Synthesis of Biorenewable Starch–Farnesene Amphiphilic Conjugates via Transesterification of Terpene-Derived Diels–Alder Adducts

Abstract

Herein we describe a new class of terpene-starch esters synthesized from biorenewable building blocks. Although our work is specific to starch, we believe the synthetic methodology can be extended to a wide range of polysaccharide substrates. In our approach, an ester functionality is first introduced to the farnesene backbone via high yielding, solvent-free Diels–Alder chemistry. The farnesene esters are subsequently transesterified with starch to produce a range of starch–farnesene amphiphilic biopolymers. The key transesterification reaction between farnesene and starch employs 1,5,6-triazabicyclo[4.4.0]dec-5-ene (TBD) as a guanidine base organocatalyst and is capable of producing materials with a high degree of substitution (DS). The DS can be modulated by altering the starch/farnesene feed ratio. Low DS starch–farnesene esters show surfactant-like properties while the higher DS materials were successfully solvent-cast into standalone films. Thermal and mechanical tests reveal starch–farnesene esters ...