Abstract

Shape-memory polymers are a new product created by utilizingthe shape memorizing mechanism of elastomers of the polyurethane family. Thesematerials exhibit novel properties such as sensing (thermal, stress, optical,chemical), actuation, high damping, adaptive responses, super-elasticitycapability, and air permeability.

SMP undergoing deformation at highertemperatures,"retain" the deformed shape when cooled and return to theiroriginal configuration when heated above "glass transition temperature". SMP'sshould avoid "permanent deformation".

Such type of materials capable of undergoing thermal shapetransition are a division of smart or intelligent materials. Studies are conducted tosynthesize polymeric materials with one and two switching temperatures as SMP.

Introduction

SMP can be stimulated by temperature, pH (the level ofacidity or alkalinity), chemical and light. They are able to sense and respondto external stimuli in predetermined shape. Most ofthe thermally induced shape memory polymers (SMP's) have a one-way shape memoryeffect: they remember one permanent shape formed at the higher temperature,while many temporary shapes are possible at lower temperatures for which thesystems do not have any memory.

A two-way thermally induced SMP will remembertwo permanent shapes, one formed at higher temperature and one formed at lowertemperature. By thermally cycling the system, these types of polymericmaterials will take two different shapes depending on the temperature. Theseshape memory systems are engineered at the molecular level for the requiredbehavior.

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Theauthors are associated with Bannari Amman Institute of Technology