Polyacrylamide pseudo crown ethers via hydrogen bond-assisted cyclopolymerization

Abstract

Polyacrylamide pseudo crown ethers with large inchain rings (15-24 membered) were synthesized by hydrogen bond-mediated cyclopolymerization of bisacrylamides comprising poly(ethylene oxide) spacers (PEGnDAAm, ethylene oxide units: n 5 3-6). The monomers undergo the intramolecular hydrogen bonding of the bisacrylamide units in halogenated solvents to dynamically place the two olefins adjacently. As a result, the bisacrylamides homogeneously allowed controlled radical cyclopolymerization without any macroscopic gelation in 1,2dichloroethane, even at relatively high concentration of monomers (200 mM), to directly provide precision cyclopolyacrylamides and the related copolymers with high cyclization efficiency (84-98%). Owing to the in-chain ring pendants, a cyclopolyacrylamide had glass transition temperature higher than a corresponding polyacrylamide with linear pendants. V C 2016 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2016, 54, 3294-3302

Self‐Assembly of Amphiphilic Random Copolyacrylamides into Uniform and Necklace Micelles in Water

“…Discussion was especially focused on the effects of chain structures, composition, chain length, and molecular weight distribution on self‐assembly behavior and aggregate structures in water. The random copolymers designed herein were based on “acrylamide,” in contrast to methacrylate previously reported (e.g., PEGMA/DMA random copolymers) . Because of amide units (‐CONH‐) and no α‐methyl groups, acrylamide‐based random copolymers are more hydrophilic than methacrylate counterparts to potentially show different self‐assembly and self‐folding properties in water.…”

“…Amphiphilic random copolyacrylamides ( P1 – P9 ) with different composition, chain length, and molecular weight distribution were synthesized via iron‐catalyzed living or free radical copolymerization of a PEG‐bearing acrylamide (PEGAAm) and dodecylacrylamide (DAAm) (Scheme b,c). DAAm content was controlled in the range between 20 and 60 mol%.…”

Cation Template‐Assisted RAFT Cyclopolymerization of Hexa(Ethylene Glycol) Di(meth)acrylates to Thermoresponsive Pseudo‐Crown Ether Polymers

“…Recent advances in polymerization systems and design strategies of monomers [ 3–6 ] have opened possibilities to synthesize cyclo(co)polymers with large in‐chain rings and/or well‐defined primary structures (e.g., monomer sequence) via cyclopolymerization. [ 21–31 ] One promising approach is to use template molecules for controlling bond formation to on‐target structures. Crown ethers and their derivatives, often created by such template‐directed synthesis, [ 32,33 ] are useful not only as functional and supramolecular compounds but also as functional nanopores for cyclopolymers.…”

Complex polymer architectures through free-radical polymerization of multivinyl monomers

“…The latest effort in this regard describes the use of intramolecular hydrogen bonding to shorten the intervinyl distance of DVMs, facilitating the cyclopolymerization, as achieved in the oligo(ethylene glycol) bisacrylamide (OEGnDAAm, n = 3-6, Figure 5, 15). 108 The formation of pseudo-crown ether structures by complexation of ether oxygens in ethylene glycol based divinyl monomers to a cation has been used to shorten the end-to-end distance and enhance cyclopolymerization. 109 In a recent study (Box 2b), such cation templated oligo(ethylene glycol) dimethacrylate (OEGnDMA, n = 4, 5, 6, 8) with pseudocyclic conformation was successfully cyclopolymerized by ruthenium mediated RDRP under high dilution (0.025 -0.1 M), yielding soluble polymers with well-defined MW, large pendent poly(ethylene glycol) (PEG) rings (19-to 30membered rings) and low dispersity at high conversion (~90%).…”

“…Contemporary experimental strategies to engineer MVMs for cyclopolymerization. Cyclopolymerization can be achieved by either using small DVMs (A) 87,[91][92][93]95,96,179 or by orienting the vinyl moieties close to one another through the use of a bulky template (Ba), [100][101][102][103][104][105][180][181][182][183] a metal template (Bc), [106][107][108] by exploiting hydrogen bonding (Bb) [110][111][112] or by constraining the reacting monomers in nanochannels (C) 115 . Figure 6.…”