Bio‐based hydrophobic epoxy‐amine networks derived from renewable terpenoids

Abstract

ABSTRACTCarvacrol and p‐cymene are sustainable and versatile starting materials for the preparation of hydrophobic monomers. These molecules can be readily derived from pine resin or produced from other sustainable feedstocks via a biosynthetic approach. A hydrophobic epoxy monomer [bis(2‐isopropyl‐5‐methyl‐4‐(oxiran‐2‐ylmethoxy)phenyl)methane, 3] with methyl and isopropyl substituents on the aromatic rings was synthesized from carvacrol. A bisaniline [4,4′‐methylenebis(5‐isopropyl‐2‐methylaniline, 4] was then synthesized from p‐cymene. Using a cured epoxy‐amine network prepared from the diglycidyl ether of bisphenol A (DGEBA) and 4,4′‐methylenedianiline (MDA) as a baseline system, three additional networks were prepared from DGEBA:4, 3:MDA, and 3:4. The cured epoxy‐amine networks were tested for moisture uptake as well as changes in thermomechanical properties after exposure to boiling water for several days. Incorporation of the bio‐based monomers resulted in up to 53% lower water uptake compared to the baseline system. The bio‐based resins also showed greater resistance to degradation under hot‐wet conditions, with wet‐TG knockdowns as low as 8% as compared to a 19% decrease for the baseline system. These results show that the unique functionality of the renewable bisphenol and aniline used in this study can result in materials with improved hot/wet performance as compared to conventional thermosetting resins. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016, 133, 43621.