Polycyclotrimerization of Diynes:  Synthesis and Properties of Hyperbranched Polyphenylenes

Abstract

Diyne polycyclotrimerizations initiated by transition-metal catalysts afforded hyperbranched polyphenylenes, which exhibited low viscosity, outstanding thermal stability, and small optical dispersion. Under optimized reaction conditions, polycyclotrimerizations of 1,8-nonadiyne (1) and 1,9-decadiyne (2) catalyzed by TaCl 5-Ph4Sn produced hyperbranched poly(1,2,4-benzenetriyl-1,5-pentanediyl) (3) and poly-(1,2,4-benzenetriyl-1,6-hexanediyl) (4), 1-5 respectively, in high yields (up to 93%). The polymers were completely soluble and film-forming, and possessed high molecular weights (Mw up to ∼1.4 × 10 6 ) but low intrinsic viscosities ([η] down to 0.13 dL/g). Their structures and properties were analyzed and evaluated by IR, UV, NMR, SEC, TGA, DSC, spectrofluorometry, light scattering, and spectroellipsometry. The structural characterizations confirmed the expected hyperbranched molecular architectures of 3 and 4 (comprising of 1,2,4-benzene rings and R,ω-alkyl spacers) and revealed the regioselective feature of the diyne polycyclotrimerizations. Polymers 3 and 4 underwent glass transitions at 43 and 23 °C, respectively, and lost almost no weights when heated to ∼500 °C. Polymer 3 emitted UV light upon excitation, whereas 4 was practically nonluminescent. The thin films of 3 were highly transparent (g99.5% transmittance) and displayed an optical dispersion as low as 0.009 in the visible spectral region, much superior to those of the commercially important "organic glasses" such as poly(methyl methacrylate) and polycarbonates.

Hyperbranched Acrylate Copolymer via Initiator‐Fragment Incorporation Radical Copolymerization of Divinylbenzene and Ethyl Acrylate: Synthesis, Characterization, Hydrolysis, Dye‐Solubilization, Ag Particle‐Stabilization, and Porous Film Formation

“…Figure 6 shows the composition of the copolymers formed at 70 and 80 8C at different times, where the concentrations of DVB, EA, and MAIB were 0.10, 0.50, and 0.50 mol Á L À1 , respectively. With respect to the copolymers formed at 70 8C, the fraction of the DVB unit with intact double bonds decreased reasonably from 8 mol-% (15 min, run 19) to zero over 45 min (runs [23][24][25]. That of the DVB unit with no double bond also decreased from 32 to 15 mol-% with time up to 40 min and leveled off.…”

“…[18][19][20][21][22][23][24][25][26] We also examined viscometrically at 30 8C a benzene solution of the same copolymer as subjected to the MALLS measurements. Figure 7 presents the relationship between the reduced viscosity (Z red ) and the copolymer concentration (C).…”

“…Temperature The observed results are also shown in Table (runs [11][12][13][14][15][16][17][18][19][20][21][22][23][24][25][26][27].…”

Aromatic Hyperbranched Polymers: Synthesis and Application

“…The polymers are synthesized utilizing Diels-Alder cycloaddition [228] of phenylated cyclopentadienones with phenylated alkynes and subsequent decarbonylation leading to hb structures with high thermal stability and better processability. Previously, Tang and colleagues prepared hb-PPhs using diyne polycyclotrimerization initiated by transition metal catalysts [229] and base-catalyzed alkyne polycyclization [230].…”

Stimulus responsive fluorescent hyperbranched polymers and their applications

“…We coined it "aggregation-induced emission" (AIE) [29]. Then, with these new AIE molecules, we successfully synthesized hyperbranched polymers via polycyclotrimerization [30] which show enhanced light emission when in aggregation and we named it "aggregation-enhanced emission" (AEE) [31,32]. AEE (AIE) completely surmounts the chronic barrier and may lead to more novel applications with FHBPs.…”