Mechanically controlled radical polymerization initiated by ultrasound

Polymer Networks: From Plastics and Gels to Porous Frameworks

“…In a related vein, and somewhat reminiscent of light‐induced polymer network strand growth (see Section 3.3.4) for network strengthening, the random homolytic cleavage of covalent bonds that occurs upon excessively straining polymer networks has been used to induced network healing via the growth of new polymer strands . Moreover, piezoelectric materials such as zinc oxide or even water, which are capable of generating free radicals in response to low‐amplitude, high‐frequency vibrational forces (e.g., ultrasound), have been used to control polymer growth; this strategy could provide another means to design self‐strengthening networks. In the future, novel mechanophore designs coupled with additive manufacturing strategies will enable the development of novel classes of polymer networks ranging from optimized elastomers to advanced metamaterials …”

Polymernetzwerke: Von Kunststoffen und Gelen zu porösen Gerüsten

“…Auf ähnliche Weise – und an das lichtinduzierte Wachstum von Strängen in Polymernetzwerken (siehe Abschnitt 3.3.4) zur Verfestigung von Netzwerken erinnernd – wurde die zufällige homolytische Spaltung von kovalenten Bindungen, die nach übermäßiger Belastung des Polymernetzwerks erfolgt, für die induzierte Selbstheilung des Netzwerks durch das Wachsen neuer Polymerstränge genutzt . Außerdem wurden piezoelektrische Materialien wie Zinkoxid oder selbst Wasser, die freie Radikale als Reaktion auf Schwingungen mit hoher Frequenz und kleiner Amplitude (z. B. Ultraschall) bilden können, zur Steuerung des Polymerwachstums verwendet; diese Strategie könnte eine weitere Möglichkeit zur Entwicklung von selbst‐verfestigenden Netzwerken sein.…”

Synthesis of Riboflavin‐Based Macromolecules through Low ppm ATRP in Aqueous Media

“…It can be triggered by the introduction of a reducing compound, for example, radical initiator in initiators for continuous activator regeneration (ICAR) ATRP, chemical reducing agents (e.g., glucose, ascorbic acid, hydrazine), and metallic silver in activators regenerated by electron transfer (ARGET) ATRP, zerovalent metals (Fe 0 , Cu 0 ) in supplemental activator and reducing agent (SARA) ATRP. Alternatively, an external stimuli such as a reducing current in electrochemically mediated ATRP ( e ATRP) and simplified electrochemically mediated ATRP ( se ATRP), light in photo‐induced ATRP (photo‐ATRP), or mechanical forces in mechanically induced ATRP (mechano‐ATRP) and in ultrasonication‐induced ATRP (sono‐ATRP) can be applied . Electrochemistry offers additional opportunity to catalyst recycle, eliminates needs for chemical reducing agents, provides temporal control during the process, and extends polymerization to aqueous media .…”