pH-Induced Shape-Memory Polymers

A novel pH sensitive shape-memory polymer (SMP) is prepared by cross-linking the beta-cyclodextrin modified alginate (beta-CD-Alg) and diethylenetriamine modified alginate (DETA-Alg): The pH reversible beta-CD-DETA inclusion complexes serve as a reversible phase, and the cross-linked alginate chains serve as a fixing phase. It is shown that this material can be processed into temporary shape as we needs at pH 11.5 and recover to its initial shape at pH 7. The recovery ratio and the fixity ratio were 95.7 +/- 0.9% and 94.8 +/- 1.1%, respectively. Furthermore, this material showed good degradability and biocompatibility. Because the shape transition pH value is quite close to that of our body fluid and this pH triggered shape-memory effect is convenient and safe to use, this material has a high potential for medical application.