Shape Memory Polymer Systems

SMPs and related composite systems are grouped differently. The classification may consider the SM mechanisms, the morphology, the type (one-way, two-way), the activation mode (e.g., thermal, photo, chemical sensitive) among others. 

Biodegradable polymers play a prominent role in the family of SMPs. This is due to their biodegradabdity because in many of the medical applications the related devices with SM function (e.g., sutures, catheters, stents) should be present only temporarily in the human body. The other, not less important, aspect is that the switch temperature for shape programming (Tf.j. g) can well be matched with that of the body. 

Next we shall give an overview on SMP systems which are composed fully or partly from biodegradable polyesters. To give a comprehensive review is beyond our intention owing to large body of the related works available both in the open and patent literatures. On the other hand, the reader will get a structured overview of the basic strategies followed to tailor the structure and performance of SMPs in order to meet the requirements of given applications. 

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Ratna, D., and Karger-Kocsis, J. 2011. Shape memory polymer system of semi-interpenetrating network structure composed of crosslinked poly (methyl methacrylate) and poly (ethylene oxide). Polymer 52 1063-1070. 

Strained silicon wafers, in scaling to deep submicron dimensions, 22 256 Strainers, in refrigeration systems, 27 539 Strain fixity rate (R ), in testing shape-memory polymers, 22 361... 

Tobushi, H., Hashimoto, T., Ito, N., Hayashi, S., Yamada, E., 01/1998. Shape fixity and shape recovery in a film of shape memory polymer of polyurethane series. Journal of Intelligent Material Systems and Structures 9 (2), 127—136. http //dx.doi.org/10.1177/... 

Stimuli-responsive materials have sparked enormous interest in recent years due to their potential applications in micro-machines, soft robots, biomedical systems, etc. [1-6]. A variety of intelligent polymeric materials such as shape memory polymers [7, 8], polymer gels [9, 10], conducting polymers [11, 12], and dielectric elastomers [13,14] have been developed for these applications. Compared to other stimulus-driven methods including pressure [15], heat [16, 17], electric field... 

Development of Physics Based Constitutive Modeling of Shape Memory Polymers A New Evaluation System Potential Applications in Civil Engineering... 

Numerous polymers have been proposed as shape-memory polymers (SMPs), and many of them are based on polyurethanes. This is because of the intrinsic versatility of segmented copolyurethane systems. By suitable choice of diisocyanate and macrodiol, a wide variation in properties may be obtained, allowing the possibility of tuning the shape-memory response to suit different applications. Usually they are phase-segregated materials. For example, a dispersed rigid phase (usually based on the diisocyanate) provides physical crosslinks, while the macrodiol provides a soft amorphous phase with low glass transition that provides the trigger temperature for shape recovery [63]. 

The latest embodiment of an SMP clot retrieval system demonstrates a hybrid shape-memory material system. The design of SMP biomedical devices should not be limited to purely polymer-based devices but rather can be combined with other smart or active materials. Novel multifunctional SMP-hybrid systems could lead to multiple unique and novel platform technologies for future development. 

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