Self-assembled monolayers of partially fluorinated alcohols on Si(001): XPS and UV-photoemission study

Understanding changes in holocellulose and lignin compounds in wooden structure of veneers: Molecular insights post hydrothermal treatment and aging

Veneers obtained via hydrothermal treatment serve to enhance the aesthetic appeal of furniture and other wooden surfaces. However, the impact of this treatment on the chemical composition of holocellulose and lignin, coupled with their resistance to ultraviolet (UV) irradiation, remains a relatively unexplored area requiring further investigation. In the experiment, wood samples of three distinct species underwent hydrothermal treatment followed by exposure to UV aging. Parameters including colour, contact angle, and acid-base properties were examined alongside their chemical alterations during these processes. These observed properties were then correlated with changes identified through FT-IR and Py-GC/MS analyses to uncover their molecular origins. Through these methods, the study offered insights into the chemical transformations driving the observed alterations. Findings revealed the considerable impact of hydrothermal treatment on these properties and their propensity for modification under UV radiation. In most test variations, hydrothermal treatment amplified tendencies toward colour changes, increased hydrophobicity, and basicity. Analysis of chemical changes suggested the degradation of polysaccharides due to hydrothermal treatment and lignin breakdown under UV irradiation. Understanding these molecular changes provides a foundation for mitigating the adverse effects of hydrothermal wood treatment.

Solution Chemistry to Control Boron-Containing Monolayers on Silicon: Reactions of Boric Acid and 4-Fluorophenylboronic Acid with H- and Cl-terminated Si(100)

The reactions of boric acid and 4-fluorophenylboronic acid with H- and Cl-terminated Si(100) surfaces in solution were investigated. X-ray photoelectron spectroscopy (XPS) studies reveal that both molecules react preferentially with Cl-Si(100) and not with H-Si(100) at identical conditions. On Cl-Si(100), the reactions introduce boron onto the surface, forming a Si-O-B structure. The quantification of boron surface coverage demonstrates that the 4-fluorophenylboronic acid leads to ∼2.8 times higher boron coverage compared to that of boric acid on Cl-Si(100). Consistent with these observations, density functional theory studies show that the reaction of boric acid and 4-fluorophenylboronic acid is more favorable with the Cl- versus H-terminated surface and that on Cl-Si(100) the reaction with 4-fluorophenylboronic acid is ∼55.3 kJ/mol more thermodynamically favorable than the reaction with boric acid. The computational studies were also used to demonstrate the propensity of the overall approach to form high-coverage monolayers on these surfaces, with implications for selective-area boron-based monolayer doping.