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

Poly(N-vinylcaprolactam), a comprehensive review on a thermoresponsive polymer becoming popular

“…Only a few CRP techniques can properly mediate the radical polymerization of NVCL, including reversible additionfragmentation chain transfer (RAFT) [16][17][18][19][88][89][90][91][92][93][94][95], a combination of ring-opening polymerization (ROP) and RAFT [96,97], atom transfer radical polymerization (ATRP) [98], and Cobalt mediated radical polymerization (CMRP) [20,29,66]. Devasia et al [88] reported the first sequential RAFT polymerization to prepare block copolymers of A c c e p t e d M a n u s c r i p t 25 polymerization.…”

“…al [93]. synthesized first and second-generation well-defined linear-dendritic block copolymers containing PNVCL linear chains and polyamide dendrons via RAFT polymerization of NVCL using dendritic CTA´s possessing a single dithiocarbamate moiety.…”

Functional aqueous assemblies of linear‐dendron hybrids

“…As an alternative thermosensitive block, Bi et al have investigated poly( N ‐vinylcaprolactam) (PNVCL), which was polymerized from the focal point of G1 and G2 polyamide (PA) dendrons via RAFT . The degree of polymerization of PNVCL was 46 and 55 for the G1 and G2 systems, respectively.…”

Synthesis and tunable thermoresponsive solution morphologies of 2,2‐bis‐methylolpropionic acid dendron–azobenzene–poly(N‐isopropyl acrylamide) copolymers

“…Corresponding diblock copolymer analogues were prepared using monodendron chain‐transfer agent to polymerize NIPAM as well as pyrene‐labelled NIPAM . A copolymer of dendritic aromatic polyamide as hydrophobic block and poly( N ‐vinyl caprolactam) as hydrophilic block was also synthesized using RAFT . Although reversible transition between micellar assembly and disassembly with temperature has been reported in linear–dendritic copolymers, there are few reports that describe temperature‐responsive transformation of one well‐defined morphology into another.…”

“…A copolymer of dendritic aromatic polyamide as hydrophobic block and poly( N ‐vinyl caprolactam) as hydrophilic block was also synthesized using RAFT . Although reversible transition between micellar assembly and disassembly with temperature has been reported in linear–dendritic copolymers, there are few reports that describe temperature‐responsive transformation of one well‐defined morphology into another. For example, poly(benzyl ether) dendron‐ block ‐PNIPAM copolymer synthesized using a dendron atom transfer radical polymerization (ATRP) macroinitiator exhibited a change in morphology from micelles to entangled nanotubes above the LCST .…”