P dioxane

Poly(propylene oxide) (PPO) and the utilized solvents were acquired from Sigma Aldrich (now Merck), St. Louis, MO, USA. The chemical structure of the polymer is displayed in Scheme 1.
The polymer solutions were prepared by dissolving 2.5 g of PPO powder in 100 mL of each of the following solvents, acquired from Sigma Aldrich (now Merck): benzonitrile (anhydrous, ≥99%), carbon disulfide (anhydrous, ≥99%), chloroform (anhydrous, ≥99%, contained 0.5–1.0% ethanol as a stabilizer), ethyl acetate (anhydrous, ≥99.8%), and p-dioxane (anhydrous, ≥99.8%). The pH of the polymer solutions did not vary intentionally during experiments, and the small variations were caused by the combination of PPO (pH = 4) with the selected solvents having pH values comprised between 4 and 7.

Copper nitrate hemi-pentahydrate (99%), bromine, and tetraphenylethene (TPE, 98%) were purchased from Alfa Aesar. Cobalt nitrate hexahydrate was purchased from J. T. Baker. Zinc nitrate hexahydrate (99%) was purchased from Beantown Chemical. Nitric acid and tetrahydrofuran were purchased from Fisher Scientific. N,N-dimethylformamide (DMF) was purchased from MilliporeSigma, while N,N-dimethylacetamide (DMAc), potassium hydroxide, p-dioxane, dichloromethane (DCM), ethanol, and methanol were purchased from EMD Millipore. (3-(methoxycarbonyl)phenyl)boronic acid (95%) was purchased from Oxchem. Cesium fluoride and pyrazine were purchased from Oakwood Chemical. Tetrakis(triphenylphosphine)palladium(0) (99%) was purchased from Strem Chemicals. Nanopure water was made using a Barstead Nanopure with a D5026 organic free filter kit. All chemicals were used as received without further purification.

Silicone rubber (SR) (1 mm in thickness) was provided by Goodfellow (HuntingdonUK). We washed the SR with ethyl alcohol for 24 h to remove the impurities and dried it under a vacuum (60 °C) for 3 h. All the synthesis reagents (methacrylic anhydride, salicylic acid, dimethylaminopyridine (DMAP), dichloromethane, triethylamine, magnesium sulfate, ethyl ether, p-dioxane, ethanol, toluene, and petroleum ether) were from Sigma-Aldrich (San Luis, MO, USA), DMEM medium, fetal bovine serum, streptomycin solution, gentamicin, HPLC acetonitrile and HPLC methanol, and distilled water were used as received Sigma-Aldrich (San Luis, MO, USA). The MTT kit was from Roche (Basel, Switzerland)