Solution and Film Self-Assembly Behavior of a Block Copolymer Composed of a Poly(ionic Liquid) and a Stimuli-Responsive Weak Polyelectrolyte

Cu(0)-mediated atom transfer radical polymerization was used to synthesize a poly(ionic liquid), poly[4-vinylbenzyl-3-butylimidazolium bis(trifluoromethylsulfonyl)imide] (PVBBImTf2N), a stimuli-responsive polyelectrolyte, poly[2-(dimethylamino)ethyl methacrylate] (PDMAEMA), and a novel block copolymer formed from these two polymers. The synthesis of the block copolymer, poly[2-(dimethylamino) ethyl methacrylate]-block-[poly(4-vinylbenzyl-3-butylimidazolium bis(trifluoromethylsulfonyl)imide] (PDMAEMA-b-PVBBImTf2N), was examined to evaluate the control of "livingness" polymerization, as indicated by molecular weight, characterizations of degree of polymerization, and 1HNMR spectroscopy. 2D DOSY NMR measurements revealed the successful formation of block copolymer and the connection between the two polymer blocks. PDMAEMA-b-PVBBImTf2N was further characterized for supramolecular interactions in both the bulk and solution states through FTIR and 1H NMR spectroscopies. While the block copolymer demonstrated similar intermolecular behavior to the PIL homopolymer in the bulk state as indicated by FTIR, hydrogen bonding and counterion interactions in solution were observed in polar organic solvent through 1H NMR measurements. The DLS characterization revealed that the PDMAEMA-b-PVBBImTf2N block copolymer forms a network-like aggregated structure due to a combination of hydrogen bonding between the PDMAEMA and PIL group and electrostatic repulsive interactions between PIL blocks. This structure was found to collapse upon the addition of KNO3 while still maintaining hydrogen bonding interactions. AFM-IR analysis demonstrated varied morphologies, with spherical PDMAEMA in PVBBImTf2N matrix morphology exhibited in the region approaching the film center. AFM-IR further revealed signals from silica nano-contaminates, which selectively interacted with the PDMAEMA spheres, demonstrating the potential for the PDMAEMA-b-PVBBImTf2N PIL block copolymer in polymer-inorganic nanoparticle composite applications.

RAFT polymerization-induced self-assembly of poly(ionic liquids) in ethanol

Poly(ionic liquids) (PILs) exhibit better durability, processability, and mechanical stability than ionic liquids. PIL self-assembly in green solvents is a well-established strategy for preparing polyelectrolytes. Reversible addition-fragmentation chain transfer (RAFT) polymerization-induced self-assembly (PISA) has proven to be the most controllable method for synthesizing polyelectrolytes. However, there have been few reports on preparing high-order morphology PILs by RAFT-PISA. A new type of ionic monomer, 1-butyl-3-(4-vinylbenzyl)imidazolium hexafluorophosphate ([BVBIm][PF6]), was prepared from substitution reaction and ion exchange reaction of 1-butylimidazole and 4-vinylbenzyl chloride. Herein, various morphologies, including spheres, worms, and vesicles, were easily obtained via RAFT ethanolic dispersion polymerization using poly(N,N-dimethylacrylamide) (PDMA43) as the macromolecular chain transfer agent and [BVBIm][PF6] as the monomer. Dispersion polymerization kinetic experiments, dynamic light scattering, transmission electron microscopy, and differential scanning calorimetry were used to investigate the PDMA43-b-P([BVBIm][PF6]) x block nanoparticles. This efficient RAFT-PISA method for preparing functionalized PIL nano-objects with controlled morphologies represents significant progress in this field.

RAFT polymerization-induced self-assembly of semifluorinated liquid-crystalline block copolymers

It is a major challenge to prepare commercially viable scale semifluorinated liquid-crystalline block copolymers (SEFL-BCPs) using solution processing techniques. The technology of selectively solvating one block in a suitable solvent to realize self-assembly provides a promising route for the preparation of core-corona block polymer materials with extensive potential applications. However, considerable limitations have been discovered after much practice. BCP assemblies often require a separate synthesis step and are performed at high dilution. Herein, a one-pot approach combining polymerization-induced and crystallization-driven self-assembly (PISA-CDSA) was used to obtain well-defined, precise compositions of SEFL-BCPs. It is first synthesized via reversible addition-fragmentation chain transfer ethanol dispersion polymerization between 1H,1H,2H,2H-heptadecafluorodecyl acrylate and poly(N,N-dimethylacrylamide) at a concentration up to 20% v/v. Various morphologies, including 1D fiber-like micelles, 2D lamellar structures, and fusion structures, were first observed via transmission electron microscopy. This scalable PISA-CDSA strategy is greatly expanding the morphology scope and applicability of the polymer liquid crystal materials science field.

