An efficient nonisocyanate route to polyurethanes via thiol‐ene self‐addition

Abstract

A novel and efficient strategy for the synthesis of nonisocyanate polyurethanes has been developed via thiol–ene self‐photopolymerization. An aliphatic thiol–ene carbamate monomer (allyl(2‐mercaptoethyl)carbamate, AMC) was synthesized by a one‐step synthesis procedure, from cysteamine and allyl chloroformate. The urethane group was therefore incorporated directly into the monomer precursor, avoiding the problems associated to toxic isocyanates. AMC was successfully stabilized with the radical inhibitor pyrogallol (1% wt). In addition, the use of phenyl phosphonic acid as coadditive allowed its stabilization for lower concentrations of pyrogallol (0.1% wt). AMC was directly transformed into thermoplastic polyurethane (TPU) through thiol–ene photopolymerization by UV‐irradiation at 365 nm. The obtained TPU presented semi‐crystalline nature and very high thermal stability (T5% ∼325 °C). It was found that high concentrations of pyrogallol decreased the reaction rate and final conversion of photopolymerization. © 2014 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2014, 52, 3017–3025

Poly(hydroxy urethane)s based on renewable diglycerol dicarbonate

“…However, the production of polyurethanes has remained a major concern as it involves the synthesis and use of toxic diisocyanates [1]. Several chemical routes have been developed throughout the years to avoid these issues, yet none of these pathways is currently used for the large scale production of non-isocyanate polyurethanes (NIPU) [2][3][4][5][6][7][8]. Still, the addition reaction between cyclic carbonates and amines to form poly(hydroxy urethane)s (PHU) has recently been highlighted in an increasing number of publications [9][10][11][12][13][14].…”

Non‐isocyanate polyurethanes: synthesis, properties, and applications

“…A novel strategy for the synthesis of NIPU has been developed by Calle et al via thiol‐ene self‐photopolymerization . An aliphatic thiol‐ene carbamate monomer (allyl(2‐mercaptoethyl)carbamate) was synthesized by a one‐step synthesis procedure, from cysteamine and allyl chloroformate (Scheme ).…”

Chemo‐ and stereoselective polymerization of 3‐methylenehepta‐1,6‐Diene and Its thiol‐ene modification

“…Thiol‐ene chemistry, that is, the radical or Michael addition of thiols onto double bonds, has been extensively employed in the preparation of gels, thermosets, and the postmodification of polymers, due to its quantitative conversion, rapid reaction rates, insensitiveness to ambient oxygen or water, and ready availability of an enormous range of thiols . Such modification strategy has been successfully applied to synthesize a wide array of functional polymers with well‐defined composition and microstructure .…”