Preparation of PNVCL controlling its molecular weight and maintaining low dispersities by using a trithiocarbonate RAFT agent was achieved. Typical RAFT kinetics were not observed, nevertheless the prepared polymers were reactivated to grow a second hydrophobic poly(hexyl acrylate) block. A series of statistical copolymers of NVCL with N‐vinyl pyrrolidone, n‐hexyl acrylate, methacrylic acid, 2‐(diethylamino)ethyl methacrylate and 2‐(methacryloyloxy)benzoic acid with controlled dispersity were also prepared. By this copolymerization method the cloud point temperature of PNVCL was varied from 27 °C to 42 °C depending on comonomer type, content and pH of the aqueous solution.
Thermo-responsive polymers and copolymers derivatives of oligo(ethylene glycol) methyl ether methacrylate (Mn = 300 g mol−1) (OEGMA) and di(ethylene glycol) methyl ether methacrylate (DEGMA) have been synthesized by reversible addition fragmentation chain transfer polymerization (RAFT) using 5-amino-4-methyl-4-(propylthiocarbonothioylthio)-5-oxopentanoic acid (APP) as chain transfer agent (CTA). The monomer conversion was evaluated by hydrogen nuclear magnetic resonance (1H-NMR); number average molecular weights (Mn), weight average molecular weight (Mw), and dispersity (Đ) were obtained by gel permeation chromatography (GPC); glass transition temperature (Tg) was evaluated by modulated differential scanning calorimetry (DSC), cloud point temperature (Tcp) was measured and compared by turbidimetry and dynamic light scattering (DLS). The effect of polymer composition and concentration on the Tcp, either in water or in phosphate buffer saline (PBS), was studied. The values of Tcp using PBS were between 3 and 4 °C lower than using water. Results showed an ideal copolymerization behavior; therefore, the Tcp could be tuned by an adequate monomers feed ratio obtaining polymers which may be used in drug delivery and other applications.
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