Phosphorus‐Containing Gradient (Block) Copolymers via RAFT Polymerization and Postpolymerization Modification

Abstract

Reversible addition-fragmentation chain transfer (RAFT) copolymerization of styrene (St) and 4-(diphenylphosphino)styrene (DPPS) is explored to establish the statistical distribution of the phosphine-functional monomer within the copolymer. RAFT copolymerization of St and DPPS at a variety of feed ratios provides phosphine-functional copolymers of low dispersity at moderate monomer conversion (Ð <1.2 at conv. >60%). In all cases the fraction of DPPS in the resulting polymers is greater than that in the monomer feed. Estimation of copolymerization reactivity ratios indicates DPPS has a strong tendency to homopolymerize whilst St preferentially copolymerizes with DPPS (r DPPS = 4.4; r St = 0.31). The utility of the copolymers as macro-RAFT agents in block copolymer synthesis is demonstrated via chain extension with hydrophilic acrylamide (N,N-dimethylacrylamide (DMAm)) and acrylate a Supporting Information is available online from the Wiley Online Library or from the corresponding author.-2 -(poly(ethylene glycol) methyl ether acrylate (mPEGA); di(ethylene glycol) ethyl ether acrylate (EDEGA)) monomers. Finally access to polymers containing phosphine oxide and phosphonium salt functionalities is shown through post-polymerization modification of the phosphine-containing copolymers.

Asymmetric Copolymers: Synthesis, Properties, and Applications of Gradient and Other Partially Segregated Copolymers

“…Spontaneous gradient copolymers have been obtained via catalyst transfer polycondensation, [35] catalyzed copolymerization of olefins [36] and epoxides, [37] diverse RDRP methods (ATRP, [43][44][45][46][47][48] NMP, [49][50][51][52][53][54][55][56] OMRP, [57] RAFT, [22][23][24][58][59][60][61] ) as well as cationic ring opening polymerization. [28][29][30][31][32][33] Also, the gradient-composition backbone can be used as macroinitiators to synthesize high-molecular-weight brushes.…”

“…Many techniques have been used for the preparation of asymmetric copolymers, including anionic [27] and cationic [28][29][30][31][32][33] polymerizations, C1 polymerization, [34] catalyst transfer polycondensation, [35] catalyzed copolymerization of olefins [36] and epoxides, [37] ring-opening metathesis polymerization (ROMP) [38][39][40][41][42] and various RDRP techniques (e.g., atom transfer radical polymerization (ATRP), [43][44][45][46][47][48] nitroxide-mediated polymerization (NMP), [49][50][51][52][53][54][55][56] organometallic-mediated radical polymerization (OMRP), [57] and reversible addition-fragmentation chain transfer (RAFT) [22][23][24][58][59][60][61] ).…”

“…Similarly, a wide range of monomers have been used, including acrylates and methacrylates, [26,43,45] acrylamides/ methacrylamides, [22,23] styrenics, [24,27,62] olefins, [36,62] vinyl esters, [22,23] and epoxides. [37] Both monomers must be compatible with the chosen polymerization technique and should ideally propagate rapidly and terminate relatively slowly in order to allow long chains to be prepared while maintaining acceptable levels of termination.…”

Effect of Scandium Triflate on the RAFT Copolymerization of Methyl Acrylate and Vinyl Acetate Controlled by an Acid/Base “Switchable” Chain Transfer Agent

“…The ideal approach to obtain control over a copolymerization of MAMs and LAMs would encompass modulation of the RAFT agent activity, through an activation/deactivation process, during the polymerization reaction (see Scheme 2). Indeed this would facilitate both efficient addition of MAMderived propagating radicals to the thiocarbonyl of the activated (macro)-RAFT agent (2 or 4) and promote fragmentation of LAM-derived propagating radicals from the less stabilised, deactivated RAFT intermediate (6). Acid/base equilibria involving Lewis basic "switchable" dithiocarbamate RAFT agents can be exploited in this context.…”

Effect of the Z‐ and Macro‐R‐Group on the Thermal Desulfurization of Polymers Synthesized with Acid/Base “Switchable” Dithiocarbamate RAFT Agents

“…RAFT‐synthesized polymers may also develop odor on storage due to the formation of volatile sulfur compounds (the latter is notably less of an issue with dithiocarbamates). As a response to these concerns, various end group removal techniques have been developed, which include reaction with nucleophiles (e.g., aminolysis, borohydride reduction), radical‐induced reactions (e.g., coupling, reduction, oxidation), and thermolysis . However, there are few studies on dithiocarbamate end group removal and none of these relate to the switchable RAFT agents.…”