Comparison of the Swelling Behavior of Poly(N-Isopropylacrylamide) and Poly(N-Vinylisobutyramide) Thin Films under Water Vapor Exposure

Morgan P. Le Dû, Julija Reitenbach, David P. Kosbahn, Lukas V. Spanier, Robert Cubitt, Cristiane Henschel, André Laschewsky, Christine M. Papadakis, Peter Müller-Buschbaum

Research output: Contribution to journalArticlepeer-review

Abstract

Poly(N-isopropylacrylamide) (PNIPAM) is known for exhibiting lower critical solution temperature behavior in water. A structural isomer of PNIPAM, the likewise LCST-type polymer poly(N-vinylisobutyramide) (PNVIBAM), is compared to PNIPAM in a thin film with respect to their swelling behaviors and water uptake kinetics in a humid atmosphere. Based on spectral reflectance, Fourier-transform infrared (FT-IR) spectroscopy, and time-of-flight neutron reflectometry, the amount and kinetics of uptaken water and its distribution inside the films correlate with molecular changes. It is observed that PNVIBAM swells less than PNIPAM. The FT-IR signals reveal a lower water affinity for PNVIBAM than for PNIPAM and larger hydrophobic clathrates in PNVIBAM, which hinders the introduction of water. Additionally, N2-dried PNIPAM films still contain primary water, whereas PNVIBAM can be fully dried. The first step of water uptake of the main layer describes a filling of the free volume, reaching a water content of 3.8% in PNVIBAM and 6% in PNIPAM.

Original languageEnglish
JournalMacromolecules
DOIs
StateAccepted/In press - 2025

Fingerprint

Dive into the research topics of 'Comparison of the Swelling Behavior of Poly(N-Isopropylacrylamide) and Poly(N-Vinylisobutyramide) Thin Films under Water Vapor Exposure'. Together they form a unique fingerprint.

Cite this