| 초록 |
Shape memorizing polymers are of great interests. These polymers have to remember their original shapes and should not deform permanently when they are deformed. In many examples, polymers are crosslinked at temperatures above their melting temperature so that interconnecting chains have the most random conformations. Elongation at high temperatures followed by cooling below the melting or glass transition temperature set the deformed shape of the polymers. When the deformed polymers are re-heated, the interconnecting chains retain their original random conformation and the polymers recover their original shapes. In thermoplastic shape memorizing polymers, the polymer chains have hard and soft segments that function as crosslinkers and interconnecting chains, respectively. In other examples, polymers are synthesized with groups that crystallize by strain to set the deformed shapes of polymers. All these polymers are designed carefully for shape memorizing characteristics. To our best knowledge, there is not known example of shape memorizing polymer that inherently have shape memorizing properties. In this report, we will describe inherent shape memorizing properties of some bacterial poly(3-hydroxybutyrate-co-3-hydroxyvalerate) biosynthesized by Pseudomonas sp. HJ-2. This polymer is deformed at room temperature and return to its original shape above 80oC. The changes accompanied by deformation and recovery will be discussed with results of XRD and DSC. |
