Furan- and maleimide-terminated 4-arm star-shaped epsilon-caprolactone oligomers (F4CLO and M4CLO) were synthesized by the reactions of hydroxy-terminated 4-arm star-shaped e-caprolactone oligomers (H4CLO) having the degree of polymerization per one oligocaprolactone chain, n = 5 or 10 with furfuryl isocyanate and 4-(maleimidophenyl)isocyanate, respectively. Solutions of F4CLO/M4CLO or F4CLO/4,4'-bismaleimidediphenylmethane (BMI) in some organic solvents changed to gels by the Diels-Alder (DA) reaction at 50 degrees C or room temperature, which came back to solutions by the retro-DA (rDA) reaction at 80 degrees C. The thermo-reversible sol-gel process due to the DA and rDA reactions was monitored by H-1 NMR and GPC analyses. DSC and XRD analyses of polymer network formed by the DA reaction revealed that the network composed of the oligocaprolactone chain of n = 10 is semicrystalline, while that of n = 5 is amorphous. The former polymer network showed higher tensile strength and modulus than the latter. (c) 2013 Elsevier Ltd. All rights reserved.