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Wednesday, February 19 • 1:00pm - 1:30pm
The Sidney Lauren Memorial Lecture - Non-Isocyanate Polyurethane Coatings Cured Via Azido-Alkyne Cycloaddition

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Conventional polyurethane/polyurea polymers are crosslinked by reaction of a polyisocyanate compound with a polyol of the polyester, polyether, or polyacrylic type.  Polyurethanes offer superior mechanical properties, especially abrasion resistance, good chemical resistance, and excellent weatherability (aliphatic isocyanates only), and are used in many high-performance polymer applications, including coatings, adhesives, flexible and rigid foams, and solid elastomers. For many of these products, particularly coatings and foams, the presence of free isocyanate groups in the uncured composition is a safety and health concern due to the toxicity of isocyanates; thus, there is interest in non-isocyanate polyurethane/polyurea (NIPU) polymers that can be crosslinked by alternative chemistries.  Our research group has developed a series of NIPU polymers for coatings that cure by azide-alkyne cycloaddition.  Commercial polyisocyanate resins based on trimers of hexane diisocyanate, including allophanate (e.g. Desmodur® XP2580), isocyanurate (e.g. Desmodur N3300), and biuret (e.g. Desmodur N3200) were reacted with propargyl alcohol to produce polyurethane resins with propargyl functionality.  Various polyols, including polyether (PPG 1000), polyester (Desmophen 650), and polyacrylic (Setalux DA870) types were modified to convert their hydroxyl functionality to azide functionality.  The best performance was obtained with an alkyne component based on Desmodur XP2580 and an azidated polyol based on Setalux DA870.  Clear, high-solids two-component coatings were formulated with and without Cu(I) catalyst, employing about 5-10 wt% n-butyl acetate for final viscosity reduction.  The coatings were drawn down on steel panels (6 mils wet), the solvent was allowed to flash, and then the films were cured for 4 h at 100° C. Coating performance properties such as pencil hardness, MEK double rubs, and glass transition temperature were comparable to a conventional polyurethane control coating made from the precursor resins.  Azido-alkyne formulations in the presence of copper catalyst with reducing agent exhibited faster curing kinetics than the polyurethane control.

Speakers
avatar for Robson Storey

Robson Storey

Professor, School of Polymer Science and Engineering, The University of Southern Mississippi, University of Southern Missisisippi
Short CourseWelcome & Course OverviewFundamentals of Polymer Design for Waterborne CoatingsThis introductory lecture discusses the general features of polymers used in waterborne coatings, and how these polymers differ from polymers used in traditional solventborne coatings. Various... Read More →



Wednesday February 19, 2020 1:00pm - 1:30pm
Rhythms Rooms I - III