- A new study shows how multiscale simulations can reveal when nanoscale interphases enhance the properties of nanocomposites.
- This breakthrough will enable researchers to identify promising material combinations before experimental synthesis and testing.
A Spanish research team has demonstrated a computational approach for predicting how interactions at the boundary between different materials can influence the performance of nanocomposites.
The research, conducted by the IMDEA Materials Institute and BCMaterials, was recently featured on the cover of the Advanced Materials in Spain special issue of Advanced Materials, one of the world’s leading materials science journals. The special issue brings together contributions from advanced materials research groups across Spain and arose from the Spanish Advanced Materials Programme.
Nanocomposites combine two or more materials to achieve properties that cannot be obtained easily from a single constituent. Their behaviour, however, cannot always be predicted simply from the properties and proportions of the individual components.
One reason for this is the formation of an interphase: a nanoscale region created where two different materials come into contact.
“When two materials are combined at the nanoscale, the region between them is not simply a sharp boundary,” explains Dr. Maciej Haranczyk, Principal Investigator at IMDEA Materials Institute and one of the authors of the study. “An interphase forms with properties that may differ from either constituent. Under the right conditions, this region can make a substantial contribution to the behaviour of the entire composite.”
These interphase effects can give rise to synergistic behavioUr, in which the measured property of a composite exceeds the value expected from conventional mixture models.
Such effects have been observed experimentally in nanocomposites for properties including thermal and ionic transport (the movement of heat and charged ions through a material). However, identifying promising combinations has generally required materials to first be synthesised and characterised.
The new work demonstrates how simulations can instead be used to evaluate the contribution of the interphase before fabrication.
Using atomistic simulations, the researchers calculated properties associated with the nanoscale region between the constituent materials. These results were then incorporated into larger-scale continuum models to predict the behaviour of the complete composite.
“The important step is that we can explicitly represent the interphase and examine how it changes the predicted macroscopic property,” says Dr. Haranczyk. “This creates the possibility of screening material combinations computationally and identifying those in which interphase effects may produce particularly interesting behaviour before committing to experimental synthesis.”
From experimental screening to simulation-guided design
The researchers demonstrated the approach using metal-organic frameworks (MOFs) incorporated into polymers. MOFs are highly porous crystalline materials with potential applications in areas ranging from molecular separation to energy technologies. For practical use, they are often incorporated into polymers, creating mixed-matrix or other MOF-polymer composite materials.
Predicting the properties of these composites is challenging as their behaviour depends not only on the MOF and polymer themselves, but also on the nanoscale region, or interphase, formed where the two materials meet.
To address this challenge, the team developed a multiscale simulation framework combining atomistic molecular dynamics with continuum physics-based models.
For thermal transport, the atomistic simulations were used to resolve heat transfer across the nanometer-scale MOF-polymer interphase. The resulting information was then passed to continuum models capable of predicting the thermal conductivity of the larger composite structure.
In total, three MOF–polymer nanocomposite systems were investigated. For one system based on HKUST-1, explicitly accounting for the interphase produced a predicted thermal conductivity approximately 30% higher than the corresponding reference prediction in which the interphase contribution was not included.
Importantly, the same enhancement was not observed for all of the investigated combinations, with another MOF-polymer system tested showing no comparable improvement.
This difference is significant as it demonstrates that enhanced thermal transport is not an automatic consequence of forming a nanocomposite. Instead, it depends on the specific interactions and transport properties of the interphase formed by a particular combination of materials.
“Synergy is not universal,” says Dr. Haranczyk. “That is precisely why predictive tools are useful. The goal is not simply to explain an enhancement after it has been observed, but to understand which combinations are likely to produce favoUrable interphase effects and which are not.”
The research was carried out largely within the framework of the Marie Skłodowska-Curie Actions M4MID project, undertaken at IMDEA Materials Institute and led by Dr. Phuong Vo.
The researchers believe the approach could contribute to a broader transition from experimentally intensive screening toward simulation-guided materials discovery, particularly for systems in which interfaces and interphases strongly influence macroscopic properties.
“Ultimately, this kind of multiscale modelling could help us explore much larger materials spaces and develop nanocomposites in which the interphase itself becomes a deliberate part of the design. In the longer term, this approach could support the development of new composite materials for applications ranging from molecular separation and carbon capture to energy technologies.”
This research was funded in part by the European Union under Grant Agreement 101067497. Views and opinions expressed are, however, those of the author(s) only and do not necessarily reflect those of the European Union. Neither the European Union nor the granting authority can be held responsible for them.