Diazene-Functionalized Lamellar Materials as Nanobuilding Blocks: Application as Light-Sensitive Fillers to Initiate Radical Photopolymerizations

Abstract

International audienceNew polysilsesquioxane-based lamellar materials, functionalized with radical precursors, were synthesized. They play a double role in the prepa-ration of composite materials: first, as filler homogenously dispersed in the monomer after delamination, second as radical initiator in photopol-ymerization. These polysilsesquioxanes enable fast and efficient photopolymerization upon UV light for thick samples. High conversions in monomers as well as the formation of hybrid polymers covalently linked to the filler are observed. This strategy, based on a double bottom-up approach, avoids the solubility/dispersion problem encountered in the classical preparation of composite polymers from pre-formed organic polymers

Redox two-component initiated free radical and cationic polymerizations: Concepts, reactions and applications

“…Next, still in redox surface functionalization, the work by Ma et al [126] on the functionalization of graphene oxide sheets shows an interesting feature (Scheme 31): low grafting ratio leads to a conservation of the intercalated structure when too fast and high grafting leads to an exfoliated one. This exfoliation was also observed when an extremely fast photopolymerization of lamellar structures was performed [299]. Similarly, other users took advantage of Ce(IV) redox chemistry for the modification of carbon allotropic surfaces [300,301].…”

Probing the efficiency of thermal and photochemical bond homolysis in functionalized nanostructured SBA-15 silicas

“…For this purpose, sophisticated tailor-made materials have been designed, they can roughly be split into two groups. In the first one, the radical precursors are inserted in highly ordered self-assembled systems such as MOF [3], COF [4], PMOS [5] or layered materials [6,7]. In the other group, the paramagnetic species associate through non-bonding interactions to afford a wide array of systems capable to provide confinement.…”

“…Upon irradiation or heating, the decomposition of diazenebased precursors led cleanly to the generation of the targeted radicals. These nanostructured systems enabled to considerably increase the lifetime of transient radicals such as phenoxyl [5,6], arylsulfanyl [6,19,20,21] or arylsulfinyl [22] radicals from hundreds of microseconds to hours, days and even years. The main difficulty encountered with these materials lied in the yields of generated radicals.…”

Polydopamine nano-hybrids : interfacial and photoactive role in epoxy nanocomposites and polymerization

“…Lamellar polysilesquioxanes (POSS) sheets designed with functional groups to generate oxygen or sulphur centered radicals were synthesized from POSS precursors through sol-gel methods. The lamellar nanosheets (scheme 2.7) were then used for FRP of acrylates 126 which were well delaminated in the matrix upon polymerization.…”

“…POSS nanosheet free radical photoinitiators. Image from source 126 . © 2017 American Chemical Society.…”