Predicting properties of aminated associated polymers as they age
Predicting properties of aminated associated polymers as they age lead image
Some classes of associating polymers have shown promise for use as reversible self-healing adhesives. These aminated polymers have been shown to age and harden over time, especially under higher temperatures. Certain situations may call for a firmer storage modulus, which diminishes the materials’ self-healing ability.
Using rheology, differential scanning calorimetry, infrared microscopy, and small-angle X-ray scattering, Zhang et al. developed a model of aging behavior in this class of associating polymers.
“We have demonstrated the power of amine hydrogen bonding,” said author Savvas Hatzikiriakos. “While amines are a generally weak hydrogen bond, when present in large numbers in the backbone of polyolefins, they co-operate to create self-healing adhesives and coatings. Even the use of small molecules with amination can create networks that mimic properties of large molecules or properties of crosslinked elastomers.”
Shear rheology demonstrates the degree to which a sample’s modulus changes with time and temperature, which provides a means to model the degree of aging. Calorimetry and infrared microscopy have also shown this time-temperature-related aging behavior.
“Due to the weak nature of the type of molecular associations in our system, we initially thought these systems were stable,” Hatzikiriakos said. “However, we were surprised to see their time-dependent properties continuously change with time and temperature, and the aggregation of the weak associations could lead to a strong network that is not usually observed in other associating polymer systems.”
The researchers hope their work stokes further interest in associating polymers and that their model helps predict both how much a sample has aged and forecast expected properties under certain aging parameters.
Source: “Rheology and aging of amine functionalized polyolefins,” by Z. Zhang, B. M. Yavitt, Elmira Mohammadi, L. L. Schafer, and S. G. Hatzikiriakos, Journal of Rheology (2024). The article can be accessed at https://doi.org/10.1122/8.0000895 .
