Temperature- and pH-Responsive Dense Copolymer Brushes Prepared by ATRP

Abstract

Dual responsive molecular brushes consisting of statistical copolymers of di(ethylene glycol) methyl ether methacrylate (MEO 2 MA) and either methacrylic acid (MAA) or N,N-dimethylaminoethyl methacrylate (DMAEMA) were synthesized by grafting from poly(2-(2-bromoisobutyroyloxy)ethyl methacrylate (PBIEM) macroinitiators using atom transfer radical polymerization (ATRP). Copolymer brushes with controlled composition and molecular weights ranging from M n ) 600 000 to 1 400 000 with polydispersity indexes (M w /M n ) between 1.18 and 1.45 were obtained. The lower critical solution temperature (LCST) of MEO 2 MA-stat-MAA decreased with the increasing molar fraction of MAA in the copolymer in deionized water but increased in buffer solution at pH 7. At pH 9, the hydrophilicity of polymer increased with ionization of carboxylic acid to further raise the LCST. On the other hand, the LCST of MEO 2 MA-stat-DMAEMA copolymers increased with increasing DMAEMA content at pH 4, 7, and 9. A bottle-brush terpolymer prepared from all three comonomers exhibited LCST at pH 4 and 7 but not at pH 9, which can be attributed to the stronger ionization of MAA. The responsive nature of the copolymer is enhanced by the densely graft structure of a brush copolymer.

Thermosensitive PNIPAM-b-HTPB block copolymer micelles: Molecular architectures and camptothecin drug release

“…DLS determination gives the hydrodynamic diameter or the "equivalent sphere diameter" in solution, while TEM images were obtained in absence of solvent [30]. On the whole, the micellar size is less than 200 nm, which is a desired size of polymer micelles to work as drug carriers [32][33][34]. This size sufficiently guarantees that the drug-entrapped micelles not only avoid premature elimination or clearance, but also accumulate in the target lesion tissues, and hence the micelles are expected to be potentially utilized as drug controlled release carriers.…”

Functionalized Biocompatible Poly(N‐vinyl‐2‐caprolactam) With pH‐Dependent Lower Critical Solution Temperature Behaviors

“…In a typical procedure (Scheme 1 ), TBVCL (0.478 g, 2 mmol), VCL (2.5 g, 18 mmol), AIBN (0.049 g, 0.3 mmol) and freshly distilled are not based on NIPAAm, have been reported with dualresponsive properties, such as copolymers of di(ethylene glycol) methyl ether methacrylate (MEO 2 MA) with either methacrylic acid (MAA) or DMAEMA, [ 18 ] homopolymer of poly( N -ethylpyrrolidine methacrylate), [ 19 ] graft copolymers containing PMAA backbone and oligo(2-ethyl-2-oxazoline) (OEtOx) side chains, [ 20 ] and poly(amidoamine) dendronized poly(2-hydroxylethyl) methacrylate. [ 21 ] These dual responsive polymers have been explored in applications including control of micelle structures, [ 13 , 15 , 17 ] advanced drug delivery systems, [ 12a , 12d , 22 ] fabrication of dual functional nanofl uidic devices, [ 12b ] and modifi cation of gold nanoparticles.…”

When dual and multi-responsiveness meet molecular brushes

“…One example is demonstrated by Matyjaszewski et al who reported dually responsive copolymer brush was consisted of poly((2-bromoisobutyryloxy)ethyl methacrylate) (PBIEM) backbone and poly(2-(2-methoxyethoxy)ethyl methacrylate-stat-N,N-dimethylaminoethyl methacrylatestat-methacrylic acid) (P(MEO 2 MA-stat-DMAEMA-stat-MAA)) side chains [60]. In this system, except for the PMEO 2 MA responding to temperature and PMAA which are sensitive to acid, the PDMAEMA is also a stimuli-responsive segment.…”