Bio-based poly(δ-decalactone) is an amorphous, low glass transition temperature (T_g) material and it is an aliphatic polyester (Martello et al., ACS Macro Lett., 2011) that can be utilized as a soft segment in thermoplastic polyurethanes (TPU). We describe the synthesis and purification of low molar mass poly(δ-decalactone) diols (PdDL), as well as the synthesis and characterization of new PdDL-based TPUs. The PdDLs obtained were characterized by proton nuclear magnetic resonance (¹H-NMR) spectroscopy and matrix-assisted laser desorption ionization mass spectroscopy. Three different PdDLs were prepared and their molar masses calculated from ¹H-NMR spectroscopy were: M_n ≈ 1300, 1800 and 2700 g mol⁻¹. These three PdDLs were reacted with 4,4′-methylenebis(phenyl isocyanate) and two different chain extenders (1,4-butanediol and water), to synthesize polyester-based TPUs. The TPUs made from PdDLs with M_n of 1800 and 2700 exhibit good elastomeric properties and their T_g values are around −40 °C. With water as chain extender urea bonds were created, which gave TPUs with higher modulus, higher stress at break and lower hysteresis.

A furfural-based DOPO-containing flame retardant, 6,6′-(((methylenebis(4,1-phenylene))bis(azanediyl))bis(furan-2-ylmethylene))bis(dibenzo[c,e][1,2]oxaphosphinine 6-oxide) (MBF-DOPO), was synthesized and utilized as a co-curing agent of 4,4′-diaminodiphenyl methane (DDM) for fire-safe epoxy thermosets. For the cured epoxy resin containing 4.0% MBF-DOPO, the limiting oxygen index (LOI) reached 32.9% (with the V-0 rating in UL-94 test), and the peak heat release rate and total smoke production values were respectively decreased by 29.3% and 33.6%, compared to pure epoxy resin. Scanning electron microscopy (SEM) and Fourier transform infrared spectroscopy (FTIR) results confirmed that the furfural-based flame retardant MBF-DOPO promoted the charring formation of the epoxy matrix, which effectively isolated the gas and heat transfer during combustion and thus enhanced the fire-safety performance of the epoxy thermosets. This work provides an effective route for synthesizing a furfural-based flame retardant, which possesses great potential for application in fire-safe epoxy thermosets.