Photoinduced mendable network polymer from poly(butylene adipate) end-functionalized with cinnamoyl groups

A network polymer with photoinduced mending abilities was prepared from cinnamoyl-telechelic prepolymer of poly(butylene adipate), PBAC2, and a tetra-cinnamoyl linker, C4, by photodimerization. The photodimerization reaction of the cinnamoyl groups was analyzed using both ultraviolet (UV)/visible (vis) and infrared (IR) spectroscopy. In the reaction, the isomerization of the cinnamate group from the trans to the cis conformation competes with the dimerization reaction of cinnamates. The fractions of dimer and isomer populations estimated from the UV/vis spectra revealed that dimerization was the more preferred reaction at temperatures higher than the melting point of PBAC2. When a film of the network polymer was damaged by tapping, the cinnamate dimers dissociated to form cinnamate monomers due to the reversibility of the dimerization. To recover the network structure, these monomers could be dimerized once again through a photoirradiation process. These results show that cracks in the network polymer can be recovered through photoirradiation. A network polymer with photoinduced mending ability is prepared from a cinnamoyl-telechelic prepolymer and a tetra-cinnamoyl linker by photodimerization. Though the trans–cis isomerization competes with the dimerization of cinnamates, the dimerization primarily proceeds at a temperature higher than the melting point of the prepolymer. When a film of the network polymer is damaged, cinnamate dimers in the polymer are dissociated to form cinnamate monomers. These monomers can be dimerized again by photoirradiation to recover the network structure.