Application of Stable Radicals as Mediators in Living-Radical Polymerization - Stable Radicals: Fundamentals and Applied Aspects of Odd-Electron Compounds - page 424

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. 249

11.6.2 Block copolymers
Block copolymer formation beginning with nitroxide-terminated polystyrene has been extensively
studied, 101,234,235,250 - 258 as have block copolymers prepared by nitroxide-terminated homopolymers
other than polystyrene. 4-OxoTEMPO-terminated n -butyl acrylate homopolymers were used to prepare
poly( n -butyl acrylate- b -styrene) and poly( n -butyl acrylate- b - t -butyl acrylate). 259

In a similar manner

acrylate- b -styrene). 101

TIPNO-terminated poly( n -butyl acrylate) gave poly( n -butyl The synthesis of

poly(2-vinylpyridine- b -acrylonitrile) was reported by Lokaj et al . 260
Amphiphilic diblock copolymers containing segments of monomethoxypoly(ethylene glycol) and
polystyrene (MPEG-b-PS) were synthesised using a MPEG-TEMPO macroinitiator. 261 Block copolymers
containing methacrylates have also been synthesized by preparing a first block of a random copolymer
of MMA with styrene and chain extending this SG1-terminated polymer with either styrene or n -butyl
acrylate. 119 Another unique block copolymer was formed by the polymerization of n -butyl acrylate
in the presence of SG1, which was then chain extended with a mixture of methyl methacrylate and
N , N -dimethyl acrylamide to create a random copolymer as the second block. An n -butyl acrylate
macroinitator containing an alkoxyamine SG1 linkage on both ends was also synthesized and chain
extended with methyl methacrylate and N , N -dimethyl acrylamide to give a triblock copolymer. 262
The RAFT and SFRP processes have been combined to make amphiphilic and thermosensitive graft
copolymers, such as P(St- co -(p-CMS))- g -PNIPAAM. 263 Other amphiphilic block copolymers containing
segments of monomethoxypoly(ethylene glycol) and polystyrene (MPEG-b-PS) using TEMPO have been
reported by Shoaeifar et al . 264 The formation of block copolymers containing protic functionalities has also
been accomplished. An amphiphilic block copolymer was synthesized beginning with the polymerization
of acrylic acid in the presence of a small amount of styrene to form a SG1-terminated polymer that was
then chain extended with styrene. 265 The synthesis of tapered blocks has been reported by Jabber et al . 266
Triblock copolymers of styrene/isoprene/styrene and styrene/butadiene/styrene using TEMPO as the
nitroxide mediator have been prepared with narrow molecular weight distributions (M w /M n 3). 267

Semicrystalline poly(octadecyl acrylate- b -methyl acrylate) and poly(methyl acrylate- b -octadecyl acrylate-
b -methyl acrylate) copolymers have recently been prepared using SG1 as the mediating nitroxide. 268
Nitroxide-mediated polymerization of styrene, n -butyl acrylate, t -butyl acrylate, isoprene, and dimethy-
lacrylamide to form symmetrical ABA triblock copolymers was executed using a TIPNO-terminated
bidirectional alkoxyamine. 269 Triblocks, comprising poly( n -butyl acrylate) as a first or central block and
polystyrene or poly(methyl methacrylate) as a second or outer block, have also been made using SG1
under emulsion conditions to give nanostructured latex particles. 270
As an extension to the block copolymer work the synthesis of comb/brush structures, 271 - 276 star
polymers 277 - 282 and hyperbranched polymers have been reported. 283 Two recent reviews are recom-
mended. One covers click chemistry and includes a section on the use of living-radical polymerizations
processes to make graft copolymers 284 ; the second summarizes the progress in the field of polymer
conjugates 285 and again includes a section on the use of living-radical polymerization processes to obtain
polymer conjugates.

∼ 1 .