Similarities between homopolymers and triblock copolymers derived from poly(ε-caprolactone) (PCL) macrodiols (HOPCL–E–PCLOH and HOPCL–PEG–PCLOH) and their poly(ester-ether-urethanes): synthesis and characterization

Ether group (E) diols [HO(CH2CH2O)xH, x = 2, 3, 4, 5, 6, and 8] and polyethylene glycol (PEG) [HO(CH2CH2O)xOH] were used as initiators in the ring-opening polymerization (ROP) of ε-caprolactone (CL) catalyzed by ammonium decamolybdate to synthesize the poly(ε-caprolactone) (PCL) macrodiols such as HOPCL–E–PCLOH and HOPCL–PEG–PCLOH, respectively. The effect of E or PEG on the crystallinity of the PCL segments (xPCL) in HOPCL–E–PCLOH homopolymer and HOPCL–PEG–PCLOH triblock copolymer was evidenced, respectively, where a weight percent of E or PEG was inversely proportional to the xPCL; this effect was explained due to that the ether segments are causing a partial disruption on the crystalline domain of PCL. A couple of species of poly(ester–ether–urethanes) (PEU) derived from HOPCL–E–PCLOH and HOPCL–PEG–PCLOH with 1,6-hexamethylene diisocyanate (HDI) were prepared, and these PEU showed an elastomeric behavior. Comparing two samples of PEU prepared from E (MW = 370 g/mol) (PEUE) and PEG (Mn = 408 g/mol) (PEUPEG), a parallel profile of their mechanical properties was seen. Eventually, HOPCL–E–PCLOH and HOPCL–PEG–PCLOH species showed similarities in terms of crystallinity and elastomeric behavior from their PEU derivatives. In addition, HOPCL–E–PCLOH and HOPCL–PEG–PCLOH and PEU samples were characterized by 1H NMR, FT-IR, GPC, DSC, and mechanical properties. Hence, homopolymers and triblock copolymers derived from PCL macrodiols with E or PEG segments, respectively, and their PEU had similarities in terms of chemical structure and physical properties