Adsorption of Polyetheramine-230 on Expansive Clay and Structure Properties Investigation

Polyetheramine (PEA) is a swelling inhibitor used to address engineering challenges arising from the interaction between montmorillonite (Mt) and water. This study comprehensively investigates the adsorption characteristics of PEA on three representative expansive clay samples: Na-Mt, Ca-Mt, and engineered expansive soil. Additionally, the desorption of exchangeable ions is examined. The findings reveal that a two-stage adsorption kinetic model and a pseudo-second-order kinetic model can properly describe the adsorption kinetics of PEA on expansive clays. PEA exhibits a strong capacity for ion exchange with sodium ions, while the exchange capacity for calcium ions is limited. Both protonated and non-protonated PEA contribute to rapid adsorption processes. The adsorption isotherms are well-fitted by the Langmuir and Freundlich models, with the Langmuir model being reasonable. At lower equilibrium concentrations, a higher proportion of the adsorption amount is attributed to ion exchange compared to higher equilibrium concentrations. Ion exchange emerges as the primary factor contributing to the adsorption of PEA on Na-Mt, whereas the adsorption of PEA on Ca-Mt and expansive soil is primarily attributed to physical adsorption by non-protonated PEA. X-ray diffraction results reveal significant intercalation effects of PEA as they penetrate the interlayer space and hinder interlayer ion hydration. Fourier transform infrared spectrum results demonstrate that the adsorption of PEA minimally impacts the framework of Mt structural units but primarily reduces the adsorbed water content. Clay-PEA composites exhibit a decreased affinity for water. Zeta potential experiments indicate that the adsorption of PEA significantly diminishes the surface potential of clay-PEA composite particles, effectively inhibiting their hydration dispersion.

Strong, Reusable, and Self-Healing Lignin-Containing Polyurea Adhesives

Reusable, self-healable, removable, and strong bio-based polyurea adhesives were successfully synthesized via partially substituting polyetheramine with polyetheramine-grafted lignin and introducing a chain extender containing dynamic disulfide bonds. The polyetheramine-grafted lignin endowed the polyurea adhesives with significantly enhanced adhesion strength on either metal or wood substrates by introducing intensive hydrogen bonding interactions; the dynamic disulfide bonds played a key role in the excellent self-healing and reusable performance. The thermostability of polyurea adhesives was also improved by introducing lignin. This work provides a novel approach for the high-value utilization of low-cost lignin in recyclable adhesives with excellent comprehensive performance.