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Significant strides in the development of non-isocyanate polyurethane (NIPU) have been made in the coatings industry. Aligned with green chemistry principles, this study explores the use of bio-based, low volatile organic compounds and fast-curing waterborne NIPU for coating applications. The linseed oilbased cyclic carbonate was synthesized via a thiol–ene click reaction and was followed by an esterification reaction directly from linseed oil. In this structure, the cyclic carbonates are introduced as pendant functional groups to accelerate the curing. Next, a series of linseed oil-based waterborne NIPUs were synthesized and developed from the linseed oil-based cyclic carbonate, a bio-based fatty acid diamine, and an internal dispersion agent. Different formulations of the linseed oil-based NIPU coatings were designed by varying the internal dispersion agent content and urethane content, and a solvent-borne NIPU was included in the study for comparison purposes. The NIPU coatings with different formulations achieved a broad range of thermal stabilities, viscoelastic properties, and mechanical properties. The general coating properties—including hardness, solvent resistance, impact resistance, and adhesion—were evaluated to demonstrate the practical application of the waterborne NIPU in coatings. The linseed oil-based waterborne NIPU coatings exhibited performance comparable to both a solvent-borne NIPU coating and a commercial waterborne isocyanate-based polyurethane coating.
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3D printable non-isocyanate polyurethanes with tunable material properties
Green chemistry-based non-isocyanate polyurethanes (NIPU) are synthesized and 3D-printed via rapid, projection photopolymerization into compliant mechanisms of 3D structure with spatially-localized material properties. Trimethylolpropane allyl ether-cyclic carbonate is used to couple the unique properties of two types of reaction chemistry: (1) primary diamine-cyclic carbonate ring-opening conjugation for supplanting conventional isocyanate-polyol reactions in creating urethane groups, with the additional advantage of enabling modular segment interchangeability within the diurethane prepolymers; and (2) thiol–ene (click) conjugation for non-telechelic, low monodispersity, quasi-crystalline-capable, and alternating step-growth co-photopolymerization. Fourier transform infrared spectroscopy is used to monitor the functional group transformation in reactions, and to confirm these process-associated molecular products. The extent of how these processes utilize molecular tunability to affect material properties were investigated through measurement-based comparison of the various polymer compositions: frequency-related dynamic mechanical analysis, tension-related elastic-deformation mechanical analysis, and material swelling analysis. Stained murine myoblasts cultured on NIPU slabs were evaluated via fluorescent microscopy for “green-chemistry” affects on cytocompatibility and cell adhesion to assess potential biofouling resistance. 3D multi-material structures with micro-features were printed, thus demonstrating the capability to spatially pattern different NIPU materials in a controlled manner and build compliant mechanisms.
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- PAR ID:
- 10113747
- Date Published:
- Journal Name:
- Polymer Chemistry
- Volume:
- 10
- Issue:
- 34
- ISSN:
- 1759-9954
- Page Range / eLocation ID:
- 4665 to 4674
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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- Free Publicly Accessible Full Text
-
Accepted Manuscript1.0
- Journal Article:
- https://doi.org/10.1039/C9PY00999J
