Poly(N-isopropylacrylamide) (PNIPAM) is a temperature-responsive polymer used in biomedical research applications. PNIPAM undergoes a reversible, lower critical solution temperature (LCST) phase transition when heated above 32 °C, transitioning from a soluble to an insoluble material. PNIPAM is also frequently crosslinked to yield hydrogels with reversible, thermal shrinking and swelling. Poly(N-isopropylacrylamide) is also readily functionalized and has been used as the hydrophilic block in the synthesis of thermoresponsive, amphiphilic block copolymers. Due to the similarity in temperature between the LCST of PNIPAM and the temperature of the human body, PNIPAM materials have been frequently utilized in tissue engineering and controlled drug delivery research applications.

PNIPAM can be used in the formation of a smart hydrogel, which finds potential usage in sensors, fuel cells, supercapacitors, and lithium-ion batteries. It can also be used in the fabrication of molecular nanothermometer. PNIPAM is coated with gold nanoparticles (AuNPs) to form microgels that facilitate highly reproducible signals for surface-enhanced Raman scattering (SERS).

Thermosensitive polymer, can be used to form a hydrogel. Aqueous polymer solution undergoes a phase transition from a soluble to an insoluble state when the temperature is raised to ca. 32 °C.