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SUMMARY:From Stimuli-Responsive to Renewable Materials
DTSTART:20201002T090000
DTEND:20201002T100000
DTSTAMP:20260408T071059Z
UID:aa48841c9cd5e82584b084acfb93fadda0fdbc71ae1eea3cc27ce2ba
CATEGORIES:Conferences - Seminars
DESCRIPTION:Dr. Céline Calvino\, University of Chicago\, USA\nResponsive 
 materials\, which change their properties in response to an external stimu
 lus (e.g. temperature\, light\, chemical changes) in a predictable manner\
 , allow accomplishing complex tasks such as actuation\, switchable wettabi
 lity\, and sensing. The incorporation of dynamic bonds\, which can rely on
  either non-covalent or covalent interactions\, into polymers have been wi
 dely exploited to impart these new material functionalities. Due to their 
 tunable interaction strength and reversibility\, dynamic interactions can 
 enhance the mechanical properties and processability of functional materia
 ls\, thus making them an attractive alternative to classical covalent link
 ages. In this presentation\, several approaches that exploit supramolecula
 r interactions to prepare polymer materials exhibiting a macroscopic optic
 al response upon mechanical activation are introduced. These so-called mec
 hanochromic systems play an important role for the detection of excessive 
 stress experienced by a material and can thus prevent catastrophic failure
 . As another example\, dynamic covalent chemistry was employed to function
 alize the surface of cellulose nanocrystals (CNCs) under melt processing c
 onditions as a sustainable route for the preparation of homogeneous and me
 chanically enhanced bio-based polymer composites. While CNCs have shown ou
 tstanding reinforcement capabilities when used as a filler in a range of p
 olymer matrices\, their dispersion remains one of the biggest obstacles fo
 r the technological exploitation of such composites. It is shown that the 
 thermal dissociation of dynamic covalent motifs under melt processing cond
 itions and reaction of the resulting products with the hydroxyl groups pre
 sent on the surface of CNCs can be used to functionalize such nanoparticle
 s in situ with molecules of choice. This process was used to modify the su
 rface of the CNCs with small molecules and polymeric species\, leading to 
 a significant mechanical reinforcement of composites materials thus produc
 ed. This concept potentially opens the door to an industrially scalable su
 stainable approach towards the development of nanocellulose bio-composites
 .\n\nBio: Céline was born and grew up in La Chaux-De-Fonds\, Switzerland.
  She received her MS degree from the department of Chemistry at the Univer
 sity of Fribourg\, Switzerland\, with a focus in organic synthesis\, polym
 er chemistry\, and materials science. She completed her master’s thesis 
 at Asulab\, a division of The Swatch Group R&D Ltd\, investigating the for
 mation of homogeneous and resistant anchor layers on the surface of watch 
 components\, and on the introduction of the epilam (anti-spreading agent) 
 effect using controlled polymerization processes via “grafting from” a
 nd “grafting to” methods. Céline stayed in Fribourg to pursue her PhD
  in polymer chemistry and materials at Adolphe Merkle Institute under the 
 supervision of Prof. Christoph Weder. Her thesis focused on the design of 
 chromogenic systems relying on supramolecular interactions and on their in
 corporation into polymeric materials to create new functional mechanorespo
 nsive materials. Céline joined the group of Stuart Rowan at Pritzker Scho
 ol of Molecular Engineering\, at the University of Chicago\, as a postdoct
 oral fellow with a SNFS Mobility Fellowship seeking to enhance her knowled
 ge on the preparation and the use of cellulose nanocrystals\, dynamic cova
 lent bonds and materials engineering. Her ongoing research focuses on the 
 use of dynamic covalent chemistry to functionalize cellulose nanocrystals 
 and on the development of appropriate engineering melt processes for the p
 reparation of mechanically reinforced and sustainable nanocomposite materi
 als.\n\n 
LOCATION:Zoom https://epfl.zoom.us/j/95636623873
STATUS:CONFIRMED
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