Polyaromatic Structures as Organo-Photoinitiator Catalysts for Efficient Visible Light Induced Dual Radical/Cationic Photopolymerization and Interpenetrated Polymer Networks Synthesis

Abstract

International audienceDifferent polyaromatic structures (truxene derivatives and tris(aza)pentacene) are presented as new metal-free organic photocatalysts (OPC) to promote free radical polymerization FRP and ring-opening polymerization (ROP) under halogen lamp, household LED bulb, and laser diode (405 nm). These OPCs exhibit interesting light absorption properties and lead, through an oxidative catalytic cycle, to the formation of radicals and ions that can initiate both free radical polymerization FRP and ring-opening polymerization ROP. Interestingly, excellent polymerization profiles are obtained even upon visible light exposure. Using these very soft irradiation conditions, acrylate/epoxide blends are also easily polymerized under air and lead to the formation of interpenetrated polymer networks IPN exhibiting no phase separation

Photochemical Production of Interpenetrating Polymer Networks; Simultaneous Initiation of Radical and Cationic Polymerization Reactions

“…The final coatings are tack-free. Such useful PIs in these novel dual photoinitiating systems are derived from dye structures and include e.g., diketopyrrolopyrrole-thiophene derivatives [107], mono and polyfunctional thiophene derivatives [108], indanedione skeleton [109], naphthalene scaffold [110], naphthalimide and naphthalic anhydride derivatives [111], anthraquinone derivatives [112], chalcone derivatives [113], push-pull malonate and malonitrile based compounds [114], naphthalimide based methacrylated derivatives [115], α-silicon polyoxomolybdate [116], acridinediones [117], difunctional acridinediones [118], Keggin-type polyoxometalate ion [119], push-pull structured indandiones [120], dimethyldihydropyrene [121], chromone based compounds [122], perylene bis-dicarboximides [123], pyrene derivatives [124], zinc complexes [125], pyridinium salts [126], pyrromethenes [127], trifunctional triazines [128], cyclometallated Pt(II) complexes [129], polyaromatic structures [130], and phenanthroline ligand containing Ru complex [131].…”

“…The high reactivity of the photoinitiating systems is exemplified by the fact that low viscosity formulations where oxygen inhibition is much more important can be used (e.g., acrylate (TMPTA)/epoxide (EPOX), acrylate (TMPTA)/divinylether (DVE), thiol (trimethylolpropane tris (3-mercaptopropionate) TMSH)/divinylether (DVE)). For example, the manufacture of IPN materials can be carried out under exposure to a large variety of wavelengths delivered by a Hg-Xe lamp (intensity ~40 mW/cm −2 ) [116,119,128,130] or laser diodes (intensity ~80 mW/cm −2 ) at 385-405 nm [110], 457 nm [108,111,[113][114][115]122,124], 473 nm [127], 473 nm (and likely 532, 635 nm) [120], 532 nm [107,123], 635 nm [112], from 473 up to 635 nm [121]. This was achieved under air (for EPOX/TMPTA blends) or in laminate (for EPOX/DVE blends as seen, e.g., in [124,125,127,128]).…”

“…For example (see in [130]; Hg-Xe lamp exposure), the contact angle on the surface of the EPOX/TMPTA (50%/50%) IPN film (water/polymer) is 62° which can be compared to those of neat TMPTA (49°) and neat EPOX (67°): both the polyether and polyacrylate networks are thus present at the surface. DMA analysis leads to one Tg value (148 °C) suggesting that a phase separation is avoided (or at least limited) and supporting a good compatibility between the two chemical networks.…”

“…Three representative examples are the following. When the polyaromatic chromophore depicted in Figure 2a is used in combination with DPI and a silane (or NVK) under a halogen lamp, an efficient simultaneous TMPTA/EPOX polymerization with final conversions of 55% (EPOX) and 75% (TMPTA) is readily achieved [130].…”

Photopolymerization Reactions: On the Way to a Green and Sustainable Chemistry

“…The current efforts result in an amazing series of proposals of new PISs . For example, we have recently introduced PISs ( [99][100][101][102][103][104][105][106][107]) exhibiting really novel absorption properties (red-shift absorptions, multicolor absorptions, enhanced molar extinction coefficients, ε): e.g., colored substituted or functionalized ketones [60], modified organometallic derivatives [70][71][72][108][109][110][111][112][113][114][115][116][117] (ruthenium-, iridium-, platinum-, zirconium-and zinc-based complexes, titanocene derivatives…), various series of dye-based skeletons [61][62][63][65][66][67][68][74][75][76] (e.g., phenylenediamine, polystilbene, polyazine, violanthrone, acridinedione, 2,7-di-tert-butyldimethyldihydropyrene, bodipy, boranyl, thiophene, perylene bis-dicarboximide, hydrocarbons, pyrromethene, pyridinium salt…), di-and tri-functional architectures of photo initiators [64], light harvesting compounds [57,58] (where a strong molecular orbital coupling occurs, leading to ε huge values) and push-pull and multicolor photoinitiators (novel chromophores; donor--acceptor arrangements; unusual broad absorptions from the blue to the red wavelengths…).…”