Structure of tall oil fatty acid-based alkyd resins and alkyd–acrylic copolymers studied by NMR spectroscopy

• TOFA-based alkyd resins and alkyd–acrylic copolymers were studied with NMR spectroscopy.
• The functionality of the polyol used in the alkyd synthesis affected the formed structure.
• Polyacrylate chains grafted to the double bonds and allylic sites of the TOFA.
• BA grafted to the double bonds, MMA tended to graft to the allylic position.
• Chemical drying of copolymer films occurred by an autoxidation process.

One- and two-dimensional NMR spectroscopy was used to evaluate the structure of tall oil fatty acid (TOFA)-based alkyd resins and waterborne alkyd–acrylic copolymers. An increase in the functionality of the polyol that is used in the alkyd resin synthesis was found to increase the reactivity of the polyol towards the diacid compared with the TOFA, which causes the formation of more branched and higher molar mass alkyd resin structures. During the copolymerization, polyacrylate chains were grafted to the double bonds and allylic sites of the fatty acid chains in the alkyd resin. Butyl acrylate preferentially grafted to the double bonds, while methyl methacrylate tended to graft to the allylic position. High proportions of the double bonds remaining after copolymerization were crucial to the film formation of copolymers, because the chemical drying of copolymer films occurred by an autoxidation process.

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