allowing for dynamic modulation of solar radiation in energy-efficient window applications. In this work, we develop a low-cost thermochromic poly(N-isopropylacrylamide)/carboxymethyl cellulose sodium/poly(ethylene glycol) (PCP) composite, achieving excellent light modulation and indoor temperature regulation capabilities. The introduction of CMC and PEG significantly enhanced the uniform dispersion of PNIPAM, thereby endowing the material with a highly efficient transition from transparent to opaque. Meanwhile, the results show that the PNIPAM/CMC/PEG smart window has high luminous modulation (ΔT_lum = 99.20%) with approximately 100% luminous transmission (T_lum = 99.29%) at 25 °C and approximately 0% transmission (T_lum = 0.09%) at 35 °C. Additionally, the smart window demonstrated long-term stability in dynamic transparent–opaque transitions and a low transition temperature of 30.9 °C. Therefore, the proposed composite presents several advantages, including high efficiency, low cost, and easy scalability, offering new insights into the design and fabrication of smart windows and other smart materials.

In this study, a series of high-performance polyimide (PI) films with low dielectric constant (D_k), ultralow dissipation factor (D_f), and low water absorption (W_A) are successfully developed through a dual-site molecular engineering strategy that couples steric hindrance with ester-linkage rigidity within the diamine framework. This synergistic design not only modulates intermolecular packing but also establishes a cooperative balance between backbone rigidity and free volume, enabling the simultaneous suppression of dielectric loss and moisture stability. Two aromatic ester-linkage diamines bearing phenyl and norbornyl side groups were synthesized and polymerized with three structurally distinct dianhydrides to systematically investigate their effects on the dielectric, thermal, and water absorption properties of the PIs. Experimental results unequivocally demonstrate that the combination of bulky norbornyl substituents and rigid ester-linkage PIs markedly restricts dipolar relaxation and suppresses intermolecular hydrogen bonding, leading to record-low D_f and W_A. In addition, a nonpolar and flexible alicyclic dimer diamine was incorporated to further enhance free volume and mechanical toughness while reducing the overall density of polarizable units. Among the resulting formulations, the optimal PI exhibits a highly balanced performance profile, achieving a low D_k (<3), ultralow D_f (<0.0020), high glass transition temperature (>350 °C), low coefficient of thermal expansion (25 ppm/°C), and excellent moisture resistance (W_A < 0.3%). Notably, the optimal PI simultaneously achieves the lowest D_k^1/2.D_f at 10 GHz and W_A values reported to date. These findings establish that the cooperative combination of steric hindrance, ester-linkage rigidity, and flexible hydrophobic diamine segments constitutes a powerful molecular design platform to overcome the conventional trade-off among dielectric loss, moisture resistance, and mechanical toughness, offering a promising platform for next-generation 5G and high-frequency electronic packaging applications.

Polymer network structures in epoxy thermosets play an important role in the final thermoset material properties. However, analytical characterization of these network structures is difficult due to their amorphous nature. In this work, the application of evolved gas analysis–mass spectrometry (EGA-MS) to characterize the polymer network structures of bisphenol A (BPA)-based thermosets is demonstrated. Analytical characterization of the polymer network structures is accomplished by monitoring the Product-Specific Kinetics (PSK) of BPA monomer formation during thermal degradation investigations. We relate observed differences in the activation energy (E_a) of BPA monomer formation to the local packing environment around the BPA monomer units within the polymer network. Variations in the local environment related to the polymer networks manifest qualitatively as broadening in the thermal profile of the BPA monomer evolution and quantitatively as changes in the activation energy (E_a). Three BPA thermoset formulations were investigated; two amine-cured thermoset with 4,4′-diaminodiphenylmethane (DDM) or poly(propylene glycol) bis(2-amino-propyl ether) (PPG400) and a homopolymerized thermoset via curing with Epikure 3253 catalyst (3253). Results revealed that the 3253 thermoset contained two distinct packing densities in the polymer network, while DDM and PPG400 thermosets had uniform distributions of packing densities. Results from the DDM thermoset revealed a gradually decreasing E_a, while the apparent E_a of PPG400 was consistent over the entire degradation. These differences in E_a were concluded to stem from the flexibility of the corresponding polymer networks and the ability of the network components to rearrange and occupy formed voids. Due to the minimal sample required for analysis (100–200 μg), this EGA-MS technique has great potential for postproduction evaluation of composite parts to identify changes in the polymer networks from use and aging, which could signal compromised performance.

Recycling plastic waste is crucial for reducing environmental harm and conserving resources. However, current methods face challenges, such as the need to sort different polymers, limited compatibility across plastic types, and reliance on hazardous chemicals in chemical recycling. This study introduces a sustainable additive manufacturing approach by repurposing commonly discarded thermoplastics, including polylactic acid (PLA), polyamide (PA), polypropylene (PP), polyethylene terephthalate (PET), and 3D-printed thermosets, as feedstock for digital light processing (DLP) 3D printing. Using cryogenic milling, these polymers are transformed into fine powders and incorporated into a photocurable resin to create polymeric composites. The addition of solid plastic particles presents two main challenges: increased resin viscosity and UV light blocking. These issues affect both printability and mechanical performance. To address viscosity, a heated vat system maintains the resin at ∼55 °C, improving flow without compromising the process. Additionally, UV light is blocked during photopolymerization, leading to incomplete curing and a 50% reduction in modulus compared to neat resin. A dual-curing approach mitigates this by combining UV-curing via a photoinitiator with thermal annealing via a thermal initiator, ensuring full polymerization and restoring mechanical strength. This strategy yields an ∼250% increase in modulus for high-loading samples, aligning with theoretical predictions. The study demonstrates broad applicability across various powder–resin combinations, highlighting its adaptability in diverse material contexts. Overall, this work establishes a pathway for incorporating a wide range of recycled plastics into high-performance 3D-printed composites, advancing both the sustainability and the functional potential of additive manufacturing.