Polyarylene Networks via Bergman Cyclopolymerization of Bis‐ortho‐diynyl Arenes

Abstract

Bis‐ortho‐diynylarene (BODA) monomers, prepared from common bisphenols in three high yielding steps, undergo free‐radical‐mediated thermal polymerization via an initial Bergman cyclo‐rearrangement. Polymerization is carried out at 210 °C in solution or neat with large pre‐vitrification melt windows (4–5 h) to form branched oligomers containing reactive pendant and terminal aryldiynes. Melt‐ and solution‐processable oligomers with weight‐average molecular weight Mw = 3000–24 000 g mol–1 can be coated as a thin film or molded using soft lithography techniques. Subsequent curing to 450 °C affords network polymers with no detectable glass transition temperatures below 400 °C and thermal stability ranging from 0.5–1.5 % h–1 isothermal weight loss measured at 450 °C under nitrogen. Heating to 900–1000 °C gives semiconductive glassy carbon in high yield. BODA monomer synthesis, network characterization and kinetics, processability, thin‐film photoluminescence, and thermal properties are described.

Recent advances of the Bergman cyclization in polymer science

“…In the case of homo-polymerization, a variety of rigid conjugated polymers with excellent thermochemical properties are obtained through the Bergman cyclization [23,25,29]. Attempting to resolve the fundamental principles in this field, we published the first report on the on-surface formation of one-dimensional polyphenylene chains through a Bergman cyclization on a Cu(110) surface [30].…”

“…Tour et al [23] firstly ran a radical polymerization via a thermally-triggered Bergman cyclization and obtained conjugated aromatic polymers such as poly(p-phenylene)s (PPPs) and polynaphthalenes (PNs) in 1994, thereby highlighting the Bergman cyclization as a new synthetic tool for polymers or other materials. Smith and co-workers [24,25] subsequently used the Bergman cyclization of bis(o-diynylarene) to form branched oligomers at 210 °C, which could either react with carbon nano-onions to improve their solubility, or be carbonized to generate glassy carbon. Moore et al [26,27] used diradicals generated via a Bergman cyclization to initiate the radical polymerization of a variety of vinyl monomers.…”

A comparison of outcomes from treating hepatocellular carcinoma by hepatic artery embolization in patients younger or older than 70 years

“…Moore et al74, 75 used the diradicals generated from Bergman cyclization of macrocyclic enediynes to investigate their behaviors in initiating free radical polymerizations of various functionalized olefines. Smith et al76, 77 reported preparation of a prenetwork polyarylene via Bergman cyclization polymerization of bis‐ ortho ‐diynylarene (BODA) monomers. The cured BODA network polymers can serve as excellent precursors for glassy carbonous materials.…”

Coordination‐Accelerated Radical Formation from Acyclic Enediynes for Tumor Cell Suppression

“…The thermal reactivities of the ligand EDY and metalloenediyne complexes ( EDY‐M ) were evaluated by differential scanning calorimetry (DSC) analysis. As shown in Figure , the EDY exhibits a sharp endothermal melting peak at 159 °C, followed by an exothermal peak corresponding to the cycloaromatization and the polymerization of free radical intermediates . The onset temperature of ligand EDY is 163 °C, suggesting that the ligand EDY is thermally inert at room temperature.…”