Controlled Polymerization of Functional Monomers and Synthesis of Block Copolymers Using a β-Phosphonylated Nitroxide

Abstract

4-Vinylpyridine (4VP) and N,N-dimethylacrylamide (DMAA) were polymerized in a controlled manner using a β-phosphonylated nitroxide (N-tert-butyl-N-(1-diethylphosphono-2,2-dimethylpropyl) nitroxide, commonly designated as DEPN) as a control agent. Compared to the results that had previously been reported for the nitroxide-mediated radical polymerization (NMRP) with 2,2,6,6-tetramethylpiperidine-1-oxyl (TEMPO), the polymerization of 4VP was much faster and very well controlled up to higher monomer conversions. Unlike 4VP, the controlled radical polymerization of DMAA using different types of nitroxides had so far remained limited to a very low conversion range (typically inferior to 10%). The use of DEPN gave rise to a very significant improvement of the NMRP of DMAA by providing a good reaction control up to high conversion (approximately 60%). For the first time, the ability of DEPN to control the homopolymerization of DMAA even at high conversion allowed the synthesis of poly(DMAA-b-4VP) block copolymers with a hydrophilic poly(DMAA) block which was longer than the poly(4VP) block. This particular feature should fairly improve the hydrosolubility of the derived amphiphilic cationic polymers, which can be obtained by simple quaternization of the former block copolymers, and extend the scope of their applications.

Micellization and gelatinization in aqueous media of pH- and thermo-responsive amphiphilic ABC (PMMA82-b-PDMAEMA150-b-PNIPAM65) triblock copolymer synthesized by consecutive RAFT polymerization

“…8,9 During the past decade, hydrogels which can switch between free-owing liquid and free-standing gel states have attracted much interest. 10 In particular, great attention has been focused on the intelligent ones, which have broadly tunable characteristics, as they can exhibit a sol-gel transition in response to various external stimuli, such as pH, 11 temperature, 12 and ionic strength, 3 magnetic elds, etc.…”

Microwave-assisted nitroxide-mediated polymerization of alkyl acrylates

“…Inspired by the acceleration of 1 the living cationic ring-opening polymerization of several 2-oxazolines [18][19][20] and findings from the ATRP of methyl methacrylate [12] under microwave irradiation, we have now investigated the controlled nitroxide-mediated radical polymerization (NMP) of methyl acrylate and tert-butyl acrylate with the initiator/radical system MAMA or MAMA/SG1 (Scheme 1), under conventional heating as well as under microwave irradiation. Under conventional thermal heating, the nitroxide SG1 (DEPN, N-tertbutyl-N-[1'-diethylphosphono-2',2'-dimethylpropyl] nitroxide) has recently been successfully applied for the controlled radical polymerizations of several monomers, including styrene [16], n-butyl acrylate [21,22], dimethylacrylamide [23,24] and acrylic acid [25]. Due to its solubility in aqueous systems, the initiator/radical system MAMA is additionally suited for applications in emulsion polymerizations [26].…”

Controlled/Living Radical Polymerization in Aqueous Miniemulsion

“…However, as TEMPO was almost exclusively limited to styrenic monomers (only a sterically hindered TEMPO Y. derivative allowed the control of the n-butyl acrylate polymerization) [29], new acyclic nitroxides (see Figure 7.2b and 7.2c) have been designed to enhance the range of controllable monomers. More precisely, N-íerí-butyl-N-[l-diethylphosphono-(2,2-dimethylpropyl)] nitroxide (SGI or DEPN) [30,31] and N-ferf-butyl-IV-[l-phenyl-2-(methylpropyl)]nitroxide (TIPNO) [32,33] are now able to control the polymerization of styrenics [31,33], alkyl aery lates [31,33], acrylic acid [34,35], acrylamides [36,37] and dienes [20,38]. More recently, a particular nitroxide (2,2-diphenyl-3-phenylimino-2,3-dihydroindol-1-yloxyl nitroxide, DPAIO, see Figure 7.2d) has been designed to control methacrylic esters [39], which represents an alternative to the SGl-mediated copolymerization approach of methacrylates with a very small amount of a comonomer such as styrene [40][41][42][43] or acrylonitrile [44].…”