ABSTRACT
The cold hibernated elastic memory (CHEM) self-deployable structure technology utilizes segmented polyurethane-based thermoplastic shape memory polymers (SMP). The segmented polyurethanes are an important class of multiblock copolymers made of long linear chain consisting of two types of connected segments. They are comprised of alternating sequences of diisocyanate with glycol chain extender-based elastic, relatively hard segments and polyol (hydroxy-polyether or hydroxyl-polyester)-based soft segments. By selecting a proper diisocyanate and polyol combination and/or soft-to-hard segment ratio, one can tailor the required properties such as elasticity, glass transition temperature, and melting point. The molecular structure and thermo-physical behavior are the reasons the segmented polyurethanes under certain conditions have the ability for shape memory effect (SME). The fundamental mechanism of SME in SMPs, that is broadly described in Chapter 3, is a dual-segment system in which one segment is always elastic within the whole application range and the other is transitional in the presence of the right stimulus.
