Synthesis of Double‐Hydrophilic BAB Triblock Copolymers via RAFT Polymerisation and their Thermoresponsive Self‐Assembly in Water

Abstract

Triblock copolymers of poly(N‐isopropylacrylamide)‐block‐poly(N,N‐dimethylacrylamide)‐block‐poly(N‐isopropylacrylamide) were synthesised via RAFT polymerisation using a symmetrical bistrithiocarbonate. Keeping the block length of the permanently hydrophilic middle block constant, the length of the poly(N‐isopropylacrylamide) block was varied broadly. The thermoresponsive aggregation of the polymers in water was studied by 1H NMR, turbidimetry, and dynamic light scattering. The complex aggregation behaviour was block length dependent and occurred under kinetic control. Importantly, different information on the hydrophilic‐hydrophobic transition of the poly(N‐isopropylacrylamide) block was obtained using the various analytical methods and could not be directly correlated.magnified image

Self‐assembly and responsiveness of polypeptide‐based block copolymers: How “Smart” behavior and topological complexity yield unique assembly in aqueous media

“…105,106 Assembly Behavior of BAB Linear Triblock Copolymers with a Responsive Polypeptide Inner Block The aqueous self-assembly behavior of linear triblock BAB copolymers has been evaluated widely for synthetic coilcoil-coil type systems. [107][108][109][110][111] These type of systems are reported to aggregate into sunflower micelles, enabled by molecular bending of a flexible middle block, in dilute solution. 108,111 At higher concentrations, these systems often form network structures from the association of corona chains between micelles resulting in hydrogelation.…”

“…[107][108][109][110][111] These type of systems are reported to aggregate into sunflower micelles, enabled by molecular bending of a flexible middle block, in dilute solution. 108,111 At higher concentrations, these systems often form network structures from the association of corona chains between micelles resulting in hydrogelation. 107,109,110,112,113 A few studies have been devoted to self-assembly of coil-rod-coil BAB triblock copolymers containing a functionalized, hydrophilic gold nanorod center FEATURE ARTICLE block and hydrophobic coil outer blocks.…”

Synthesis of Symmetrical Triblock Copolymers of Styrene and N‐isopropylacrylamide Using Bifunctional Bis(trithiocarbonate)s as RAFT Agents

“…Whereas the thiocarbonyl group may serve as inherent UV-label for end group analysis, [40,[44][45][46][47] the use of 1 H NMR spectroscopy requires the incorporation of moieties, which are easy to identify and well-resolved in the spectrum, into the Z or (till now rarely) the R group of the RAFT agent. [48][49][50][51][52][53] Even more, if both R and Z groups are appropriately labeled so that they can be independently quantified, [54,55] the extent of end group functionalization may be estimated by the Z/R ratio in the polymers. [55] This is a precious information, e.g., for the synthesis of high quality macroRAFT agents, which can be hardly obtained by other methods.…”

“…[48][49][50][51][52][53] Even more, if both R and Z groups are appropriately labeled so that they can be independently quantified, [54,55] the extent of end group functionalization may be estimated by the Z/R ratio in the polymers. [55] This is a precious information, e.g., for the synthesis of high quality macroRAFT agents, which can be hardly obtained by other methods. [40,47,55] In this work, we present the synthesis of a series of analogous BAB and ABA triblock copolymers from NIPA and styrene (St), using seven different bifunctional trithiocarbonates as RAFT agents.…”

Living Radical Polymerization by the RAFT Process – A Third Update

“…A [475] BA [311] 349 [311] DMAm [475] DMAm-b-NIPAm [475] [474] St [303,474] A [474] tBA [474] St [474] 194…”