In this review, we provide an overview of how atomic force microscopy (AFM) measurements on wood or other plant fibers help us understand the structure-property relationship in growing plants, matured wood material, and wood modifications and aging. We selected wood as a model material that can represent a number of lignocellulosic systems and attempted to address the structure-property relationship, as studied in situ. We selected AFM because it allows scientists to study materials in an unaltered, in situ form and relate chemical composition to material properties at a nanoscale level. We summarized the high-resolution measurements of wood cell walls such as topography, adhesion force, modulus, and chemical functional groups using AFM. Our three focus areas were: (1) how the cell wall develops its structure and property in living trees; (2) how the ultrastructure determines cell wall property; and (3) how the modification/aging of the cell wall changes its property in application scenarios.

Wood is the most important, industrially used renewable resource on the planet, but the aging mechanism of biopolymers on cell walls is poorly understood. Adhesion properties are of critical importance for wood and many other lignocellulosic materials. We used atomic force microscopy and defined the jump-off force ratio in the retract force–displacement curve to study the adhesion force phenomenon and the effects of heat treatments. Here, we identified two sigmoidal curves describing the shift of the adhesion force and the jump-off force ratio: the first curve was attributed to the movement of extractives and the second to the degradation of the hemicellulose–lignin matrix. We confirmed the hypothesis formulated in this paper by the cell wall surface topography, the analysis of the treated samples by Fourier transform infrared spectroscopy, and the analysis of volatiles during heating by headspace gas chromatography-mass spectrometry.

This study aims to measure the pit torus and border to monitor the immediate and short-term degradation of wood surfaces after the concrete is cast and the cement hydration releases heat. The surface morphology and adhesion force curves were measured by atomic force microscopy during the treatments in saturated calcium hydroxide solutions ranging from 1 h to 27 days. The results showed that the pit torus and pit border showed different degradation processes. The adhesion force was sensitive to the type of the surface chemical components exposed during the degradation, while the surface modulus, deformation and jump-off force ratio were sensitive to the surface structural strength. The surface modulus of the pit torus degraded to 0.61–0.66 of the untreated original (95% CI) after 7-h treatments, and degraded almost completely after 48-h treatments. The surface modulus of the pit border degraded to 0.83–0.95 of the untreated original (CI) after 10 days and to 0.20–0.23 of the untreated original (95% CI) after 27 days of treatments. The treatment temperature 50 °C caused a 10-times faster degradation in the torus modulus compared to the temperature 20 °C.

As a powerful tool to investigate the surface properties at a nano-scale resolution, the atomic force microscopy (AFM) encounters challenges in the measurement of plant materials such as wood surface. In particular, for rough and heterogeneous surfaces, a robust and easily performed positioning method is necessary for reproducible measurements. One of the critical issues is the ability to position the AFM tip after the specimens are removed for treatments from a device and repeatedly analyzed. If the tip is not repeatably positioned within the measured area, the natural variability of surface (such as surface roughness) can mask the effects of treatments of interest. In this paper, a positioning method using the bordered pit of the wood radial surface as a natural marker is proposed and a systematic measurement procedure is presented. The idea results from the uniqueness of the anatomical features of a natural material (wood in this case) and low probability of having exactly the same geometry of pit clusters in the vicinity of the area of interest. The results show that the anatomical features can be used as unique markers for precise positioning of the AFM tip. The process is demonstrated using an example of the effect of temperature on adhesion forces on the wood surface. After the heat treatment, the wood surface layers were investigated with Fourier transform infrared spectroscopy and attenuated total reflection (FTIR-ATR).

This study presents an innovative solution to improve the mechanical performance of traditional cemented tailings backfill (CTB) by incorporating 3D-printed polymer lattice (3DPPL) reinforcements. We systematically investigated three distinct 3DPPL configurations (four-column FC, six-column SC, and cross-shaped CO) through comprehensive experimental methods including Brazilian splitting tests, digital image correlation (DIC), and scanning electron microscopy (SEM). The results show that the 3DPPL reinforcement significantly enhances the CTB’s tensile properties, with the CO structure demonstrating the most substantial improvement—increasing the tensile strength by 85.6% (to 0.386 MPa) at a cement-to-tailings ratio of 1:8. The 3DPPL-modified CTB exhibited superior ductility and progressive failure characteristics, as evidenced by multi-stage load-deflection behavior and a significantly higher strain capacity (41.698–51.765%) compared to unreinforced specimens (2.504–4.841%). The reinforcement mechanism involved synergistic effects of macroscopic truss behavior and microscopic interfacial bonding, which effectively redistributed the stress and dissipated energy. This multi-scale approach successfully transforms CTB’s failure mode from brittle to progressive while optimizing both strength and toughness, providing a promising advancement for mine backfill material design.