Shape Memory Polymer

Abstract

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

SMP undergoing deformation at higher temperatures,"retain" the deformed shape when cooled and return to their original configuration when heated above "glass transition temperature". SMP's should avoid "permanent deformation".

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

Introduction

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

A two-way thermally induced SMP will remember two permanent shapes, one formed at higher temperature and one formed at lower temperature. By thermally cycling the system, these types of polymeric materials will take two different shapes depending on the temperature. These shape memory systems are engineered at the molecular level for the required behavior