Rückmeldungs-Mechanismen für Mechanoresponsive Funktionale Materialien
Polymermaterialien
Zusammenfassung der Projektergebnisse
During the course of the project “feedback mechanisms for mechanoresponsive functional materials” a number of significant advances in the field of polymer mechanochemistry were realized. Firstly, I showed that it is possible to produce a polymer that can reinforce itself when subjected to mechanical stress while simultaneously sending out an optical signal where the stress is concentrated. Not only contributes this functional duality considerably to the advancement of smart materials but I moreover unprecedentedly utilized stabilized radicals to initiate this self-reinforcement process by free radical polymerization paving the way for a whole new class of mechanochemically self-reinforcing materials. Moreover, I could develop the most sensitive steady-state optical probe for mechanical stress reported so far allowing the detection of force in bulk materials at low optical probe percentages. This fluorescent motif improves a number of disadvantages over reported optical probes, i.a. considerably enhanced fluorescence efficiency and shifting of the excitation and emission spectra towards the visible region. While I expect this molecule to have a considerable impact on the community, I also employed it to investigate fundamental material properties of hydrogels moving the field of mechanochemistry to the aqueous phase. Interestingly here I could show that the stress activation of the probe is highly dependent on the morphology of the employed hydrogels, i.e. glassy, rubbery, or mixed state. Unexpectedly, classical mechanical analysis and utilization of the optical probe gave contradictory results over the identity of the glass transition prospectively allowing insights into differences of macroscopic and nanoscopic stress dissipation. Eventually, optical stress-sensing in the aqueous phase was brought to a new level when I showed that the noncovalent self-assembly of amphiphilic block copolymers into larger superstructures in water creates sufficient drag to mechanochemically cleave an optical probe previously not activatable in homogeneous solution. This work lays the foundation for covalent mechanochemistry induced in biologically relevant molecular assemblies and thus optical stress-sensing in living systems. I believe that over the course of this project I could successfully innovate with new chemistry while simultaneously tackling unsolved fundamental questions regarding material properties and bringing stress-sensing to the unexplored aqueous phase. I am thus confident that the resulting publications will receive attention in- and outside of the community.
Projektbezogene Publikationen (Auswahl)
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ACS Macro Lett. 2016, 5, 995–998
H. Li, R. Göstl, M. Delgove, J. Sweeck, Q. Zhang, R. P. Sijbesma, J. P. A. Heuts
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Chem. Commun. 2016, 52, 8608–8611
F. Verstraeten, R. Göstl, R. P. Sijbesma
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Chem. Sci. 2016, 7, 370–375
R. Göstl, R. P. Sijbesma
