ACS Applied Polymer Materials最新文献

Rewritable papers based on switchable molecules have attracted much attention for different applications. The performance of hydrochromic rewritable papers is very important in terms of being environmentally friendly and nontoxic. In this study, azobenzene compounds with two different hydroxyl and carboxylic acid functionalities were doped on poly(methyl methacrylate) (PMMA) and poly(methyl methacrylate-co-glycidyl methacrylate) (PMMA-GMA) particles prepared by one-step emulsifier-free emulsion polymerization. Ultraviolet–visible (UV–vis) spectra of the AZO1 in CH₃CN solution at 560 nm are more bathochromic than the absorption peak of AZO2 at 515 nm. By adding water to AZO1, a new peak at 410 nm is observed with a color change from purple to yellow, which is the result of the formation of the hydrochromic form. In AZO2, the hydrochromic absorption wavelength is 445 nm with a color change from pink to yellow/orange. The difference in absorption wavelengths of the two stable and hydrochromic states of AZO1 and AZO2 is 150 and 70 nm, respectively. The hydrochromic rewritable papers were prepared by physical incorporation of azobenzene-containing polymer particles on cellulosic papers. The samples containing PMMA particles go through the pattern with more clarity, more vivid color, faster return, and erasing. The sample containing hydroxyl-functional azobenzene is more suitable for rewritable papers due to the presence of donating exochromic group and providing more clear patterns from fingerprints, handwriting, and stamping. The rewritable papers showed applicability in 10 cycles of writing by water and changing the color from purple to yellow and back during the time and water evaporation. These rewritable papers were used in human sweat pore mapping applications, security marking of different documents, camouflage, and also indication of latent fingerprints, diapers wetting, and fever. Such hydrochromic rewritable papers are highly important in sustainability insights and also reducing the huge consumption of cellulosic papers produced from natural resources.

Covalent organic frameworks (COFs) are considered optimal candidates for third-order nonlinear optical (NLO) materials due to their extended conjugation networks and structural tunability. Nevertheless, the comprehension of the NLO response mechanism in donor–acceptor (D–A) type COFs, particularly the augmentation of the conjugation degree of the donor or acceptor unit, remains inadequate. Accordingly, in the present study, a D–A type COF, BT-COF1, was constructed utilizing triphenylamine as an electron donor; BT-COF2 and BT-COF3 were synthesized by increasing the π-conjugation degree of the donor and acceptor units in BT-COF1. The NLO properties of these materials were investigated using Z-scan techniques. Results reveal that all three BT-COFs exhibit saturable absorption and self-focusing effects, with β values of −9.31 × 10^–7 m/W for BT-COF1, −8.19 × 10^–7 m/W for BT-COF2, and −4.3 × 10^–6 m/W for BT-COF3. In comparison to BT-COF1, the augmented donor conjugation in BT-COF2 results in a widening of the band gap and a decline in the NLO performance. Conversely, the augmented acceptor conjugation in BT-COF3 results in a narrower band gap and an enhanced NLO performance. This may be attributed to the fact that the enhanced π-conjugation of the acceptor unit is more conducive to intramolecular charge transfer in BT-COFs than that of the donor unit. This study presents a theoretical framework for elucidating the relationship between the structural design of COF materials and their NLO properties, as well as providing guidance for the design of COFs with optimal NLO performance.

Injectable hydrogels provide enhanced targeting capabilities, and their minimally invasive administration makes them promising drug carriers. However, concerns related to biodegradability and biocompatibility may restrict their effectiveness. To overcome these limitations, a pH-responsive, injectable, shear-thinning hydrogel has been developed using modified carboxymethyl cellulose (m-CMC) and modified chitosan (m-CS). The hydrogel has been synthesized by cross-linking the amine groups of m-CS with the aldehyde groups of m-CMC. The resultant hydrogel exhibits rapid gelation within 60 s at physiological temperature and forms a dynamic network through Schiff base and electrostatic interactions, enabling shear-thinning behavior. The incorporation of m-CMC and m-CS into the hydrogel backbone enhances biocompatibility, hemocompatibility, biodegradability, and antioxidant properties. The ease of injectability allows for minimally invasive administration and prolonged drug retention at the target site, thereby improving the efficiency of site-specific drug delivery. Additionally, the hydrogel exhibits potential antibacterial characteristics against Gram-negative (E. coli) and Gram-positive (S. aureus) bacteria. The pH-responsive nature of the m-CMC/m-CS hydrogel enables the controlled release of a model drug (diclofenac sodium, DS) at the target site under physiological conditions, thereby improving therapeutic efficacy.

