Novel, linear, high-molecular-weight single-strand heteroaromatic polymers and copolymers containing 9H-xanthene moieties in the backbone were synthesized by metal-free superacid-catalyzed stoichiometric and nonstoichiometric step-growth polymerizations of carbonyl compounds bearing electron-withdrawing substituents with bisphenols. The electrophilic aromatic substitution reactions of ketones with phenol fragments occur exclusively in ortho-positions to the hydroxy phenol group and followed by highly efficient cyclodehydration reaction of hydroxyl-containing intermediates to give corresponding substituted 9H-xanthene-2,7-diyl polymers. The polymerizations were performed at room temperature in the Brønsted superacid trifluoromethanesulfonic acid (CF 3 SO 3 H, TFSA) and in a mixture of TFSA with methylene chloride and nitrobenzene.
A novel series of linear, high-molecular-weight polymers and copolymers were synthesized by one-pot, metal-free superacid-catalyzed polymerization of aliphatic 1,2-diketones (2,3-butanedione (1a), 2,3-hexadione (1b), 3,4-hexadione (1c), 2,3-butanedione monoxime (1d), pyruvic acid (1e), 1,4-dibromo-2,3-butanedione (1f), 2-bromopyruvic acid (1g), and methyl-3,3,3-trifluoropyruvate (1h) with linear, nonactivated, multiring aromatic hydrocarbons terphenyl (A), biphenyl (B), fluorene (C), and N-ethyl carbazole (D). Depending on the reaction system, the polymerizations were carried out as stoichiometric or non stoichiometric, with direct or inverse monomer addition. Copolymers were obtained by polymerization of 1,2-diketones with a mixture of aromatic hydrocarbons. In the course of the polymerization only one carbonyl group of a 1,2-diketone reacts to form C−C bonds with aromatic fragments while the other functional groups (including the second carbonyl group) are incorporated unchanged into polymer chain. The polymerizations performed at room temperature in the Brønsted superacid CF 3 SO 3 H (TFSA) and in a mixture of TFSA with methylene chloride or trifluoroacetic acid (TFA) tolerant of carbonyl, acetyl, N-oxime, carboxy, methoxy, and bromomethyl groups. The polymers obtained were soluble in most common organic solvents, and flexible transparent, colorless films could be cast from the solutions. 1 H and 13 C NMR analyses of the polymers synthesized revealed high regio-selectivity of the polymerizations and yielded linear structures with para-substitution in the phenylene fragments of the main chains. An electron affinity (EA) of the carbonyl component and the heterolytic C−O bond dissociation energy (DE) in carbinol 3 (correlating with the activation energy of carbocation 4 formation) have been used to rationalize the reactivity of carbonyl components. The calculations show the following reactivity order of the diketones. 1f > 1g ≈ 1e> 1a> 1d > 1h> 1b>1c which is totally in agreement with the experimental data. The new functional polymers obtained demonstrate good processability, high T g and thermal stability. Unexpected white light emission was observed for polymer 2gA.
Metal nanoparticles have unusual optical, electronic, sensing, recognition, catalytic, and therapeutic properties. They are expected to form the basis of many of the technological and biological innovations of this century. A prerequisite for future applications using nanoparticles as functional entities is control of the shape, size, and homogeneity of these nanoparticles and of their interparticle spacing and arrangement on surfaces, between electrodes, or in devices. Here, we demonstrate that thin films of gold, silver, and copper sputter-deposited onto the surface of an organic polymer poly[[1,1':4',1″-terphenyl]-4,4″-diyl(2-bromo-1-carboxyethylidene)] (PTBC) undergo spontaneous solid-solid transformation into nanoparticles. Furthermore, we show that, by varying the thickness of the films, the volume-to-surface ratio of the polymer substrate, and the amount of plasticizer, it is possible to control the rate of transformation and the morphology of the nanoparticles formed. PTBC containing Au nanoparticles was found to enhance the cell adhesion and proliferation. To the best of our knowledge, our findings constitute the first experimental evidence of spontaneous, room-temperature, solid-solid transformation of metal films sputtered onto the surface of an organic polymeric substrate into nanoparticles (crystals).
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.