Synthesis and Characterization of All Renewable Resources Based Branched Polyester: Poly(2,5-furandicarboxylic acid-co-glycerol)

Condensation of all renewable resources based monomers 2,5-furandicarboxylic acid and glycerol in the presence of 2？mol% Sb2O3 catalyst at 210°C gives a branched polyester resin in 70% yield. This resin was characterized by elemental analysis, 1H, 13C NMR, FT-IR, and TGA-DTG. 1. Introduction The growing concern about declining fossil fuel reserves has stimulated recent interests in explorations for renewable resources based fuels as well as platform chemicals for the chemical and polymer industries. Furan compounds derived from renewable carbohydrates are a major class in this new generation of platform chemicals, and 2,5-furandicarboxylic acid (FDCA, 1) (Figure 1) is a particularly interesting compound in this group [1–3]. 2,5-Furandicarboxylic acid is the symmetrical diacid resulting from the oxidations of both primary alcohol and aldehyde groups of 5-hydroxymethylfurfural (HMF) [4] to carboxylic acid groups. This is probably the most important derivative of HMF; this symmetrical aromatic diacid has been looked as a potential replacement and the renewable resources based equivalent of terephthalic acid [5], which is a monomer in polyethylene terephthalate (PET) plastics. Furthermore, FDCA is listed in a 2004 US Department of Energy National Renewable Energy Laboratory (NREL) report [6] as one of the twelve building blocks that can be subsequently converted to a number of high-value bio-based chemicals or materials. There are a number of recent reports on the use of FDCA for the preparation of linear polyesters [1, 7] using a variety of polyesterification techniques. The widely used methods involve the use of 2,5-furandicarboxylic acid dichloride, trans-esterification, and interfacial polycondensation [7, 8]. The most commonly studied diol is the ethylene diol [5, 7, 8], but linear polyesters have been prepared by using a number of other diols like 1,3-propane diol [7], 1,4-butane diol [9], 1,6-hexane diol [9], 1,8-octane diol [9], D-isosorbide [10], D-isoidide [10], bis(2,5-hydroxymethyl)-furan [7], bis-(1,4-hydroxymethyl) benzene [7], and hydroquinone [7] as well. The polyester prepared using ethylene diol is probably the most appealing, and Gandini et al. have shown that this renewable resources based equivalent of PET has many properties comparable with PET [5]. Figure 1: Synthesis of poly(2,5-furandicarboxylic acid- co-glycerol) ( 3). 2,5-Furandicarboxylic acid (1) can be prepared by oxidation of 5-hydroxymethylfurfural (HMF) with some common stoichiometric oxidation reagents [1, 4]. Then, there are a number of reports [1] on catalytic oxidation