Influence of pressure on the state of poly(N-isopropylacrylamide) and poly(N,N-diethylacrylamide) derived polymers in aqueous solution as probed by FTIR-spectroscopy

✍ Scribed by Matthias Pühse; Martina Keerl; Christine Scherzinger; Walter Richtering; Roland Winter

• Publisher: Elsevier Science
• Year: 2010
• Tongue: English
• Weight: 700 KB
• Volume: 51
• Category: Article
• ISSN: 0032-3861
• DOI: 10.1016/j.polymer.2010.06.011

✦ Synopsis

We investigated the hydration and swelling properties of poly(N-isopropylacrylamide) and poly(N-isopropylacrylamide)-poly(N,N-diethylacrylamide) derived microgels by Fourier transform infrared-(FTIR-) spectroscopy in a wide region of the temperatureepressure plane. These systems are known to show a swollen-to-collapsed-transition upon temperature elevation. Our data reveal that pressure favours the swollen, hydrated state over the collapsed state in all systems investigated. A detailed analysis of the fractions of the respective IR sensitive amide-I 0 -subbands allowed the calculation of DG o and DV o for the pressure-induced swelling process as well as evaluation of various intra-and intermolecular hydrogen bonding connectivities in the different systems. In fact, considerable differences exist between different polymer or microgel types with regards to their hydrogen bonding pattern as a function of temperature and pressure, and the microgels may even exhibit a biphasic swelling behavior. Notably, the thermodynamic parameters derived reveal to be in the same order of magnitude as measured for the pressure and cold denaturation of proteins.