Enhanced mechanical properties of fatty acid-derived thermoplastic elastomers through incorporation of ionic interactions

Vegetable oils and their fatty acids are attractive resources for polymers, due to their worldwide abundance, yet the presence of long alkyl chains greatly impacts the resulting polymer properties. The incorporation of ionic interactions in the unentangled poly(n-alkyl methacrylate) midblock of a fatty acid-based thermoplastic elastomeric triblock copolymer was explored as a method of improving its mechanical properties. Poly(methyl methacrylate-b-(lauryl methacrylate-co-tert-butyl methacrylate)-b-methyl methacrylate), which exhibits low tensile strength and elongation at break, was modified by hydrolysis to form poly(methyl methacrylate-b-(lauryl methacrylate-co-methacrylic acid)-b-methyl methacrylate). The methacrylic acid group in the midblock was further neutralized with sodium hydroxide to introduce ionic crosslinks into the system. Increased relaxation time was observed by increasing ion and acid contents. The triblock copolymer mechanical properties were improved significantly by the incorporation of ionic interactions. Enhancement of mechanical properties was correlated with the relaxation time of the midblock.