Some polymers react to their environment with conformational changes: one of these is the polymer PNIPAM, short for poly(N-isopropylacrylamide). It is water-soluble below around 32 degrees Celsius, but above this temperature it precipitates and becomes hydrophobic. This qualifies it for smart sensor applications.
But what actually happens between PNIPAM and the solvent water?
Researchers at Ruhr University Bochum, Germany, and the University of Illinois Urbana Champaign collaborated with sound production specialists from Symbolic Sound Corporation to investigate this question. Using sound representation, they were able to decipher the interaction of water molecules with PNIPAM for the first time.
They report their findings in the journal Proceedings of the National Academy of Sciences PNAS on February 4, 2026.