Linear polybiurets: Facile synthesis and characteristic properties

Abstract

Linear polybiurets have been synthesized by polyaddition of benzyloxyamine and diisocyanates, and properties of the novel polymeric materials have been elucidated. Prior to polymerization, model reactions between benzyloxyamine and phenyl isocyanate were examined in detail and proved to be controlled by the molar ratio of reagents and by catalysts to give the urea (1:1 adduct) and/or biuret (1:2 adduct). Under appropriate conditions, the biuret was synthesized in a quantitative yield. Polymerization of equimolar amounts of benzyloxyamine and diphenylmethane or hexamethylene diisocyanate proceeded smoothly to give polybiurets with inherent viscosities up to 0.52 dL/g. The benzyl group of the model biuret and polybiuret could be removed by catalytic hydrogenation. Both the N‐benzyloxy‐type and N‐hydroxy‐type polybiurets showed excellent solubility in common organic solvents. The two kinds of polybiurets as well as model biurets adsorbed metal cations efficiently. The N‐hydroxybiuret structure exhibited particularly high affinity for iron(III) and was useful for selective removal of iron from metal cation mixtures. © 1996 John Wiley & Sons, Inc.

1,3,5-Tri-p-tolylbiuret

“…The biuret linkage is important in preparing novel types of polymeric materials as a urea-related connecting block for building the polymer chain. Polybiurets are soluble due to intramolecular hydrogen bonding weakening intermolecular interactions, but polyureas show poor solubility due to strong intermolecular hydrogen bonding (Kurita et al, 1996). The crystal structure of 1,5-diphenylbiuret-N-cyano-N H -phenylurea has been reported (Yang et al, 1996).…”

Nanobiopolymers Fabrication and Their Life Cycle Assessments

“…[88] Owing to the high molecular regularity and rigidity, chitin tends to form molecular and intermolecular hydrogen bonds, and thus go far towards crystallization under natural condition. [89][90][91] Based on the results obtained from the X-ray diffraction, Rudal [92] proposed three distinct crystal forms of the chitin, i.e., α-, β-, and γ-chitin crystals. All these crystals are formed and are stabilized by the intensive hydrogen bond networks, but with different molecular stacking.…”