Thermo-responsive alternating conetworks by the Diels-Alder reaction of furan-terminated 4-armed star-shaped ɛ-caprolactone oligomers and maleimide-terminated 4-armed star-shaped l-lactide oligomers

Hydroxy-terminated 4-armed star-shaped ɛ-caprolactone and l-lactide oligomers (H4CLOn and H4LAOn) with a degree of polymerization per arm (n = 5, 10 or 15) were reacted with furfuryl isocyanate and (4-maleimidophenyl)isocyanate to produce furan- and maleimide-functionalized 4-armed star-shaped ɛ-caprolactone and l-lactide oligomers (F4CLOn and M4LAOn), respectively. The Diels-Alder (DA) reaction of F4CLOn and M4LAOn from room temperature to 40 °C in 1,2-dichloroethane produced conetworks (F4CLOn-M4LAOn) in which the two star-shaped oligomer units are alternatingly arranged. The conversion of DA reaction for F4CLOn-M4LAOn decreased with increasing n value. F4CLO10-M4LAO10 exhibited a higher degree of swelling in chloroform than F4CLO5-M4LAO5 in agreement with the difference in crosslinking density. F4CLO15-M4LAO15 dissolved in chloroform because of the insufficient crosslinking reaction. All the F4CLOn-M4LAOns exhibited endothermic peaks due to retro-DA reactions on the first heating differential scanning calorimetric scans, whereas the corresponding peaks considerably weakened on the second heating scans due to phase separation. The cut films of F4CLOn-M4LAOn (n = 5 and 10) were self-repaired by heating the partially superposed pieces at 70 °C. [Display omitted] •Conetworks where star PCL and PLA are alternatingly arranged were prepared by Diels-Alder reaction.•The conetworks exhibited better compatibility than urethane-crosslinked randomly arranged conetworks.•Phase-separation occurred by annealing the conetworks at 150 °C due to retro Diels-Alder reaction.•The arm length largely affected the Diels-Alder and retro Diels-Alder reaction behavior.•The cut films were self-repaired by heating the partially superposed pieces at 70 °C.