N-vinylcaprolactam, A Responsive Polymer

- Mar 26, 2019-

The n-vinylcaprolactam manufacturer introduces that living polymerization refers to the absence of chain termination and irreversible chain transfer polymerization, and active/controlled radical polymerization is one of the living polymerizations, which has the advantage of controlling the polymer. The molecular weight, narrower molecular weight distribution (same chain length), end group functionalization, etc., and wide application of monomers, low industrial cost, synthesis of polymers with novel topologies by active/controlled radical polymerization, Polymers of different compositions and functional groups attached to different parts of the polymer.

  Poly-n-vinylcaprolactam (PNVCL) is a responsive polymer with a low critical solution temperature in the physiological temperature range, which is different from the most widely studied temperature-responsive polymer, poly-n-isopropyl endenamide. The hydrolysis of poly-n-vinylcaprolactam does not produce toxic small molecular amines. Therefore, PNVCL has better biocompatibility and has broad application prospects in the field of biomedicine.

  The low critical solution temperature (LCST) of poly-n-vinylcaprolactam decreases with increasing molecular weight and aqueous solution concentration, and belongs to type I of three LCST behaviors, namely the classical Flory-Huggins temperature responsive behavior, that is, The LCST value of polyPNVCL can be adjusted by controlling its molecular weight, so it is important for the molecular weight control of PNVCL.

  However, the monomer n-vinylcaprolactam of poly-n-vinylcaprolactam can hardly be polymerized in a manner other than free radicals. To obtain PNVCL with a designed molecular weight, the only way to do this is to use active/controlled radical polymerization. .

  However, n-vinylcaprolactam is a non-conjugated monomer, and the radical species derived therefrom are very active. When combined with a reversible terminator or a reversible transfer agent, it is difficult to break, resulting in a complete shift of chemical equilibrium in favor of dormant species formation. The polymerization reaction is retarded or completely blocked. Therefore, the activity/controlled radical polymerization of n-vinylcaprolactam has been difficult. However, in recent years, atom transfer radical polymerization (ATRP), reversible addition-fragmentation chain transfer polymerization and organic cobalt-regulated radical polymerization of NVCL have been used. Great progress has been made.