Synthesis of Hyperbranched Polymer with Degree of Branching of Approximately 100% by Polycondensation of 2-(4-Phenoxyphenoxy)fluorenone

Abstract

ABSTRACT:An approximately 100% branched hyperbranched polymer was successfully prepared using 2-(4-phenoxyphenoxy)fluorenone as a monomer in an acidic medium. The kinetics of the model reaction between 9-fluorenone and anisole was investigated. The reaction obeyed the second-order kinetics, indicating that the first reaction, i.e., the formation of the intermediate from 9-fluorenone and anisole, is considerably slower than the second one, i.e., the reaction of the intermediate with anisole. Based on this finding, a new monomer expected to produce a 100% branched hyperbranched polymer, 2-(4-phenoxyphenoxy)fluorenone, was designed and prepared. Hyperbranched polymers have attracted considerable attention owing to their unique properties such as an intrinsic globular structure, low viscosity, high solubility, and a large number of terminal functional groups. There are many reports on the synthesis and characterization of hyperbranched polymers and their various applications such as those in blended components, photosensitive materials, nonlinear optics, and catalysts. [1][2][3][4][5][6][7][8] Hyperbranched polymers are generally characterized by a degree of branching (DB) that is theoretically approximately 50% for a polymer derived from an AB 2 monomer; this value is assumed on the basis of the equal reactivity of the B functional groups of the AB 2 monomer. 9 The approaches reported to enhance the DB include slow addition, 10 polymerization in the presence of polyfunctional core molecules, 11 use of polyfunctional AB x monomers, 12 and post-synthetic modification. 13 Although these methods improve the DB, they do not result in a 100% DB. To obtain hyperbranched polymers with a 100% DB, the first reaction step of an AB 2 monomer should activate the second reaction.14 Voit et al. have reported the synthesis of a hyperbranched polymer with a 100% DB by the polymerization of an AB 2 -type monomer in ''criss-cross'' cycloaddition with the maleimide group as the A functional group and azine groups as the two B groups. 15 Recently, Smets et al. have reported that the acid-catalyzed polycondensation of isatins or acenaphthenones with aromatic compounds yielded hyperbranched polymers with a 100% DB. 16,17 These reports prompted us to synthesize a hyperbranched polymer with an approximately 100% DB from a common ketone compound.Ordinary ketones such as fluorenone show a poor ability to undergo diarylation; HCl catalyzes the condensation of fluorenone with phenol to afford the corresponding diarylated compound in a 46% yield in 2 d.18 Yamada et al. demonstrated that the diarylation of fluorenone effectively proceeds when 3-mercaptopropionic acid (MPA) is added to the reaction mixture at 65 C. 19Therefore, we expected that the diarylation utilizing an acid with MPA could apply to the synthesis of 100% branched hyperbranched polymer.In this paper, we present the synthesis of a hyperbranched polymer with an approximately 100% DB by the polycondensation of an AB 2 monomer, 2-(4-phenoxyphenoxy)fluorenone. The model reaction of 9...

Polycondensation

“…16) (45). A kinetic study clarified that the reaction obeyed second-order kinetics, in which the first reaction, which is the formation of the intermediate from 9-fluorenone and 3mercaptopropionic acid, is considerably slower than the second one, which is the reaction of the intermediate with 3-mercaptopropionic acid.…”

“…Based on the model reaction, a hyperbranched poly(thioketal) with 100% DB was successfully prepared using 2-[4-(4-mercaptobutoxy)phenoxy]-9H-fluoren-9one as an AB 2 monomer in trifluoroacetic acid, in which the A and B 2 functionalities correspond to the thiol and 9-fluorenone groups, respectively (Fig. 17) (45).…”

Synthesis of hyperbranched polymers with controlled degree of branching

“…Thus, the model reaction between 9-fluorenone (1) and anisole (2) was first investigated in the presence of MPA in trifluoroacetic acid. 67 The reaction between 1 and 2 (0.80 equivalent) was conducted at 60 1C for 20 h in the presence of 3 mol% MPA. Figure 5 illustrates the changes in the consumption of 1 and 2 and the yield of the diarylated product of 3 with time, as determined by 1 H-NMR.…”

“…67 Synthesis of HBPs T Higashihara et al static effects (Scheme 17). [82][83][84] Furthermore, when an alcohol intermediate is formed in an acidic solution, it will rapidly react with another aromatic compound to yield a diarylated product.…”

Synthesis of a photocrosslinkable hyperbranched polyester containing methacryloyl groups by the reaction of 1,4-bis(chloromethyl)benzene with 1,3,5-benzenetricarboxylic acid followed by reaction with methacrylic acid

“…Ueda et al 13 reported on the synthesis of a HBP, with an approximately 100% degree of branching, by the polycondensation of 2-(4-phenoxyphenoxy)fluorenone. We examined [14][15][16] the synthesis of hyperbranched polyester (HBPE) epoxy resins containing methacryloyl groups (HBPE(ep)-MA), hyperbranched oxetane resin containing methacryloyl groups (HBPE(ox)-MA) and hyperbranched polyurethane containing methacryloyl groups (HBPU-MA) by the reaction of an A 2 -type monomer with a B 3 -type monomer and their photoinduced radical polymerization.…”