Research & Vision

"Exploit adaptive polymers to render materials renewable"

Reprocessable Thermosets

Thermosets are an important class of plastic material present in a wide range of daily life applications. However, due to their inherent network macromolecular structure, these valued materials cannot be reprocessed nor be recycled and thus strongly contribute to the current global concern of plastic waste pollution. This research proposes an alternative to these non-recyclable thermosets via the preparation of multi-stimuli responsive building blocks that enable a controlled and reversible polymerization. The rational combination of various stimuli-responsive chemical systems is expected to give access to polymer networks that can be dissociated into their orignial building block unit. Such advanced technology does not only improve controlled reshaping and repairing processes but also pave the way to chemical recycling processes of polymer networks.

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Photoresponsive Polymer Additives
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Multifunctional Polymer based on Encapsulated Systems

This research exploit the concept of encapsulated chemistries to impart new functionalities to polymer material, such as self-healing, self-destructing and self-reporting. The use of capsules permits imparting new functionalities without the need of chemical modification, but instead, simple incorporation of the active capsules within the polymer matrix. The approach is strikingly simple and versatile in terms of activation modes and responses that can be achieved.

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Although plastics have defined the modern era, a lack of innovative schemes regarding their end of life has had disastrous environmental and public health consequences. Anticipating predicted increases in plastic consumption, there is a critical need for the development of initiatives that address plastic pollution. 

 

Responsive adaptive polymers, that can change their properties in a predictable manner in response to an external stimulus (e.g. temperature, light, chemical changes, force, magnetic/electric field), are an emerging class of materials that can fill this circular critical need and provide a universal approach to render plastics renewable.

The Calvino group vision focuses on the development of light-mediated adaptive polymers that incorporate advantageous photoswitchable motifs to improve controlled reprocessing, reshaping, and repairing processes. In such systems, the irradiation of light triggers molecular reactions that enable a controlled and permanent breaking/forming of the macromolecular chains, ultimately permitting the polymer reuse.

In this research the group seeks to explore the fundamentals of light-mediated responsive motifs at the molecular level (in solution) to transpose efficiently these motifs into solid state (in bulk). To understand the influence of the molecular mechanistic on the light-mediated phase transition of the materials, these motifs will be investigated in a systematic manner starting with simple organic compounds to more complex systems such as molecular blends, linear polymers, and polymer networks. This program will allow a systematic progression towards the incorporation of photo-responsive functional groups into different polymer architecture through different conceptual approaches that enable reprocessing.

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Dynamic Covalent Gated Chemistry
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This research focuses on the design of photoswitchable motifs that enable a controlled formation and scission of covalent bonds via reversible [2+2]-photocycloaddition. Our aim is to create photochemical motifs that can react reversibly under mild conditions, in the visible and UV-A range and produce high conversions. Different strategies such as the extension of the conjugated π-system, the introduction of electron withdrawing/donating  groups are methodically employed to create photoswitches with improved photochemical performance. The development of such effective motifs plays a key role towards the targeted reversible photopolymerizations. 

Bio-based polymers are not used on large scale mainly because their raw properties are not comparable with their petroleum-based counterparts. One of the strategies to improve the brittleness of these renewable materials is crosslinking. Since conventional crosslinking implies the formation of thermosets, these polymers cannot be reprocessed and they accumulate as litter after few uses. To address this problem, we aim to create small organic molecules that respond to different stimuli, developing crosslinking pathways for these additives to be able to bond and de-bond on demand. This way, polymeric materials can fit the so-called cradle-to-cradle system