Conjugated Polymer Nanoparticles as Unique Coinitiator‐Free, Water‐Soluble, Visible‐Light Photoinitiators of Vinyl Polymerization

Abstract

The use of conjugated polymer nanoparticles (CP NPs) of poly(9,9‐dioctylfluorene‐alt‐benzothiadiazole) and poly(9,9‐di‐n‐octylfluorenyl‐2,7‐diyl) as efficient photoinitiator systems (PIS) of vinyl polymerization in water is reported herein. CP NPs are biocompatible, excitable with blue commercial LEDs and, unlike visible light Type II PIS, do not need co‐initiators to trigger a monomer chain reaction. CP NPs photoinitiate polymerization of a variety of acrylic monomers with initiation rates comparable to those observed for well‐known Type II PIS. Given the extraordinarily large molar absorption coefficients of CP NPs (≈108 m‐1 cm‐1) very low particle concentration is required for effective polymerization. Additionally, CP NPs behave as conventional macrophotoinitiators significantly reducing contamination risks due to leaching of low molecular weight byproducts. These combined features make CP NPs PIS suitable to synthesize polymeric materials for many healthcare and biomedical applications including drug delivery, tissue engineering, prosthetic implants, and food/medicine packaging. These CP NPs PIS are also used to synthesize nano‐hydrogels with a relatively narrow and controlled size distribution in the absence of surfactants. It is proposed that polymerization is initiated at the CP NPs surface by photogenerated free polarons, in close analogy to the mechanism previously described for PIS based on inorganic semiconductor NPs.

Exciton Diffusion, Antenna Effect, and Quenching Defects in Superficially Dye-Doped Conjugated Polymer Nanoparticles

“…Additionally, doping of CPNs with reducing or antioxidant species has been shown to increase their fluorescence quantum yield, suggesting that these species decrease the polaron concentration . Finally, we recently reported the use of F8BT CPNs as photoinitiators of vinyl polymerization reactions and proposed a mechanism based on the presence of surface-accessible polarons . It is conceivable that water at the particle surface could help stabilize or trap these polarons.…”

“…Multichromophoric systems displaying good AE are those that show excellent photon collection capability (i.e., large absorption cross section) combined with efficient ET of the collected excitation energy to a few acceptors. Systems displaying high AE produce a higher concentration of the acceptor’s excited state than would be observed upon direct excitation; thus, they have practical advantages when used as active materials in luminescent probes, , photocatalysts, polymerization photoinitiators, solar cells, optical sensors, phototherapies, and so forth.…”

Advances in microfabrication technologies in tissue engineering and regenerative medicine

“…For instance, the light source should efficiently crosslink the precursor solution while keeping cell viability and protein structure intact 19,40 . In the meantime, UV‐activated initiators, such as poly(9,9‐dioctylfluorene‐alt‐benzothiadiazole) and poly(9,9‐di‐n‐octylfluorenyl‐2,7‐diyl), were some of the most widely used light‐sensitive compounds for the polymerization of vinyl‐based molecules 41,42 . Nonetheless, as these UV‐activated initiators can generate dangerous side effects on cells, other alternatives have been proposed, such as camphorquinone, 1‐phenyl‐1,2‐propanedione, Irgacure®819, and VA‐086 43,44 .…”

“…19,40 In the meantime, UV-activated initiators, such as poly(9,9dioctylfluorene-alt-benzothiadiazole) and poly(9,9-di-noctylfluorenyl-2,7-diyl), were some of the most widely used light-sensitive compounds for the polymerization of vinyl-based molecules. 41,42 Nonetheless, as these UVactivated initiators can generate dangerous side effects on cells, other alternatives have been proposed, such as camphorquinone, 1-phenyl-1,2-propanedione, Irgacure®819, and VA-086. 43,44 Furthermore, photomask's micropatterns should possess an appropriate resolution to be successfully transferred into the fabricated material.…”

Fast Visible-Light Photopolymerization in the Presence of Multiwalled Carbon Nanotubes: Toward 3D Printing Conducting Nanocomposites

“…To avoid these drawbacks, novel PISs have been developed, such as macromolecular photoinitiators, photoactive polymers, and functionalized monomers, in order to obtain fast photopolymerizaiton processes. These PIS systems are being used to obtain multifunctional materials, new inks, and formulations for light-induced additive manufacturing 3D printing methods. ,,− …”