Self-sensitized photopolymerization of pyrrole

Abstract

Polypyrrole has been photochemically deposited on different kinds of solid surfaces by illumination with sunlight; this has been interpreted as the consequence of a self-sensitited initiation process.The search for new conducting materials of a polymeric nature has led to numerous reports, especially dealing with electrochemical growth of such substances.1--3 Recently, two new methods for photo-sensitized polymerization of pyrrole using Ru(bpy)32+ and CuI(dp)*+ (5) (where bpy = bipyridine and dpp = 2,9-diphenyl-1 ,lo-phenanthroline) as sensitizers, have been published.Herein we report a direct photochemical process in which the pyrrole molecules act as photosensitizers. This simple procedure involves exposing an aqueous solution of pyrrole deposited onto a solid surface to sunlight. We chose glass, mica, and glass doped with Sn02 as the substrates for polymerization.Two types of experiments were performed. The first involved maintaining a HC104 (1 M) and pyrrole (0.5 M) suspension in water under atmospheric pressure while irradiating for around 15 h on a glass plate of approximately 3 cm2 area. A black polypyrrole film with a metallic lustre of around 100 nm thickness (measured with a Taylor Hobson Talistep) and with a conductivity of around 10-3 Q-1 cm-1 was formed.

Role of External Field in Polymerization: Mechanism and Kinetics

“…The photopolymerization method is considered as a good alternative to electropolymerization for the preparation of conjugated polymers. For instance, polypyrrole has been photochemically synthesized with and without the metal photocatalyst. − Since the early 1990s, Iyoda and Shimidzu carried out some preliminary works on the photochemical solution polymerization of thiophene derivatives, i.e., benzo­[ c ]­thiophene, oligothiophenes, and dithienothiophenes, in the presence of an electron acceptor, e.g., dinitrobenzene, CCl 4 . − The authors envisioned that the step-growth propagation was driven by the successive coupling reactions of cation radical species, which were generated by the photoinduced electron transfer from the excited monomer to the electron acceptor. Furthermore, a series of water-soluble thiophene derivatives were polymerized with the addition of photocatalyst potassium dichromate .…”

Fabrication of 3D conjugated polymer structures via vat polymerization additive manufacturing

“…A photoinitiating system isn't strictly needed to photopolymerize pyrrole. Studies by Rodríguez and González-Velasco (1990) have shown that pyrrole itself can be excited by UV irradiation to initiate photopolymerization. This self-sensitized polymerization technique however requires long irradiation times and produces a polymer with a low conductivity (Rodríguez and González-Velasco, 1990).…”

A structural and morphological comparative study between chemically synthesized and photopolymerized poly(pyrrole)

“…25,26 Previously, there were reports on the multiphotonsensitized polymerization of pyrrole, self-sensitized photopolymerization of pyrrole and photopolymerization of pyrrole using ruthenium complexes, cobalt complexes, and copper complexes as electron acceptors. 27,28 However, few reports on photopolymerization were found during a comprehensive literature survey.…”