Nitroxide‐Mediated Aqueous Dispersion Polymerization: From Water‐Soluble Macroalkoxyamine to Thermosensitive Nanogels

Abstract

Self‐stabilized nanoparticles with a temperature‐responsive poly[(N,N‐diethylacrylamide)‐co‐(N,N′‐methylenebisacrylamide)] microgel core and a covalently attached hairy shell were synthesized via a simple nitroxide‐mediated controlled free‐radical aqueous dispersion polymerization, using a poly(sodium acrylate) alkoxyamine macroinitiator. With this method, high solid content, surfactant‐free particle suspensions were prepared, with diameter ranging from 49 to 118 nm at high temperature, and able to reversibly swell with water at low temperature. The proposed method requires a limited number of reagents in a simple polymerization procedure and thus avoids many drawbacks generally encountered in the synthesis of thermally responsive microgel particles.magnified image

Block copolymer synthesis by controlled/living radical polymerisation in heterogeneous systems

“…157,176,177 Furthermore, there is increasing attention toward crosslinking polymers during amphiphilic block copolymer synthesis to lock-in morphologies and afford nano/microgels and macrohydrogels with responsive properties. [205][206][207]225 …”

“…and a small amount of free nitroxide SG1 (<10 mol%) 225 to lower the rate of DEAA polymerisation and improve control by more rapidly establishing the persistent radical effect. 158 DEAA polymerisation exhibited good control/livingness at different temperatures (112 and 120 °C) and solids contents (20 -39 wt%), 158 and MBA (<3% of DEAA) was added after 1h of reaction to cross-link the PDEAA core during chain extension whilst avoiding macrogelation.…”

Application of Stable Radicals as Mediators in Living‐Radical Polymerization

“…Living-radical dispersion polymerization has also been performed in water using a surfactant free approach for the polymerization of N, N -dimethylacrylamide. 224 This was accomplished using a two-step process wherein a short poly(acrylic acid) oligomer was first synthesized using SG1 as the mediating radical. This oligomer was then used as a polyelectrolyte macroinitiator in the dispersion polymerization of poly(N, N -dimethylacrylamide).…”

“…Conversely, statistical copolymers produced by living-radical polymerization yield copolymers that contain the same composition, since all chains are initiated simultaneously and grow at the same rate. Using nitroxide-mediated polymerization styrene has been copolymerized with acrylates, 225 -229 methacrylates, 225,229,230 other styrene derivatives, 225,231 -237 acrylonitrile, 226,238 -240 vinyl pyridine, 241 -243 isoprene, 239 malimides, 244,245 N, N -dimethylacrylamide, 224 acrylic acid, 246 methacrylic acid, 247 and maleic anhydride. 248 SFRP statistical copolymers have also been created using monomer combinations that do not include styrene, as, for example, N -isopropylacrylamide with N -tert-butylacrylamide.…”

Network formation in nitroxide-mediated radical copolymerization of styrene and divinylbenzene in miniemulsion: Effect of macroinitiator hydrophilicity

“…Crosslinking CLRP in dispersed systems results in the formation of crosslinked polymer particles (nanogels) [17][18][19][20][21], which may find a range of applications, for example in drug delivery [20,21]. We have previously investigated the nitroxide-mediated polymerization (NMP) of styrene (S) and divinylbenzene (DVB) using 2,2,6,6-tetramethylpiperidine-N-oxyl (TEMPO) in aqueous miniemulsion at 125 C, focusing on the development of the polymer network and molecular weight distributions (MWDs) [22][23][24].…”