Shape memory polymers chain structures

Biodegradable shape-memory polymer networks with single POSS moieties located in the center of the network chains would promote POSS crystallization even within a constraining network structure. Successful synthesis of POSS initiated poly(e-caprolactone) (PCL) telechelic diols, utilizing a POSS diol as initiator, was reported by Lee et al. [116]. The POSS-PCL diols were terminated with acrylate groups and photocured in the presence of a tetrathiol crosslinker. Scheme 1 shows the chemical reaction for the synthesis of POSS-PCL network. 

Structural concepts for tissue-compatible and biodegradable polymers, thermoplastic elastomers, and thermosets with shape memory capabilities will be introduced. Their thermal and mechanical properties and degradation behaviour will be explained. An important precondition for the shape memory effect of polymers is elasticity. An elastic polymeric material consists of flexible segments, so-called network chains, which are connected via netpoints or junctions. The permanent shape of such a polymer is determined by the netpoints. The network chains take a coil-like conformation in unloaded condition. If the polymer is stretched, the network chains become extended... 

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