Synthesis of Comblike Poly(butyl methacrylate) Using Reversible Addition−Fragmentation Chain Transfer and an Activated Ester

Abstract

Comblike polymers of poly(n-butyl methacrylate) were prepared using an activated estertype comonomer (N-acryloxysuccinimide, NAS) to generate branch points. The conventional solution freeradical copolymerization kinetics of n-butyl methacrylate (BMA) and NAS were first investigated by following individual monomer consumption rates by 1 H NMR spectrometry and reactivity ratios of BMA and NAS determined using the terminal model. The reactivity ratios so obtained are both close to 0.2; the joint confidence interval is also determined. Reversible addition-fragmentation chain transfer (RAFT) was then used to grow polymers with controlled backbone and branch chain length. Because both reactivity ratios have similar values, this implies that the copolymer will have a random distribution of NAS and hence of branch points. RAFT-mediated polymerization was first used to synthesize linear poly(BMAco-NAS) chains. Primary hydroxy-functionalized RAFT agents were then immobilized on this linear poly-(BMA-co-NAS) through nucleophilic substitution on the activated ester units of the NAS. From these immobilized RAFT agents, branches were grown upon addition of a further aliquot of monomer (BMA) and initiator (AIBN). The amount of NAS in the starting BMA/NAS composition was varied without adversely affecting the uniformity of the NAS distribution along the resulting linear poly(BMA-co-NAS) backbone. This results in branched polymers whose molecular weight, branching density, and degree of polymerization of branches are all relatively narrow and controlled.

Synthesis of Functional Polymers by Post‐Polymerization Modification

“…[11] In the absence of amino groups, conversion of active esters with hydroxy groups is possible, though elevated temperatures and activating agents such as N,N-dimethylaminopyridine may be required. [13] Polymers bearing NHS ester side chains can suffer from side reactions such as ring opening of the succinimide group and formation of N-substituted glutarimides by ring-closing attack of amides on neighboring active esters. [14] Suppression of these side reactions may be achieved by carrying out the post-polymerization reaction in DMSO at 75 8C for 24 h in the presence of five equivalents primary amine nucleophile.…”

“…[11] Smith et al observed that the extent of grafting of an RGD peptide onto polyNAS decreased with increasing pH value and temperature owing to promotion of hydrolysis. [11] Cline and Hanna have noted that the reactivity of various amines towards aminolysis of p-nitrobenzoyl-Nhydroxysuccinimide in anhydrous dioxane correlated strongly with the basicity of the amino group, though steric hindrance within the investigated set of amines caused certain deviations [11,16] diNAS [8] NAS [18] NMAS [9,15,19] NAS [20] NSVB [20] NAS [4,13] NMAS [21,22] NSVB [23] NNHS [24] PFA [6] PFMA [6] PFVB [25] PFMA [26] NPF [7] NPA [27] NPMA [28] NPA [29] NPMA [30] MAPTT [10] 3 MA [17] MA [31] MA [32] MVI [17,33] VI [33] TMI [34] VDM [35,36] VDM [37] VDM [38] VPDMO [38] IDMO [38] GMA [39] GMA [40] 4-ES [41] GMA [42] GA [43] GMA …”

Experimental Requirements for an Efficient Control of Free‐Radical Polymerizations via the Reversible Addition‐Fragmentation Chain Transfer (RAFT) Process

“…b) Polymerization in dispersed media. [67,122,336] Sty [67,69,122,336,337] MA [67,122,336,337] BuSSty [338,339] AA [340,341] MA b) [341] BA [338] a) [340] b) [341] DMAm [122] C 12 H 25 S-MMA [339] Sty [343] AA [341] BMA a) [342] MA [344] BA [123,345] b) [341] NAS a) [342] NIPAm [346] DMAm [343] …”

“…MMA [117,361] BMA [342] Sty [9] [67,69,336,337,349,[361][362][363][364][365] AA [248,323,[366][367][368][369][370] 4VP [364] MA [336,337,[361][362][363] BA [323,362] …”

Molecular Watchmaking: ab initio Emulsion Polymerization by RAFT‐controlled Self‐assembly

“…Indeed, RAFT can be described as a molecular toolbox with which any desired polymer architecture can be created: in principle, one can place any monomer unit (and sequence of monomer units) anywhere on the chain, and even control branching structure. [24] Significant commercialization of the RAFT process must be through emulsion polymerization, to capitalize on advantages such as low viscosity at high conversion, readily controlled addition of any ingredient, absence of solvents, and direct use of the latex in surface coatings.…”