Well-defined thermoresponsive dendritic polyamide/poly(N-vinylcaprolactam) block copolymers

ABSTRACT The first‐ and second‐generation well‐defined thermoresponsive amphiphilic linear–dendritic diblock copolymers based on hydrophilic linear poly(N‐vinylcaprolactam) and hydrophobic dendritic aromatic polyamide have been synthesized via reversible addition fragmentation chain transfer polymerization of N‐vinylcaprolactam by employing dendritic chain‐transfer agents possessing a single dithiocarbamate moiety at the focal point. These linear–dendritic copolymers exhibit reversible temperature‐dependent phase transition behaviors in aqueous solution as characterized by turbidity measurements using UV–vis spectroscopy. Their lower critical solution temperatures depend on the generation of the dendritic aromatic polyamides and the concentrations of the copolymer solutions. These amphiphilic copolymers are able to form nanospherical micelles in the aqueous solution as revealed by fluorescent spectroscopy, dynamic light scattering, and transmission electron microscope (TEM). The core–shell structure of micelles has been proved by 1H NMR analyses of the micelles in D2O. The micelles loaded with indomethacin as a model drug showed high‐drug loading capacity and thermoresponsive drug release behavior. © 2013 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2013, 51, 3240–3250 Thermoresponsive amphiphilic linear–dendritic block copolymers, composed of hydrophilic poly(N‐vinylcaprolactam) chains and hydrophobic dendritic aromatic polyamide, have been designed and prepared by reversible addition fragmentation chain transfer polymerization. Their lower critical solution temperatures (LCSTs) depend on the generation of the dendrons and the concentrations of the copolymer solutions. They are capable of self‐assembling into nanospherical micelles in water. A sustained drug release is achieved from the copolymer micelles, which is accelerated when the environmental temperature is raised slightly above the LCST.