Aliphatic-Aromatic Polyols by Thiol-Ene Reactions

Aliphatic-aromatic polyols were synthesized by thiol-ene reactions (photochemical or thermal) using mercaptanized starting materials from bio-based compounds: limonene dimercaptan, thioglycerol, mercaptanized castor oil and isosorbide (3-mercaptopropyl) ether. Aromatic starting materials were phenols containing double bonds; ortho-allyl phenol (OAP, petrochemical-based) and eugenol (EUG, bio-based). The phenolic hydroxyl groups were blocked by alkoxylation with propylene oxide (PO) or glycidol (GLY) prior to use in thiol-ene reaction. The aromatic rings were attached to the mercaptans by reacting thiol groups with the double bonds of alkoxylated OAP (OAP-PO and OAP-GLY) and alkoxylated EUG (EUG-PO and EUG-GLY). These synthesized aliphatic-aromatic polyols were utilized for preparation of rigid polyurethane foams whose physical-mechanical properties were superior to those made only from bio-based aliphatic polyols. These rigid PU foams can be used in a wide range of applications; such as thermal insulation of freezers, buildings, pipes and storage tanks for food and chemical industries, as wood substitute, packaging materials and flotation materials.