Synthesis and Photo‐initiated Radical Polymerization of Methacrylates Derived from Bio‐based ω‐Hydroxycarboxylic Acids

The bio‐based methacrylates 9‐(methacryloyloxy)‐10,18‐dihydroxyoctadecanoic acid/9,18‐dihydroxy‐10‐(methacryloyloxy)octadecanoic acid isomer mixture and 22‐methacryloyloxydocosanoic acid were synthesized from 9,10‐epoxy‐18‐hydroxyoctadecanoic acid and 22‐hydroxydocosanoic acid. The white crystalline 9,10‐epoxy‐18‐hydroxyoctadecanoic acid and cream‐colored 22‐hydroxydocosanoic acid were isolated from both bark of Betula pendula and cork of Quercus suber after extraction of the milled plant materials with methanol, treating the insoluble residues with 2‐propanole containing suspended sodium hydroxide, application of a working up procedure developed in this work for the resulting mixture, and purification of the products obtained. The new bio‐based methacrylates show higher reactivity in the photoinitiated polymerization in comparison with the commercial laurylmethacrylate as detected by photo‐DSC. For comparison, traditional free radical polymerization of the new bio‐based methacrylates was carried out in dimethylsulfoxide using 2,2’‐azobis‐(2‐propionitrile) as initiator. Furthermore, quantitative conversion of the bio‐based monomers during the photoinitiated polymerization makes these bio‐based monomers interesting for application in coatings. As expected, the photopolymer made from the 9‐(methacryloyloxy)‐10,18‐dihydroxyoctadecanoic acid/9,18‐dihydroxy‐10‐(methacryloyloxy)octadecanoic acid isomer mixture is amorphous. Interestingly, the photopolymer made from the 22‐methacryloyloxydocosanoic acid contains crystalline structures as detected by DSC investigation.This article is protected by copyright. All rights reserved.