polyNvinylcaprolactam

PolyNvinylcaprolactam, more properly called poly(N-vinylcaprolactam) (PNVCL), is a synthetic polymer derived from the monomer N-vinylcaprolactam. In aqueous solution, PNVCL exhibits thermoresponsive behavior with a lower critical solution temperature (LCST) near body temperature, typically around 30–40°C depending on molecular weight and formulation. Below the LCST, PNVCL is hydrophilic and well-solvated; above the LCST, it becomes hydrophobic and undergoes reversible phase separation, enabling applications such as controlled drug release and the formation of hydrogels and micelles.

PNVCL is prepared primarily by free-radical polymerization of NVCL, using initiators such as azobisisobutyronitrile (AIBN) or redox systems in water or polar solvents. Polymerization can be performed under bulk, solution, or emulsion conditions, and can be controlled by reversible-deactivation radical polymerization methods (RAFT, ATRP) to tailor molecular weight and dispersity. Copolymerization with other monomers (e.g., acrylamide, acrylic acid, or compatible monomers) allows tuning of LCST, hydrophilicity, and biodegradation potential.

PNVCL is a non-ionic, water-soluble polymer at ambient conditions with a tunable LCST that shifts with molecular weight, concentration, solvent composition, and salt content. The polymer is reported to be biocompatible and to exhibit relatively low cytotoxicity. It is not readily biodegradable; hydrolytic degradation is slow under physiological conditions, which influences long-term applications.

Applications include drug delivery as a thermoresponsive vehicle, injectable hydrogels, tissue engineering scaffolds, and surface coatings that respond to temperature changes. PNVCL can form physical gels through temperature-triggered association or covalently crosslinked networks for controlled release systems.