New Biobased Polyester Polyols With Tunable T_g Values From 4-Vinylguaiacol-Derived Monomers

Polyesters (PEs) are among the most important classes of plastics. The identification of new, biobased, and renewable sources is necessary to increase the sustainability of PEs and related materials production. Herein, we describe the synthesis of three epoxy monomers derived from 4-vinylguaiacol, a functional molecule easily obtained from biobased ferulic acid. These monomers, namely 4-epoxyguaiacol acetate, butanoate, and hexanoate, were used in ring-opening copolymerization reactions in combination with different cyclic anhydrides, promoted by simple, (organo)catalytic initiators [i.e., bis-(triphenylphosphine)iminium chloride, tetrabutylammonium bromide, 4-(dimethylamino)pyridine, and cesium acetate]. Reactions were carried out with and without solvents, allowing the synthesis of 12 new and structurally different PEs containing up to 100% renewable monomers. The obtained PEs have number-average molecular weights (M_n) in the range of 1.8-4.1 kDa, and dispersity indexes (Đ) in the range of 1.09-1.62. Only for maleic anhydride, higher M_n and Đ values were observed, likely due to side reactions involving the double bond on the anhydride backbone. Thermal analyses revealed that, depending on the PE structure, glass transition temperatures can be modulated between 0 and 78 °C, while mass analyses confirmed the presence of hydroxy-terminated polymer chains, supporting their application as low molecular-weight polyester polyols.