Synthesis And Characterization Of Poly(Vinylcaprolactam) Copolymers

Poly(Vinylcaprolactam)(PNVCL) is low-toxicity, temperature-responsive, biocompatible, and biodegradable. Its lower critical solution temperature (LCST) can be adjusted by changing the length of the polymer and the concentration of the solutions. It is widely applied in biomedicine fields.Beta-Cyclodextrin(β-CD) is low-toxicity, stable, molecular recognition and biocompatible, which is widely applied.Poly(Vinyl-2-pyrrolidone)(PVP) is authorized as E1201 by FDA, which is low-toxicity, water-soluble and biocompatible.Poly(Vinylcaprolactam) with alkynyl functional groups(PNVCL-≡), and Poly(Vinyl-2-pyrrolidone)(PVP-N3) with azide groups,were successively synthesized by free radical polymerization and esterification reaction; Beta-Cyclodextrin with azide groups(N3-β-CD) was synthesized by esterifi cation reaction; Poly(Vinylcaprolactam)-Beta-Cyclodextrin(PNVCL-β-CD) and Poly(Vinylcaprolactam)-block-Poly(Vinyl-2-pyrrolidone)(PNVCL-b-PVP) were synthesized by click chemistry. The structures of the copolymers were confirmed by IR, 1H NMR, and the molar mass and its distributions were determined by gel permeation chromatography (GPC).The fluorescence technique was used to determine the critical micelle concentrations (CMC) of Poly(Vinylcaprolactam)-Beta-Cyclodextrin micelles solutions, which were in a range of 0.07mg/mL to 0.33mg/mL. And with the increasing of the proportion of PNVCL segments, CMC of copolymer solutions reduced. On the other hand, the UV-Vis measurement showed that these two copolymers, PNVCL-β-CD and PNVCL-b-PVP, exhibit a reproducible temperature-responsive behavior with a lower critical solution temperature (LCST) that was tunable by the block composition. The factors affected the lower critical solution temperature (LCST) of the copolymers were studied by UV-Visible analyses.