Controlled reversible aggregation of thermoresponsive polymeric nanoparticles by interfacial Diels-Alder reaction

Hypothesis: Stimuli-responsive polymers, with properties changing upon different environmental factor variations such as pH, light, mechanical stress or temperature, and polymeric nanoparticles have found many important applications in fields such as drug delivery, biosensing and environmental research.Experiments: In this work, thermoresponsive nanoparticles that are able to react by Diels-Alder reaction (a dienedienophile cycloaddition) were studied. Thermoresponsive polymers were synthesized from a biocompatible polymer (poly(lactic-co-glycolic) acid, PLGA) and diene (furan) or dienophile (maleimide) derivatives. Emulsification-evaporation method was then used as a fast and reproducible method to obtain highly monodispersed polymeric nanosuspensions able to react by Diels-Alder (DA) reaction.Findings: The nanoparticles' size decreased down to 25 nm by increasing the emulsification's time. The possible direct and retro-Diels-Alder (rDA) reactions between furan- and maleimide-functionalized nanoparticles were studied by dynamic light scattering and electron microscopy. For the first time, the reactivity of the interfacial DA and rDA reactions between functionalized-nanoparticles was studied, leading to the determination of the activation energy, the enthalpy of activation and the entropy of activation.

Automated summary

This study focuses on thermoresponsive nanoparticles that can react through Diels-Alder reaction in response to environmental changes. The size of the nanoparticles decreases with increasing emulsification time. Additionally, the reactivity of interfacial DA and rDA reactions between functionalized nanoparticles is investigated for the first time.