Concurrent Control over Sequence and Dispersity in Multiblock Copolymers

Abstract

<p>Controlling monomer sequence in synthetic macromolecules is a major challenge in polymer science and the order of building blocks has already been demonstrated to determine macromolecular folding, self-assembly and fundamental polymer properties. Dispersity is another key parameter in material design, with both low and high dispersity polymers displaying complementary properties and functions. However, synthetic approaches that can simultaneously control both sequence and dispersity remain experimentally unattainable. Here we report a simple, one pot, and rapid synthesis of sequence-controlled multiblocks with on demand control over dispersity while maintaining high livingness, excellent agreement between theoretical and experimental molecular weights and quantitative yields. Key to our approach is the regulation in chain transfer agent activity during controlled radical polymerization that enables the preparation of multiblocks with gradually ascending (<i>Ɖ</i>=1.16 →1.60), descending (<i>Ɖ</i>=1.66 →1.22), alternating low and high dispersity values (<i>Ɖ</i>=1.17 →1.61 →1.24 →1.70 →1.26) or any combination thereof. The enormous potential of our methodology was further demonstrated through the impressive synthesis of highly ordered pentablock, octablock and decablock copolymers yielding the first generation of multiblocks with concurrent control over both sequence and dispersity.</p>

Modulation of Polymer Brush Properties by Tuning Dispersity

“…For reversible addition fragmentation chain transfer polymerization (RAFT), temporally controlling the addition of monomeric retarders [ 36 ] or radical species generators [ 37 ] provides opportunities to govern dispersity. Unique to RAFT and its use of chain transfer agents (CTAs), Đ can be regulated by controlled addition of CTAs over time, [ 38 ] mixing of CTAs, [ 6c,d ] or using switchable CTAs [ 39 ] that behave differently depending on the nature of the organic solvents.…”

Facile Control of Molecular Weight Distribution via Droplet‐Flow Light‐Driven Reversible‐Deactivation Radical Polymerization†

“…[ 12‐15 ] Matyjaszewski and others designed MWD controlling protocols by altering catalyst concentrations [ 16‐18 ] or post‐synthetic blending [ 19 ] based on atom transfer radical polymerization (ATRP). The Anastasaki group disclosed that the combination of different chain transfer agents (CTAs) [ 20 ] and variation of CTA reactivity [ 21 ] are attractive to tailor MWDs for homopolymers and multiblock copolymers based on reversible addition‐fragmentation chain transfer (RAFT) polymerization. Goto and coworkers developed dispersity control based on the gradually changed chain‐end reactivity in an alkyl iodide‐mediated RDRP.…”

Multiblock copolymer synthesis via aqueous RAFT polymerization-induced self-assembly (PISA)

“…[1][2][3][4] The extensive customisability of multiblock copolymers has led to an ever-growing list of synthesis routes and multiblock compositions. 1,[5][6][7][8][9][10] Reversible deactivation radical polymerization (RDRP) has been shown to be a powerful synthetic route ever since the pioneering work in 2011, 5 which employed Cu(0)-mediated radical polymerization to synthesize high-order multiblock copolymers. Of particular value has been the implementation of reversible addition-fragmentation chain transfer (RAFT) polymerization in synthesis of multiblock copolymers.…”

“…Of particular value has been the implementation of reversible addition-fragmentation chain transfer (RAFT) polymerization in synthesis of multiblock copolymers. 6,[10][11][12][13][14][15][16][17][18][19][20][21][22] RAFT processes are of keen interest due to their good monomer compatibility, robustness to experimental conditions and heterogeneous system viability. [23][24][25][26][27][28] Early works employing RAFT polymerization showed that without any intermediate purification, consecutive polymer blocks with high conversion could be synthesized by careful selection of conditions to maximise chain end fidelity (livingness).…”