In this work, a triple-shape memory polymer was developed by solution blending of poly(lactic acid) (PLA) with poly(propylene carbonate) (PPC), which was 3D printed using the material extrusion principle. The blend of crystalline PLA and amorphous PPC enabled it to attain tunable mechanical properties. Morphological observations of blended PLA/PPC samples revealed a phase-segregated morphology, resulting in the appearance of two distinct glass transition temperatures, exhibiting a triple-shape memory effect (triple-SME). The PLA50/PPC50 composition achieved an optimum shape-fixity ratio (95.63%) and shape-recovery ratio (96.26%) due to the existence of a cocontinuous phase morphology. As a proof of concept, 4D printing of the PLA50/PPC50 composition was demonstrated at body temperature as a potential biomedical application to facilitate minimally invasive surgery. The in vitro degradation study of the PLA50/PPC50 composition resulted in a 7.5% mass loss over a period of 56 days. Finally, the in vitro cytotoxicity of all 3D printed PLA/PPC blends demonstrated excellent biocompatibility, proving their potential as an implant for tissue engineering applications. The elucidation of the parameters influencing the selective actuation of triple-SME gained from this study is expected to open a wide range of possibilities for use in biomedical devices.

Hierarchical and topographical surface structures are abundant in nature, from the beetle carapace to plant leaves. The interactions between hierarchically structured, natural surfaces and water continue to inspire researchers; these natural designs have been translated to engineering strategies for antifogging coatings and membrane filtration processes. In this work, photoinduced phase separation (PIPS) is utilized to generate naturally inspired hierarchical topographical features on polymer surfaces in a single-step procedure. These complex designs are accessible when a polymer coating undergoes PIPS since both the classic surface wrinkling phenomenon, facilitated by oxygen quenching of radicals, as well as additional patterning from the phase-separated morphology yield topographies on multiple length scales. We demonstrate this patterning in a photopolymerizable resin system composed of acrylonitrile and 1,6-hexanediol diacrylate (co)monomers with poly(methyl methacrylate) as an inert polymer additive. A wide range of surface features arise from this resin system, which were characterized via imaging and optical profilometry. Furthermore, the topographies that formed were mapped to resin formulation parameters (e.g., cross-linking fraction, inert polymer loading) and experimental conditions (e.g., UV intensity). Our analysis highlights how diffusional constraints vary based on cross-link density and thus impact the scale and quality of topography that forms during polymerization. Increased cross-linker loading results in a kinetically trapped system, where the rapid network formation inhibits surface relaxations. Conversely, with decreased cross-linking, mechanical gradients due to radical quenching can evolve, and when PIPS arises simultaneously multiple scales of patterning form on a single surface, spanning from the micro to macroscale. By linking the observed kinetics with the final surface morphologies, we detail how PIPS can be utilized in tandem with traditional wrinkling to tailor hierarchical surface morphologies in rapid, ambient photopolymerizations for the facile production of tunable coating topographies.

Toxic metal ion pollution poses significant risks to ecosystems and human health, necessitating effective remediating strategies. Various methods have been developed for the removal of metal ions from the environment. However, the existing methods for metal ion removal are often complex and do not ensure retrieval of the removed ions or reusability of the retrieving material. In this work, we show the preparation of a methacrylate spiropyran-functionalized polydimethylsiloxane sponge (PDMS-SP) to capture metal ions from the environment. The photoresponsive SP content of the samples is about 0.23%, endowing these materials with the unique feature of reversible complexation that can be remotely modulated by light. Spiropyran can reversibly isomerize to merocyanine in these sponges; the latter isomer can make complexes with some toxic cations: Al³⁺, Zn²⁺, Fe³⁺, Co²⁺, Sn²⁺, and Hg²⁺. The sponges can also complex with Ca²⁺ and Mg²⁺. UV–vis spectroscopy was used to calculate the complexation yields and adsorption capacity. As an example, the Fe³⁺ adsorption capacity of the PDMS-SP sponge was calculated as 2.60 ± 0.15 mg g^–1. We also demonstrate that the ions can easily be retrieved from the ion-adsorbed sponge by rinsing the sponge with a solvent under visible light. The sponges can be reused for at least 5 cycles without fatigue, mechanical deformation, or significant loss of adsorbent activity.

