An evaluation model to predict microplastics generation from polystyrene foams and experimental verification.

Microplastics (MPs) have caused global concerns due to their detrimental effects on ecosystems and even humans. Recycling aged plastic products ahead of MPs generation can be an effective approach to mitigate increasingly serious microplastic pollution. However, predicting MPs generation remains a great challenge. In this regard, we report a simulation method through associating plastics aging with mechanical failure on a time scale to predict MPs generation and give an experimental verification. The results indicate that the proposed evaluation method has high accuracy for predicting MPs generation from aged polystyrene foams. Under conditions of ultraviolet (UV) irradiation and heat for 1000 h, the aged polystyrene foam generate significant microplastics (6.78 × 106 particles/cm3) by water scouring force after the expected aging time (400 h). Furthermore, the experiment results verify the synergistic effect of UV irradiation and heat on polystyrene MPs generation. This work suggests a new strategy to predict MPs generation from aged plastics in complex environments, which provides meaningful guidance for the use and recycling of plastic products.

Mechano-Regulable and Healable Silk-Based Materials for Adaptive Applications.

Mechanically adaptive materials responsive to environmental stimuli through changing mechanical properties are highly attractive in intelligent devices. However, it is hard to regulate the mechanical properties of most mechanically adaptive materials in a facile way. Moreover, it remains a challenge to achieve mechano-regulable materials with mechanical properties ranging from high strength to extreme toughness. Here, inspired by the reversible nanofibril network structure of skeletal muscle to achieve muscle strength regulation, we present a mechano-regulable biopolymeric silk fibroin (SF) composite through regulating dynamic metal-ligand coordination bonds by using water molecules as competitive regulators. Efficient interfacial hydrogen bonds between tannic acid-tungsten disulfide nanohybrids and the SF matrix endow the composite with high mechanical strength and self-healing ability. The resulting composite exhibits 837-fold change in Young's modulus (5.77 ± 0.61 GPa to 6.89 ± 0.64 MPa) after water vapor triggering, high mechanical properties (72.5 ± 6.3 MPa), and excellent self-healing efficiency (nearly 100%). The proof-of-concept ultraconformable iontronic skin and smart actuators are demonstrated, thereby providing a direction for future self-adaptive smart device applications.

Strong, Healable, Stimulus-Responsive Fluorescent Elastomers Based on Assembled Borate Dynamic Nanostructures.

Self-healing materials integrated with robust mechanical property and fascinating functions synchronously hold great prospects in many applications, but it still remains a grand challenge. Here, a bottom-up assembly method of preparing borate dynamic nanostructures (BDN) with controllable morphologies and interfacial crosslinks is proposed, from which a robust self-healing elastomer is fabricated. The BDN is optimized to construct dense and strong interfacial boronic easter crosslinks, endowing the elastomer with outstanding stretchability (2050%), high strength (17.9 MPa) as well as healing efficiency (77.1%). Moreover, the elastomer also exhibits pH stimulus-responsive fluorescence property and excellent functional repairability, enabling its potential application in intelligent material fields such as information encoding and encryption. This study demonstrates a general approach to produce self-healable functional materials with robust mechanical properties, and defines a rich platform for exploring various functional nanostructured materials.

Wood-Derived Hybrid Scaffold with Highly Anisotropic Features on Mechanics and Liquid Transport toward Cell Migration and Alignment.

Fantastic structures in nature have inspired much incredible research. Wood, a typical model of anisotropy and hierarchy, has been widely investigated for its mechanical properties and water extraction abilities, although applications in biological areas remain challenging. Delignified wood composite with in situ deposited hydroxyapatite (HAp) and infiltrated polycaprolactone (PCL) is hereby fabricated in an attempt to mimic natural bone. The inherent structure and properties of wood are carefully preserved during the fabrication, showing anisotropic mechanical properties in the radial direction (420 MPa) and longitudinal direction (20 MPa). In addition, it also performs directional liquid transport, effectively inducing the migration and alignment of cells to simulate the uniform seeding behavior of various cells in natural bone. Moreover, the synergistic effect of blended HAp and PCL largely promotes cell proliferation and osteogenic differentiation, providing a promising candidate for bone regeneration materials.