Functional Graft Poly(N‐isopropyl acrylamide)s Using Reversible Addition‐Fragmentation Chain Transfer (RAFT) Polymerisation

Abstract

A series of NIPAM/4-vinyl benzyl chloride copolymers were substituted with 4(5)-imidazole dithioic acid or N-pyrrole dithioic acid to form multi-functional linear dithioate-functional polymers, which can be used as macromolecular transfer agents in a controlled radical polymerisation (RAFT) process. The presence of imidazole dithioate or N-pyrrole dithioate units along the NIPAM copolymer was determined by (1)H NMR, which showed broad CH-imidazole or CH-N-pyrrole resonances. Subsequent reaction of these multi-branch point polymers to produce graft polymers was achieved by reaction with NIPAM in the presence of AIBN. The graft polymers are produced as mixtures containing the desired product and linear polymer. The linear polymer is produced following transfer to the pendant dithioate group. Some of the branched polymers formed from the imidazole dithioate polymers were insoluble in water whilst others were found to be water soluble only in the presence of copper(II) ions. The use of N-pyrrole dithioate groups was found to substantially increase the solubility of the branched polymers in conventional solvents.

Living Radical Polymerization by the RAFT Process - A Second Update

“…NIPAM [229] 68* [230] S S St [230] (Continued) [45] St [45] S S N N 70 [45,231] St [45,231] NIPAM [231,232] S S N ϩ N 71 [233] St [233] N S S 72 [234] St [234] MA [234] St-b-MA [234] 73 [235] S S tBA [235] tBA-b-338 [235] S S 74 [236] St [236] (Continued) [237] St [237] S CO 2 H S…”

“…B See footnote B of Table 3. GMA [398] St [398] tBMA/DEGMA [398] tBMA/DEGMA-b-GMA [398] MMA [88] 240 [283] S S N 241* S S N MA [399] NIPAM [400] 331 [401] NVPI [220] St [73] 332 [221] 336 [221] 338 [221] NIPAM/369 [390] (DMAM/369) [390] (MA/369) [390] St-b-331 [401] 242 S S N 243 [402,403] [229] MMA [402,403] 244 [404,405] 245 [406] S S N N N MA [406] MA [405] St [404] (Continued) 246* [406] S S N 247 [405] S S N BA [406] MA [406] OA [406] St [406] MA [405] N N S S 248 [405] N N S S C 9 H 19…”

Methods of controlled radical polymerization for the synthesis of polymer brushes

“…Only few attempts were made to use it for the synthesis of loosely grafted brushes [64][65][66] and spherical brushes with poly(vinyl acetate) and polyvinylpyrrolidone chains [67,68].…”

Thermogelling of highly branched poly(N‐isopropylacrylamide)

“…Poly(N-isopropylacrylamide) (PNIPAM) is a wellknown water soluble polymer with low critical solution temperature (LCST) around 32 C. Recently, Rimmer et al synthesized a highly branched PNIPAM with imidazole end groups by a RAFT route, and the polymer was used to purify histidin tagged breast cancer susceptibility protein his 6 -BRCA1. [12][13][14] However, the physical-chemical properties of highly branched polymer have been infrequently studied.…”

“…Here, highly branched PNIPAMs were prepared by an living radical controlled copolymerization of NIPAM monomer and a vinyl contained trithiocarbonate, which works as both monomer and RAFT agent (Scheme I), [12][13][14] and the multi-thiols capped PNIPAMs were obtained by aminolysis of the asprepared hyperbranched PNIPAMs, and then the products were oxidized by air in aqueous solution to form nanoparticles. The thermogelling of the nanoparticles were studied.…”