Although poly(butylene adipate-co-terephthalate) (PBAT) is a biodegradable polymer with exceptional flexibility, its broader applications are constrained by insufficient heat resistance and suboptimal mechanical qualities. To address these limitations, we used in situ fibrillation and supercritical CO₂ to developed PBAT/sc-PLA composite foams with enhanced antishrinkage and heat resistance by incorporating biodegradable stereocomplexed polylactide (sc-PLA) with complementary properties. The experimental results demonstrated that the synergistic effect of sc-PLA and in situ fibrillation significantly enhanced the crystallinity, mechanical properties and heat resistance of the composites. Specifically, the in situ fibrillated composite 30LD-F exhibited a total crystallinity of 41.23%, a yield strength improvement of 128.38%, and a Vicat softening temperature of 99.8 °C. Furthermore, the 30LD-F foam displayed excellent antishrinkage with a low volumetric shrinkage of 0.39% and a heat-induced shrinkage of 29.46%. This study demonstrates that in situ fibrillated PBAT/sc-PLA composites are promising for high-performance applications requiring heat resistance and mechanical strength, such as automotive components and heat-resistant packaging.

Designing thermoset materials with dynamic cross-links is an important strategy to mitigate rising global carbon dioxide emission levels. The development of polymers from sustainable feedstocks, with efficient manufacturing methods, for high-value applications, and with circular end-of-use solutions is essential for advancing material technologies. One approach involves exploiting carbon dioxide itself as a feedstock to create high-performance, sustainable materials by enchaining 50 mol % CO₂ via copolymerization with epoxides to yield polycarbonates. This work describes the synthesis, end-functionalization, and curing of poly(propylene carbonate) (PPC) and poly(cyclohexene carbonate) (PCHC) into β-hydroxy ester vitrimers. These vitrimers demonstrate the ability to be mechanically reprocessed up to 3 times with retention of the material’s properties through dynamic transesterification exchange reactions. The polycarbonate vitrimers with gel fractions exceeding 90% exhibit high tensile strength (>50 MPa) and Young’s modulus (>2 GPa), achieved by varying the repeat unit structure in the polymer backbone from the low T_g PPC to the more rigid high T_g PCHC structures. Owing to an entropically favorable chain backbiting mechanism, the network chains can be cleaved and depolymerized into cyclic small molecules. In the case of PCHC, this process enables repolymerization back to polycarbonates with 69 wt % CO₂ retention through life cycles. The promising mechanical performance and recyclability of these CO₂-based polycarbonate vitrimers indicate their potential for sustainable, high-performance materials, paving the way for future innovations in circular polymer technologies and carbon capture utilization.

As a thermosetting resin, hydantoin epoxy resin can acquire shape memory functionality and reprocessability through the incorporation of a reversible cross-linking network. However, its practical application is constrained by inherent limitations, including sluggish reaction kinetics, inadequate thermal resistance, and suboptimal mechanical strength. To address these challenges, we synthesized a modifier bismaleimide-diamino diphenyl sulfone (BMDS) through the reaction between bismaleimide and 4,4′-diamino diphenyl sulfone. The amine groups in BMDS effectively accelerated the curing process by reducing the reaction activation energy from 69.74 to 67.14 kJ/mol. Remarkably, BMDS modification enhanced the thermal stability of the resin system, elevating its heat resistance index from 174.26 to 179.99 °C and increasing the char yield from 13.39% to 18.21%. Concurrently, mechanical properties showed substantial improvement, with tensile strength rising from 37.2 to 64.7 MPa and flexural strength from 69.9 to 94.8 MPa. Crucially, these enhancements were achieved while preserving the material’s intrinsic shape memory behavior and secondary processability. Furthermore, solvent-recovered BMDS-modified resin demonstrated successful structural reconstruction through secondary curing, facilitated by its dynamic reversible cross-linking network. This approach not only enables efficient material recycling but also maintains shape memory functionality, presenting a viable strategy for developing sustainable thermosetting polymers.

Hydrogel materials containing gelatin can improve the biocompatibility and biodegradability of sensing materials, so they can be widely used in flexible sensors, health monitoring, and smart electronic devices. In this paper, using gelatin as a biomass-based material, the interpenetrating network structure formed between gelatin and polyacrylamide could not only improve the strong stretchability and flexibility of hydrogel but also provide more binding sites for conductive materials. Then, the polyacrylamide–gelatin MXene hydrogel (PGMH) sensor with excellent sensing performance and tensile strength was prepared by introducing MXene into the polyacrylamide–gelatin network structure. In addition to enhancing the mechanical properties of the hydrogel, the electrical conductivity and sensing properties are effectively improved as a wearable electronic device; the breathability of the hydrogel sensing material can ensure its adequate wear safety and comfort. Importantly, its biomass-based feedstock also gives it excellent stability and comfort to use. The designed hydrogel sensor has good stability and wide applicability and has great application potential in the next generation of degradable wearable electronic devices.