Stimuli-Responsive Spherical Brushes Based onD-Galactopyranose and 2-(Dimethylamino)ethyl Methacrylate

Abstract

Stimuli-responsive spherical brushes composed of 6-O-methacryloyl-1,2:3,4-di-O-isopropylidene-D-galactopyranose (MAIGal) and 2-(dimethylamino)ethyl methacrylate (DMAEMA) are prepared via atom transfer radical polymerization (ATRP) using cross-linked polystyrene nanoparticles covered with a thin layer of 2-(2-bromoisobutyryloxy)ethyl methacrylate (BIEM) as ATRP initiator by the "grafting from" approach. The stimuli-responsive behavior of the deprotected spherical PMAGal-b-PDMAEMA block copolymer brushes is investigated by dynamic light scattering and cryogenic transmission electron microscopy. A brush with arms containing 160 MAGal and 170 DMAEMA monomer units shows a significant contraction of the hydrodynamic radius from 20 to 70 °C at pH = 8 with a cloud point at ≈40 °C, whereas no LCST is detected at pH = 6 and 7 due to the protonation of the DMAEMA units. Aggregates occur at low temperatures and pH 8 due to intermolecular interactions between the chains of different brushes, which disappear above LCST, when the PDMAEMA chains fold back to the core of the brushes, exposing the glycopolymer chains to the outside.

Well-defined ABA- and BAB-type block copolymers of PDMAEMA and PCL

“…It is assumed that PDMAEMA prevents crystallisation, at the same time as it gives rise to a different packing of the polymer chains compared with the one that existed in B, yielding a higher T g . From the Fox equation [eqn (2)], the weight fraction of PCL was estimated to be 36%, which is in line with 1 H-NMR estimation since it would be equivalent to a total molecular weight of 22 300 g mol À1 . The thermal properties of A-3, no crystallinity and a T g in the vicinity of 10 C, are characteristic of the PDMAEMA homopolymer.…”

Multifunctional Amphiphilic Nanoparticles Featuring (Bio)Degradable Core and Dual‐Responsive Shell as Biomedical Platforms for Controlled Release

“…When the pH was increased above 10, the NPs precipitated from the solution. This is in agreement with previous studies on PDMAEMA stars and brushes with a CP at ≈40 °C . Finally, it should be mentioned that P(DMAEMA 99 ‐ co ‐AN 1 )‐SG1 brushes can be easily postfunctionalized into strong cationic or zwitterionic polyelectrolytes and the solution properties can be triggered by salt concentration, light, or electrochemical stimulus, providing additional “smartness” and “stealth” properties to the nanocarriers.…”

“…This is in agreement with previous studies on PDMAEMA stars and brushes with a CP at ≈40 °C. [ 41 ] Finally, it should be mentioned that P(DMAEMA 99 -co -AN 1 )-SG1 brushes can be easily postfunctionalized into strong cationic or zwitterionic polyelectrolytes and the solution properties can be triggered by salt concentration, light, or electrochemical stimulus, [ 42 ] providing additional "smartness" and "stealth" properties to the nanocarriers. The "grafting onto" coating strategy leaves a phosphonate-based initiator residue at the chain end, which can serve as a macroinitiator for chain extension through RDRP of various monomers in aqueous solution.…”

Preparation of 2‐(dimethylamino) ethyl methacrylate copolymer micelles for shape memory materials

“…It is well known that poly(2‐(dimethylamino)ethyl methacrylate) (pDMAEMA) is widely used as a biomaterials double hydrophilic copolymer and environmentally sensitive coating due to its unique chemical structure containing–N(CH 3 ) 2 functional groups , which can be further quaternized or betainized . The literature reveals that the functional monomer 2‐(dimethylamino)ethyl methacrylate (DMAEMA) has been widely used to design stimuli‐responsive hydrogels, micelles, brushes, and other functional membranes grafted onto various substrates . In addition to their responsiveness to pH and temperature, DMAEMA‐based copolymers can also respond to external stimuli such as ion strength, selected ions and other factors in solution .…”