2025/01/06 by Morgan P. Le Dû, Julija Reitenbach, David P. Kosbahn +6 · 1 voice
Biochemistry, Genetics and Molecular Biology · Chemistry · Engineering · #Advanced Polymer Synthesis and Characterization #Advanced Sensor and Energy Harvesting Materials #Hydrogels: synthesis, properties, applications
paper · doi:10.1021/acs.macromol.4c02802
openalex publication_date 2025/01/06 · openalex created_date 2025/01/07 · openalex updated_date 2026/08/01
High Resolution Image Download MS PowerPoint Slide 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, N 2 -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.