Synthesis of Hyperbranched Polyacrylates by a Chloroinimer Approach

Abstract

ethyl acrylates with methyl, dodecyl, perfluoroalkyl, siloxane, oligooxyethylene, and mesogenic ester substituents were synthesized as inimers for self-condensing vinyl polymerization (SCVP) to produce hyperbranched polyacrylates. The inimers were polymerized by atom transfer radical polymerization under a variety of conditions to produce soluble polymers with broad polydispersities (up to PDI=5.24) characteristic of hyperbranched polymers, although the isolated polymers had narrower polydispersities. The molecular weight distribution was followed as a function of time and inimer conversion for the polymerization of the mesogenic inimer. The first-order inimer conversion was linear with time. The buildup of a hyperbranched structure during the SCVP was confirmed by comparison of the error in the GPC PSt -determined molecular weights of the mesogenic polymer with those of the corresponding linear, three-arm star, and comb architectures.

Synthesis and crosslinking of hyperbranched poly(n-nonyl acrylate) to form organogels

“…Figure presents the 1 H NMR spectrum of the hyperbranched poly( n ‐nonyl acrylate) reported as Entry 1 in Table . As is typical of these hyperbranched polyacrylates, the terminal vinyl resonances appear at 5.75–6.5 ppm; the CO 2 C H 2 CHBr and C H Br resonances of the acrylate ester portion of the polymer overlap at 4.5 ppm; and the C H 2 O 2 C resonance of the n ‐nonyl ester pendant groups appear at 3.9 ppm. The backbone protons resonate in the region from 1 to 3.5 ppm, under the prominent resonances at 0.8 ppm (C H 3 ), 1.25 ([C H 2 ] 6 ) ppm, and 1.7 ppm (C H 2 CH 2 O 2 C) due to the n ‐nonyl ester pendant groups.…”

“…The backbone protons resonate in the region from 1 to 3.5 ppm, under the prominent resonances at 0.8 ppm (C H 3 ), 1.25 ([C H 2 ] 6 ) ppm, and 1.7 ppm (C H 2 CH 2 O 2 C) due to the n ‐nonyl ester pendant groups. All of the resonances are broad, as expected for a polymer, and no unique resonances are detected for the branch points; therefore, the degree of branching cannot be calculated for these hyperbranched polyacrylates by NMR spectroscopy …”

“…Because of the chemical similarity of these branched polyacrylates and their linear analogs, their 1 H and 13 C NMR spectra are nearly identical, with no unique resonances for the branch points. Nevertheless, the hyperbranched architecture is supported by the characteristically broad molecular weight distributions throughout the polymerization; by the significant underestimation in their molecular weights measured by gel permeation chromatography relative to a linear standard; and by two‐dimensional mass spectrometry characterization; however, none of these techniques are quantitative.…”

“…Therefore, SCVPs of the acrylate inimers produce hyperbranched polyacrylates with many halogen atoms throughout each molecule. We previously limited the acrylate inimer conversions to 80–90% to prevent crosslinking by inevitable radical–radical coupling . The high concentration of halogen atoms throughout the hyperbranched structure should provide an ideal route for crosslinking these polymers by radical–radical coupling reactions to prepare crosslinked systems such as gels.…”

Ultrafast preparation of branched poly(methyl Acrylate) through single electron transfer living radical polymerization at room temperature

“…The first preparation of branched vinyl polymers is the self-condensing vinyl polymerization (SCVP) of an inimer, which contains both a potential initiating site and a vinyl group [5]. A number of branched vinyl polymers have been prepared through SCVP of inimer via nitroxide radical mediated radical polymerization [6,7], atom transfer radical polymerization (ATRP) [8][9][10][11][12][13][14][15][16][17][18], and reversible addition-fragmentation chain transfer polymerization [19][20][21]. However, these controlled radical polymerizations are usually time-consuming processes due to their relatively lowradical concentration.…”