The service life performance of timber products exposed to natural weathering is a critical factor limiting the broad use of wood as an external building element. The goal of this study was to ...investigate the in-service characterization of an innovative biofinish coating system. It is a novel surface finishing solution based on the bioinspired concept of living fungal cells designed for effective wood protection. The performance of Scots pine (Pinus sylvestris L.) wood coated with biofinish was compared with uncoated references. Samples were exposed to natural weathering for 12 months under the climatic conditions of northern Italy. The visual appearance, colour, gloss, wettability, and 3D surface topography of the wood surface were examined. Results revealed that the total colour changes (∆E) of biofinish-coated wood were negligible. Untreated Scots pine wood revealed the changes in colour after just three months of exposure. The gloss changes of both surface types were small. The contact angle measured on biofinish-coated wood was higher compared to that of uncoated Scots pine. Surface roughness increased in uncoated wood due to the erosion effect caused by the weathering progress. Conversely, the surface roughness of biofinish-coated samples decreased along the exposure time. This phenomenon was explained by two self-healing mechanisms: migration of non-polymerized oil to the cracked surface, where it polymerizes and creates a closed layer, and local regrowth to cover damaged spots by living fungal cells present in the coating. The obtained results revealed the superior aesthetic performance of the biofinish surface treatment against natural weathering. By considering the fully bio-based nature of the investigated coating, it was concluded that this solution can be an attractive alternative for state-of-the-art wood protection technologies.
This Special Issue of Coatings presents the newest research outcome in the field of the enhancement of native wood properties through a wide range of chemical, biological, and physical agents. The ...broad spectrum of topics provides a comprehensive update regarding ongoing research in this field. Such a compilation can be an inspiration for the further development of multifunctional and sustainable coatings, revolutionizing the wood sector of the future.
Incorporating reversible sacrificial bonds in network polymers not only toughens these materials but also endows them with self‐recoverability. However, self‐recoverability is only realized for ...dispersed energy less than 10 MJ m−3. It remains a challenge to achieve simultaneous high stretchability, toughness, and recoverability. Here, inspired by the structure of mussel byssus cuticles, a new design strategy is proposed and demonstrated to improve both the toughness and self‐recoverability of elastomers by introducing a microphase‐separated structure with different physical crosslink densities. This structure can be achieved using a carefully designed comonomer sequence distribution of hydrogen bonding units in an ABA‐type triblock copolymer. The A blocks form hard domains with dense crosslinking that prevents macroscopic deformation, while the B blocks form a softer matrix with sparse and dynamic crosslinks that serve as sacrificial bonds. This elastomer exhibits high toughness (≈62 MJ m−3), self‐healing, and most notably, excellent self‐recovery (recovery against 650% elongation and 17 MPa tensile stress with a dissipated energy >27 MJ m−3 at room temperature). This combination of toughness, self‐healing, and self‐recovery expands the range of applications of these advanced dynamic materials.
Polymers with toughness and excellent self‐recoverability are achieved by a bioinspired microphase‐separated structure with different physical crosslink densities. This structure is realized by a carefully designed comonomer sequence distribution of an ABA type triblock copolymer where the A and B blocks contain high and low amount of quadruple hydrogen‐bonding 2‐ureido‐41H‐pyrimidinone groups, respectively.
Improving the damage tolerance and reliability of ceramic artificial bone materials, such as sintered bodies of hydroxyapatite (HAp), that remain in vivo for long periods of time is of utmost ...importance. However, the intrinsic brittleness and low damage tolerance of ceramics make this challenging. This paper reports the synthesis of highly damage tolerant calcium phosphate-based materials with a bioinspired design for novel artificial bones. The heat treatment of isophthalate ion-containing octacalcium phosphate compacts in a nitrogen atmosphere at 1000°C for 24 h produced an HAp/β-tricalcium phosphate/pyrolytic carbon composite with a brick-and-mortar structure (similar to that of the nacreous layer). This composite exhibited excellent damage tolerance, with no brittle fracture upon nailing, likely attributable to the specific mechanical properties derived from its unique microstructure. Its maximum bending stress, maximum bending strain, Young’s modulus, and Vickers hardness were 11.7 MPa, 2.8 × 10‒2, 5.3 GPa, and 11.7 kgf/mm2, respectively. The material exhibited a lower Young’s modulus and higher fracture strain than that of HAp-sintered bodies and sintered-body samples prepared from pure octacalcium phosphate compacts. Additionally, the apatite-forming ability of the obtained material was confirmed in vitro, using a simulated body fluid. The proposed bioinspired material design could enable the fabrication of highly damage tolerant artificial bones that remain in vivo for long durations of time.
Diblock copolymers consisting of a homopolymer of a amide functionalized norbornene, PA, and a random copolymer of a flexible dodecanyl norbornene and A, P(D-r-A), were prepared and characterized. ...These block copolymers showed higher toughness than those of simple block copolymers, PD-b-PA, and random copolymers, P(D-r-A). The toughening is attributed to the microphase separated structure composed of spherical domains of PA blocks with dense hydrogen bonds surrounded by a soft matrix of P(D-r-A) block. The sparse hydrogen bonds in the matrix act as dynamic crosslinks, serving as sacrificial bonds to toughen the polymer. Self-healing ability was also confirmed in this copolymer.
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