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. Polymer Journal (2012) 44, 724–729; doi:10.1038/pj.2012.18; published online 14 March 2012