Synthesis and characterization of fully-biobased α,ω-dihydroxyl poly(limonene carbonate)s and their initial evaluation in coating applications

• Fully biobased, high molecular weight poly(limonene carbonate)s (PLCs) were made.
• These PLCs were transesterified with polyols to medium MW, end-functional PLCs.
• The resulting α,ω-dihydroxyl poly(limonene carbonate)s were turned into coatings.
• Curing of these coatings with polyisocyanates was incomplete.
• Promising curing results were obtained for polycarbonates with pendant OH groups.

α,ω-Dihydroxyl poly(limonene carbonate)s (PLCs) have been prepared by copolymerization of limonene oxide with CO2, using a β-diiminate zinc–bis(trimethylsilyl)amido complex as the polymerization catalyst, and subsequent transcarbonation reactions using various (metallo)organic catalysts/polyol systems, viz. stannous octoate, (salen)AlEt (salen = 2,2′-ethylenebis(nitrilomethylidene)diphenol) and 1,5,7-triazabicyclo-[4.4.0]dec-5-ene (TBD) as the transcarbonation catalysts, combined with 1,3-propanediol, 1,10-decanediol, isosorbide, 2-(hydroxymethyl)-2-ethylpropane-1,3-diol and pentaerythritol as the transcarbonation agents. The structure and end groups of the polymeric species in the PLCs were identified by MALDI-ToF-MS. For the first time, the α,ω-dihydroxyl PLCs were used in solvent casting and curing. Although only moderate properties were achieved so far due to incomplete curing, the fully bio-based PLCs with adequate molecular weights and glass transition temperatures are considered as promising resins for coating applications.

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