Thermal and mechanical properties of poly(N-isopropylacrylamide)-based hydrogels as a function of porosity and medium change

• Published in: Journal of applied polymer science Vol. 132; no. 45; pp. np - n/a
• Main Authors: Chatterjee, Prithwish, Dai, Annie, Yu, Hongyu, Jiang, Hanqing, Dai, Lenore L.
• Format: Journal Article
• Language: English
• Published: Hoboken Blackwell Publishing Ltd 05.12.2015; Wiley Subscription Services, Inc
• Subjects: Hydrogels; Materials science; mechanical properties; Media; Methyl alcohol; Polymers; Porosity; Response time; stimuli-sensitive polymers; Strength; structure-property relations; Surfactants; synthesis and processing; thermal properties; Transition temperature
• ISSN: 0021-8995; 1097-4628
• DOI: 10.1002/app.42776

ABSTRACT Poly(N‐isopropylacrylamide) (PNIPAAm) has been a well‐known stimuli–responsive material and has been used in multiple novel applications. One of the key attributes to make the hydrogel more attractive is to control the response time and temperature. This work focused on comparing the physical properties, such as response time, transition temperature, heat of fusion, and mechanical strength, of macroporous and microporous PNIPAAm hydrogels, respectively. It was found that the macroporous hydrogels synthesized from a low‐temperature polymerization with addition of tetramethyl orthosilicate exhibited a faster response time and superior mechanical strength. Furthermore, to modulate the transition temperature, both the macroporous and microporous hydrogels were subjected to different qualities of media by introducing a cosolvent (methanol) or an anionic surfactant (sodium dodecyl sulfate). Interestingly, addition of a cosolvent demonstrated a more pronounced effect on the macroporous hydrogel, whereas the surfactant resulted in a more pronounced effect on the microporous hydrogel. Such results revealed that based on their porosity; there were appreciable differences when the PNIPAAm hydrogels interacted with media molecules. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015, 132, 42776.