Development of Hybrid Polymeric Materials Based on Thiol‐Ene/Cationic Formulations

Abstract

Novel materials were prepared from dual photo and thermal polymerization of hybrid thiol‐ene/cationic systems. In the first stage, the thiol‐ene system proceeded to high conversions, while the cationic photopolymerization was inhibited. The formation of sulfides during this stage was the main factor for the inhibition of the cationic photopolymerization of the epoxy monomers. Once those sulfides were formed, they reacted with the oxonium‐terminated growing polyether chains to form trialkylsulfonium salts. These salts promoted the thermal polymerization of the epoxy monomers in the second stage. The viscoelastic properties of the resulting polymers were measured by DMA.magnified image

Thiol–Ene Click Chemistry

“…These networks exhibited excellent hardness and impact values, which is consistent with the presence of the carbamate groups. In a third approach, by using a dual‐cure process involving a sequential thermal amine‐catalyzed thiol–epoxy reaction followed by a photoinitiated thiol–ene reaction, it was possible to establish a procedure that resulted in high conversions and correspondingly high‐ T g networks 163a–d. The potential of this dual‐thiol‐based chemistry provides another clear method for making multicomponent networks with properties that are not achievable with simple thiol–ene systems.…”

“…The potential of this dual‐thiol‐based chemistry provides another clear method for making multicomponent networks with properties that are not achievable with simple thiol–ene systems. The use of hybrid thiol–ene/epoxy systems in which dual photoinitiated thiol–ene radical and epoxy cationic systems has been greatly expanded in a set of comprehensive reports from Soucek and co‐workers that clearly demonstrate the potential for expansion into a wide range of applications 163b–d. Other hybrid systems involving photopolymerization of divinylsiloxane‐terminated polysiloxanes and a trithiol followed by thermal curing of a cellulose acetate butyrate system to form an interpenetrating polymer network with two distinct glass transitions have also been reported.…”

Thiol‐En‐Klickchemie

“…Die Materialien zeigten exzellente Härtegrade und Schlagfestigkeiten, wie es mit der Anwesenheit von Carbamatgruppen im Einklang ist. Beim dritten Ansatz schließlich wurde ein doppelter Härtungsprozess bestehend aus einer thermischen Amin‐katalysierten Thiol‐Epoxy‐Reaktion und einer nachfolgenden photoinitiierten Thiol‐En‐Reaktion angewendet 163a–d. Dieses sequenzielle Herstellungsverfahren ermöglicht die Bildung von Mehrkomponentennetzwerken mit Eigenschaften, die mit einfachen Thiol‐En‐Systemen nicht erreichbar sind.…”

“…Dieses sequenzielle Herstellungsverfahren ermöglicht die Bildung von Mehrkomponentennetzwerken mit Eigenschaften, die mit einfachen Thiol‐En‐Systemen nicht erreichbar sind. Die Verwendung von Thiol‐En/Epoxy‐Hybridsystemen bestehend aus einer photoinitiierten Thiol‐En‐Radikalkomponente und einer kationischen Epoxykomponente ist durch Soucek und Mitarbeiter ausgiebig erforscht worden 163b–d. Andere Hybridsynthesen bestehend aus der Photopolymerisation von Divinylsiloxan‐terminierten Polysiloxanen mit einem Trithiol und der anschließenden thermischen Härtung eines Celluloseacetatbutyratsystems zur Bildung von verzahnten Polymernetzwerken (IPNs; interpenetrating polymer networks) mit zwei separaten Glasübergängen wurden ebenfalls beschrieben.…”

Preparation and Study of Shape Memory in Epoxy Resins

“…Likewise it was prepared a thiol‐ene/thiol‐epoxy hybrid system, using a free‐radical photoinitiator and a photo‐base generator . Similar systems, were investigated by our group of work at the Center for Research in Applied Chemistry (CIQA) inducing cationic thiol‐epoxy reactions using a photoinitiator together with amine as catalyst that undergoes photolysis to protonate the epoxy resin.…”