The interplay between macromolecules and supramolecular polymers

Supramolecular polymers have robust mechanical properties and can dynamically exchange their building blocks, which has prompted researchers to work on the development of supramolecular polymeric materials, or hybrid materials, possessing both characteristics.

However, this combination brings added complexity and demands a deeper fundamental understanding of the interaction between the two employed chemistries.

Hybrid materials

Hybrid materials are composed of both supramolecular polymers or motifs and macromolecules. The irreversible nature of the covalently bonded building blocks in macromolecules gives rise to excellent mechanical properties, as known from conventional plastic materials.

However, this makes recycling a challenging task. Supramolecular polymers, on the other hand, consist of building blocks held together by relatively weak interactions, such as hydrogen bonds and ionic interactions, enabling reusability. By combining these two components, materials with intriguing, dynamic, and 'smart' properties can be developed.

Although research in recent decades has led to the creation of numerous new hybrid materials, control over their morphology (shape and structure), and consequently the ultimate material properties, remains complex.

This is partly due to the many diverse potential interactions with solvents, possible other components, and themselves. The aim of the PhD research of Joost van der Tol was to gain a better understanding of the interplay between supramolecular motifs or polymers and macromolecules.

Reinforcement

Along with his collaborators, van der Tol began by incorporating supramolecular building blocks, which acted as reinforcement components, into a macromolecular network.

These reinforcements were added in various fractions, either as 'filler' or were covalently linked to the macromolecular network, which resulted in distinct morphologies and controllable material properties.

Besides enhancing and controlling the properties of hybrid polymeric materials, van der Tol also explored their processability. In particular, macromolecules grafted with supramolecular motifs, which often form strong networks through intermolecular interactions, sparked his interest.

By using controlled conditions, van der Tol could intramolecularly trap the supramolecular side chains, resulting in lower viscosity and improved processability. This strategy was further extended by introducing light-sensitive groups onto the supramolecular motifs, allowing van der Tol to switch the network formation on and off with high precision using ultraviolet light.

Combination

In a next step, van der Tol explored how supramolecular polymers and macromolecules could be combined in an innovative and less synthetically invasive manner to develop functional supramolecular polymeric materials.

First, he examined the influence of solvents (or processing fluids) on the morphology of supramolecular polymers using solubility parameters. This extensive study later served as the basis for more complex systems involving the addition of macromolecules to the solution.

This research provided crucial insights into the impact of macromolecules on supramolecular polymers, which are vital for subsequent steps towards applicable and functional hybrid materials.

Fundamental foundation

In summary, the thesis of Joost van der Tol sheds light on the interplay between supramolecular polymers and covalently bonded macromolecules.

This enhances the current understanding of how the morphology of hybrid materials affects a material's ultimate properties and how it can be controlled.

Furthermore, van der Tol and his colleagues laid a fundamental foundation for the development of functional hybrid materials by studying supramolecular polymers and macromolecules in a fundamentally grounded and innovative manner.

Title of PhD thesis: Supramolecular Polymeric Materials - The interplay between macromolecules and supramolecular polymers. Supervisors: Bert Meijer and Ghislaine Vantomme.