A study of shape memory effect in hydrogel/polyethylene glycol hybrid

• Main Author: Luke, Pennefather Pyne
• Other Authors: Huang Weimin
• Format: Final Year Project
• Language: English
• Published: 2014
• Subjects: DRNTU::Engineering
• Online Access: http://hdl.handle.net/10356/60951
• Institution: Nanyang Technological University

Shape memory hybrids are fabricated from the combining of two materials with different properties so as to achieve a desired outcome to meet a particular application. The working mechanism of shape memory hybrids is based on the dual component system – which is made up of a matrix (always elastic) and inclusion (able to alter stiffness) component. When a temporary deformed hybrid is exposed to a stimulus, it is able to recover back to its original shape. This phenomenon is known as shape memory effect. In this report, we investigate the shape memory effects of Hydrogel/Polyethylene glycol (HG/PEG) hybrid with different weight percentages of PEG present with a heating stimulus. Hybrids were fabricated using cylindrical hydrogel immersed in different concentration levels of PEG solution. After thermal analysis testing (Differential Scanning Calorimerty) was performed to the fabricated hybrids, the transition temperature of the hybrids was found. Brief experiments were carried out and results show that HG/PEG hybrids do not experience volume expansion when heated above melting temperature of hybrid. Hybrids containing high weight percentage of PEG (> ~200 wt% of PEG) showed thermo-responsive shape memory effect, while hybrids containing lower weight percentage of PEG (< 100 wt% of PEG) became hard and brittle. Hybrids despite having thermo-responsive shape memory effect was not able to show any sign of two-way shape memory effect. This creates a new insight of the potential of hydrogel as a matrix component to provide elastic energy to HG/PEG hybrid for shape memory effects. For future studies, the use of different inclusion component (e.g. Poloxamer 407) with hydrogel matrix to test cooling response of the hybrid, can be conducted.