A novel one-pot synthesis of hyperbranched polyurethanes

Abstract

The thermal decomposition of 3,5-di hydroxybenzoyl azide, to generate in situ the corresponding AB2-type dihydroxy isocyanate monomer, was found to give hyperbranched polyurethanes, whose structures were established using IR and N M R spectroscopy.

Synthesis, characterization and properties of a hyperbranched aromatic polyamide: poly(ABZAIA)

“…have been used to prepare a wide variety of hyperbranched polymers, such as polyphenylenes, [9] aromatic polyesters, [5] polyurethanes [10,11] and aromatic polyamides. [12,13] Among them, hyperbranched aramids are very interesting, being able to retain some excellent properties of their linear homologues (e. g. heat and flame resistance), supplemented by an easier processability.…”

Dendritic Polymers Based on Urethane Chemistry – Syntheses and Applications

“…The first route, described by Spindler and Fréchet, [10] used isocyanate chemistry and guaranteed the regular structural design of a dendrimer by help of protecting group techniques. The second route, published by Kumar and Ramakrishnan [11] used the Curtius rearrangement of azides as an isocyanate free process to generate hyperbranched polyurethanes.…”

A comparative study of the structure–property behavior of highly branched segmented poly(urethane urea) copolymers and their linear analogs

“…These materials are targeted for applications that include improving the dyeability of polypropylene fibers and improving the control of the rheological behavior of paper coating dispersions. However, there are very few reports on the synthesis of hyperbranched systems utilizing the commercially important isocyanate chemistry [6][7][8][9][10][11]. Spindler and Fréchet [6] reported the first synthesis of hyperbranched polyurethanes wherein they utilized protected or blocked isocyanates.…”

“…Spindler and Fréchet [6] reported the first synthesis of hyperbranched polyurethanes wherein they utilized protected or blocked isocyanates. Later, Kumar and Ramakrishnan [7,8] produced wholly aromatic hyperbranched polymers with urethane linkages by the polymerization of 3,5-dihydroxy benzozyl azide. An important observation made by Kumar and Ramakrishnan was that the T g (measured by DSC) of the hyperbranched polymer without the oxyethylene spacer (xZ0) was 106 8C and it decreased to 13 8C when the length of the spacer was increased to xZ 2.…”