The Characteristics of the Smart Polymeras Temperature or pH-responsive Hydrogel

Hydrogels have unique swelling behaviour and three-dimensional structure and can be applied in biomedical and tissue engineering fields. Hydrogels also can be prepared by several methods. They are called as smart hydrogels as they able to undergo transitional changes in response to environmental stimuli. One of the stimuli is temperature. The temperature can create changes to the smart polymer as they have a very sensitive balance between the hydrophobic and the hydrophilic groups in their structure. Some hydrogels exhibit a separation from solution and solidification above a certain temperature. This threshold is known as the lower critical solution temperature (LCST). The other stimulus is pH which also can give effect to hydrogel in order to be further applied as drug delivery agents. The main feature of this kind of smart polymer is an ability to receive or release protons which responding to the pH changes. These polymers are polyelectrolyte where containing acid groups or basic groups. Temperature and pH responsive hydrogel is essential and currently investigated in many various applications specifically in drug delivery system due to their unique responsive characteristics. (C) 2016 Published by Elsevier B.V.