Synthesis of Poly(methacrylic acid)-block-Polystyrene Diblock Copolymers at High Solid Contents via RAFT Emulsion Polymerization

The combination of polymerization-induced self-assembly (PISA) and reversible-addition fragmentation chain transfer (RAFT) emulsion polymerization offers a powerful technique to synthesize diblock copolymers and polymeric nanoparticles in a controlled manner. The RAFT emulsion diblock copolymerization of styrene and methacrylic acid (MAA) by using a trithiocarbonate as surfactant and RAFT agent was investigated. The Z-group of the RAFT agent was modified with a propyl-, butyl- and dodecyl- sidechain, increasing the hydrophobicity of the RAFT agent to offer well-controlled polymerization of poly(methacrylic acid)-block-polystyrene (PMAA-b-PS) diblock copolymers at high solid contents between 30-50 wt% in water. The kinetic data of the PMAA homopolymerization with the three different RAFT agents for various solvents was investigated as well as the RAFT emulsion polymerization of the diblock copolymers in pure water. While the polymerization of PMAA-b-PS with a propyl terminus as a Z-group suffered from slow polymerization rates at solid contents above 30 wt%, the polymerization with a dodecyl sidechain as a Z-group led to full conversion within 2 h, narrow molar mass distributions and all that at a remarkable solid content of up to 50 wt%.

Synthesis of ABA triblock copolymer nanoparticles by polymerization induced self-assembly and their application as an efficient emulsifier

ABA triblock copolymer nanoparticles of PHPMA-b-PS-b-PHPMA were synthesized by PISA and demonstrated to be an efficient emulsifier.

All poly(ionic liquid) block copolymer nanoparticles from antagonistic isomeric macromolecular blocks via aqueous RAFT polymerization-induced self-assembly

All-poly(ionic liquid) block copolymer nanoparticles are prepared by aqueous RAFT PISA using a couple of isomeric ionic liquid monomers leading to macromolecular building blocks with antagonistic solution behavior in water.

Solution self-assembly of fluorinated polymers, an overview

The incorporation of fluorinated moieties into a polymer can confer unique properties and often lead in solution to original morphologies endowed with rare properties.

Polymerization techniques in polymerization-induced self-assembly (PISA)

The development of controlled/“living” polymerization greatly stimulated the prosperity of the fabrication and application of block copolymer nano-objects.

What will happen when thermoresponsive poly(N-isopropylacrylamide) is tethered on poly(ionic liquid)s?

The thermoresponsive ionic liquid diblock copolymer of poly[1-(4-vinylbenzyl)-3-methylimidazolium tetrafluoroborate]-block-poly(N-isopropylacrylamide) (P[VBMI][BF₄]-b-PNIPAM) containing a hydrophilic poly(ionic liquid) block of P[VBMI][BF₄] is prepared by sequential reversible addition-fragmentation chain transfer (RAFT) polymerization. This P[VBMI][BF₄]-b-PNIPAM exhibits an abnormal thermoresponsive phase transition at a temperature above the phase transition temperature (PTT) of the PNIPAM block. For P[VBMI][BF₄]-b-PNIPAM including a short P[VBMI][BF₄] block, its aqueous solution becomes turbid at a temperature above the PTT of the thermoresponsive PNIPAM block, whereas for P[VBMI][BF₄]-b-PNIPAM containing a relatively long P[VBMI][BF₄] block even in the case of a relatively long PNIPAM block, the aqueous solution remains transparent at a temperature far above the PTT of the PNIPAM block, although a soluble-to-insoluble phase transition of the PINIPAM block is confirmed by dynamic light scattering (DLS) analysis and variable temperature ¹H NMR analysis. The reason that P[VBMI][BF₄]-b-PNIPAM exhibits an abnormal thermoresponse is discussed and ascribed to the highly hydrophilic and charged poly(ionic liquid) block of P[VBMI][BF₄] leading to the formation of small-sized micelles at a temperature above the PTT.

Synthesis of block copolymer nano-assemblies via ICAR ATRP and RAFT dispersion polymerization: how ATRP and RAFT lead to differences

Block copolymer nano-assemblies were synthesized via ICAR ATRP dispersion polymerization employing the CuBr₂/tris(2-pyridylmethyl)amine catalyst in an alcoholic solvent at a relatively low temperature of 45 °C.

A dual responsive hyaluronic acid graft poly(ionic liquid) block copolymer micelle for an efficient CD44-targeted antitumor drug delivery

Illustration of the formation and elevated antitumor mechanism of the HA-g-mPEG-polymers nanocarriers.

Self-assembly of fluorous amphiphilic copolymers with ionogels and surface switchable wettability

Fluorous amphiphilic ionic copolymers of 1H,1H,2H-Perfluoro-1-octene and vinyl imidazole self-assembled in different solvents to form ionogels and exhibits tunable substrate switching wettability.

Polymerization-induced self-assembly of liquid crystalline ABC triblock copolymers with long solvophilic chains

Polymerization-induced self-assembly was exploited to investigate the self-assembly behavior of liquid crystalline triblock copolymers with long solvophilic chains.