Chinese Journal of Polymer Science最新文献

Hydrogen bonds (H-bonds) are the most essential non-covalent interactions in nature, playing a crucial role in stabilizing the secondary structures of proteins. Taking inspiration from nature, researchers have developed several multiple H-bonds crosslinked supramolecular polymer materials through the incorporation of H-bond side-chain units into the polymer chains. N-acryloyl glycinamide (NAGA) is a monomer with dual amides in the side group, which facilitates the formation of multiple dense intermolecular H-bonds within poly(N-acryloyl glycinamide) (PNAGA), thereby exhibiting diverse properties dependent on concentration and meeting various requirements across different applications. Moreover, numerous attempts have been undertaken to synthesize diverse NAGA-derived units through meticulous chemical structure regulation and fabricate corresponding H-bonding crosslinked supramolecular polymer materials. Despite this, the systematic clarification of the impact of chemical structures of side moieties on intermolecular associations and material performances remains lacking. The present review will focus on the design principle for synthesizing NAGA-derived H-bond side-chain units and provide an overview of the recent advancements in multiple H-bonds crosslinked PNAGA-derived supramolecular polymer materials, which can be categorized into three groups based on the chemical structure of H-bonds units: (1) monomers with solely cooperative H-bonds; (2) monomers with synergistic H-bonds and other physical interactions; and (3) diol chain extenders with cooperative H-bonds. The significance of subtle structural variations in these NAGA-derived units, enabling the fabrication of hydrogen-bonded supramolecular polymer materials with significantly diverse performances, will be emphasized. Moreover, the extensive applications of multiple H-bonds crosslinked supramolecular polymer materials will be elucidated.

Nowadays organosilicon luminescent materials are of increasing interest due to the variety of their synthetic or modification techniques and application fields. Ladder polyphenylsilsesquioxanes (L-PPSQ) are a unique class of organosilicon polymers, which can be ideal matrices for the luminescent composites due to their high thermal stability, optical transparency and mechanical strength. In this work, new mechanically strong, heat-resistant, transparent and sensitive to ammonia vapor luminescent composite films based on L-PPSQ have been obtained. As the source of Europium ions oligophenyleuropiumsiloxane was used, demonstrating perfect compatibility to the matrix due to the similar nature. To improve luminescent properties of the films, new organosilicon ligands were introduced into the composites and their influence on the properties of the materials was studied. Valuable properties of described composites may allow their further application as multifunctional coatings.

Developing hydroscopic actuators with simultaneous high elasticity, shape programmability and tunable actuating behaviors are highly desired but still challenging. In this study, we propose an orthogonal composite design to develop such a material. The developed composite elastomer comprises carboxyl group-grafted polystyrene-block-poly(ethylene-co-butylene)-block-polystyrene (SEBS-g-COOH) as the elastic substrate, and a synthesized azobenzene derivative as the functional filler (Azo12). By surface treatment using acidic and base solutions, the carboxyl groups on the surface can reversibly transform into carboxylate groups, which render the composite tunable hygroscopic actuating functionality. On another aspect, the added filler undergoes trans-to-cis isomerization when exposed to UV light irradiation, leading to liquefaction of the crystalline aggregates formed by Azo12 molecules. The liquefied Azo12 molecules can autonomously resotre their trans form and reform the crystalline structure. This reversible change in crystralline structure is utilized to realize the shape memory property, and 5 wt% of Azo12 addition is adequate for the composite to exhibit photo-responsive shape memory behavior without compromising much of the elasricity. The regualtion of external geometry by shape memory effect is effective in altering the actuating behavior. The proposed method can be extend to designing different composites with the demonstrated functionalities.

In this study, we synthesized a series of ABA-type vitrimers by crosslinking the short A moieties of precursors with a bifunctional crosslinker and evaporating the small molecular byproduct. The vitrimer samples thus prepared exhibit linear viscoelasticity dependent on the length of A moiety as well as the content of the crosslinks. When the average number of A monomers per end moiety m=1.1, the crosslinker can only extend the chain but not crosslink the chain. When m becomes 2.8 or higher, introducing a crosslinker first leads to the gelation, whereas excess in crosslinker molecules leads opening of the crosslinking sites and accordingly reentry into the sol regime. Surprisingly, a further increase in the length of the A moieties increases the relaxation time much weaker than the exponential increase seen for the physically crosslinked ABA-type ionomers. We attribute this difference to the distinct relaxation mechanisms: the relaxation of the vitrimer samples is based on relatively independent exchange reactions, which contrasts with the ABA-type ionomers that relax through the collective hopping of connected ionic groups from one ion aggregate to another.

