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

A. GALLASTEGUI; R. SPADA; G. CAGNETTA; R. A. PONZIO; S. MARTINEZ; C. M. PREVITALI; M. L. GOMEZ (*); R. E. PALACIOS; C. A. CHESTA

MACROMOLECULAR RAPID COMMUNICATIONS

WILEY-V C H VERLAG GMBH

Lugar: Weinheim; Año: 2020 vol. 41 p. 1900601 - 1900605

1022-1336

We report herein the use of conjugated polymer nanoparticles (CP NPs) of poly(9,9-dioctylfluorene-alt-benzothiadiazole) (F8BT) and poly(9,9-di-n-octylfluorenyl-2,7-diyl) (PFO) as efficient photoinitiator systems (PIS) of vinyl polymerization in water. CP NPs are biocompatible, excitable with blue commercial LEDs and, unlike visible light Type II PIS, do not need co-initiators to trigger 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 macrophotoinitiator significantly reducing contamination risks due to leaching of low molecular weight byproducts. These combined features make CP NPs PIS notably suitable to synthesize polymeric materials for many healthcare and biomedical applications including drug delivery, tissue engineering, prosthetic implants, food/medicine packaging, etc. These CP NPs PIS were also used to synthesize nano-hydrogels with relatively narrow and controlled size distribution in the absence of surfactants. We propose 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.