Polyimides are a family of high-tech plastics that have irreplaceable applications in the fields of aerospace, defense, and opto-electronics, but polyimides are difficult to be reprocessed and recycled at the end of their service life, resulting in a significant waste of resources. Hence, it is of great significance to develop recyclable polyimides with comparable properties to the commercial products. Herein, we report a novel polymer-to-monomers chemically recyclable poly(imide-imine) (PtM-CR-PII) plastic, synthesized by cross-linking the amine-terminated aromatic bisimide monomer and the hexa-vanillin terminated cyclophosphazene monomer via dynamic imine bonds. The PtM-CR-PII plastic exhibits comparable mechanical and thermal properties as well as chemical stability to the commercial polyimides. The PtM-CR-PII plastic possesses a high Young’s modulus of ≈3.2 GPa and a tensile strength as high as ≈108 MPa, which also exhibits high thermal stability with a glass transition temperature of ≈220 °C. Moreover, the PtM-CR-PII plastic exhibits outstanding waterproofness, acid/alkali-resistance, and solvent-resistance, its appearance and mechanical properties can be well maintained after long-term soaking in water, highly concentrated acid and base, and various organic solvents. Furthermore, the cyclophosphazene moieties endow the PtM-CR-PII plastic with excellent flame retardancy. The PtM-CR-PII plastic exhibits the highest UL-94 flame-retarding rating of V-0 and a limiting oxygen index (LOI) value of 45.5%. Importantly, the PtM-CR-PII plastic can be depolymerized in an organic solvents-acid mixture medium at room temperature, allowing easy separation and recovery of both monomers in high purity. The recovered pure monomers can be used to regenerate new PtM-CR-PII plastics, enabling sustainable polymer-monomers-polymer circulation.

Polydimethylsiloxane (PDMS) is an electron-withdrawing material that is widely used in triboelectric nanogenerators (TENGs). However, PDMS has poor mechanical properties after curing and is easily damaged when subjected to long-term workloads. Thus, the long-term stable operation of TENGs under mechanical deformation cannot be guaranteed. In this work, multiple hydrogen bonds and aromatic disulfide bonds were introduced into PDMS elastomers. These elastomers exhibited high toughness (a tensile strength of 1.91 MPa and an elongation at break of 340%), good recyclability, and room-temperature self-healing properties (healing efficiency of 96.4% in 24 h). Recyclable sandwich-like triboelectric nanogenerators with excellent electrical output performance (13.5 V) and room-temperature self-healing performance (24 h, 98% recovery of self-generating performance) were prepared by utilizing the hydrogen bonding between the PDMS elastomer and MXene. The work reported herein offers theoretical guidance and a compelling strategy for developing high-performance TENG negative friction layers.

The development of physically crosslinked hydrogels with excellent mechanical and sensing properties is of importance for expanding the practical applications of intelligent soft hydrogel materials. Herein, after copolymerization of hydroxyl-containing amino acid derivative N-acryloyl serine (ASer) with acrylamide (AM), we introduce Zr⁴⁺ through an immersion strategy to construct metal ion-toughened non-covalent crosslinked hydrogels (with tensile strength of up to 5.73 MPa). It is found that the synergistic coordination of hydroxyl and carboxyl groups with Zr⁴⁺ substantially increases the crosslinking density of the hydrogels, thereby imparting markedly superior mechanical properties compared to hydroxyl-free Zr⁴⁺-crosslinked hydrogels, such as N-acryloyl alanine (AAla) copolymerized with AM hydrogels (with tensile strength of 2.98 MPa). Through the adjustment of the composition of the copolymer and the density of coordination bonds, the mechanical properties of the hydrogels can be modulated over a wide range. Additionally, due to the introduction of metal ions and the dynamic nature of coordination bonds, the hydrogels also exhibit excellent sensing performance and good self-recovery properties, paving the way for the development of flexible electronic substrates with outstanding comprehensive performances.

Crystal polymers or liquid crystal elastomers undergo a phase transition that results in a change in the corresponding optical properties, which has the potential to be applied in areas such as information encryption and anti-counterfeiting. The utilization of these materials for patterning purposes requires different phase transition temperatures. However, once prepared, altering the phase transition temperature of them presents significant challenges. Herein, a poly(oxime-ester) (POE) network is developed to achieve high-resolution and multilevel patterning by photo-induced isomerization. The as-prepared POE exhibits the ability to transition from an opaque state to a transparent state under temperature stimuli, with the transition temperature and kinetics dependent on UV light exposure time. Thus, complex patterns and information can be encrypted through different selective regional exposure time and decrypted under specific temperature or cooling time. Furthermore, we illustrate an example of temporal communication, where cooling time or temperature serves as the encoded information. This research expands the application scope of advanced encryption materials, showcasing the potential of POE in dynamic information encryption and decryption processes.

Adhesives play an important role in modern society’s production and daily life. Developing robust and sustainable adhesives remains a great challenge. Here we report a sustainable epoxy-vitrimer adhesive with high adhesive strength (about 10 MPa) and reusability (82% strength after 3 times). This adhesive can be fabricated from commercially available products through a straightforward hot-pressing method without the need of solvents. The adhesive process is also simple, requiring only 30 min at 180 °C. In addition, the vitrimer adhesive has the advantages of both erasability for reuse and excellent water resistance. This work provides a facile strategy to fabricate high-strength adhesive that ensures reusability, recyclability, low cost of raw materials, and simple processing technology. Simultaneously, it expands the range of potential applications for epoxy vitrimers.