Block copolymer nanoparticles have been widely used for advanced materials. However, the stabilization is challenging. Herein, we present a method for convenient yet reliable synthesis of stabilized polyion complex (PIC) nanometer-sized spheres and micrometer-sized ultrathin lamellae and vesicles by taking advantage of the wavelength orthogonality of UV-induced disulfide exchange and visible light-initiated polymerization-induced electrostatic self-assembly (PIESA). Disulfide-containing PIC vesicles are synthesized at scale using this PIESA, undergoing a small sphere-to-larger sphere-tolamella-to-vesicle transition. As such, surface-neutralized and surface-charged micrometer-sized vesicles can be achieved. UV irradiation of the vesicles (5.0 mg/mL in water) in ambient air induces very fast exchange reaction of locally confined/enriched disulfide motifs, leading to cross-linking, shape transition, and cystamine salt release in 4 min. As such, cross-linked PIC spheres, lamellae, and vesicles can be achieved, in one pot, from one single vesicle precursor. The wavelength orthogonality is evident from disabled PIESA synthesis under UV light and ineffective postpolymerization functionalization under visible light. The cross-linked PIC spheres and micrometer-sized ultrathin lamellae and vesicles show outstanding shape/size stability and high reversibility in the solution-adaptive electrostatic hierarchical self-assembly and disassembly upon adding ethanol into aqueous dispersion and subsequent dialysis.
The noncovalent locking of nanostructured thermoresponsive polyion complexes can be achieved via polymerization-induced electrostatic self-assembly (PIESA) using an arginine-like cationic monomer.
We herein present sequence-controlled polymerizationinduced self-assembly (PISA) via photoswitchable reversible addition−fragmentation chain transfer (RAFT) copolymerization of oppositely-charged monomers using polyethylene glycol chain transfer agent in water at 25 °C. Thorough block copolymerization leads to a polymerization-induced electrostatic self-assembly named ABC-mode polymerization-induced electrostatic self-assembly (PIESA), by which PEGylated (PEG, polyethylene glycol) polyion complex (PIC) spheres, lamellae, and vesicles are achieved. We demonstrate the inherent spontaneous zwitterionic alternating copolymerization nature, which leads to the charge-dictated alternating or gradient zwitterionic sequence. As such, we developed sequencecontrolled synthesis of nanostructured block-gradient zwitterionic terpolymer PICs via complete zwitterionic copolymerization starting from photoswitched incomplete first polymerization, i.e., AB(BC)-mode PIESA. This sequence-controlled PISA method provides the unprecedented control of the low-dimensional polyelectrolyte complex nanostructure involving not only shape but also size and thickness of micrometer-sized ultrathin PIC vesicles and lamellae, without necessarily changing the whole chemical composition and degree of polymerization.
Scalable
synthesis of multicompartment polyion complex (PIC) systems has been
achieved via visible light-initiated RAFT polymerization of cationic
monomer in the presence of anionic diblock copolymer micelles in water
at 25 °C. This polymerization-induced hierarchical electrostatic
self-assembly (hierarchical PIESA) implements structural hierarchy
via programmable self-assembly to form multicompartment PIC micelles
and their monolayer colloidal nanosheets and nanocages. The anionic
micelles play decisive roles in such a hierarchical PIESA to access
biologically relevant yet otherwise inaccessible multicompartment
PIC systems.
Polymerization-induced self-assembly
(PISA) is a powerful method
for the synthesis of polymeric kinetically frozen core nanoparticles.
However, the PISA synthesis of biologically important polymeric fluidic
materials is unexplored. Herein we present a liquid–liquid
phase separation mode PISA. The proof of concept is established by
means of complex coacervation in visible light-initiated RAFT dispersion
polymerization of anionic monomer in the presence of a protonated
polyethylenimine in water at 25 °C. We demonstrate a stage-by-stage
nano to micron droplet growth mechanism via an increase in growing
chain DP or electrical neutralization. Liquid coacervate droplets
and their glassy nanowires or vesicles can be interconverted upon
changing the ethanol/water solvent. As such, tunable construction
of coacervate droplets and nanowires or vesicles can be achieved using
this smart PISA method.
Electrostatic manipulation of triblock
terpolymer nanofilm compartmentalization
has been achieved via visible light-initiated reversible addition–fragmentation
chain transfer aqueous dispersion polymerization of diacetone acrylamide
monomer using cationic–neutral diblock copolymer macro-chain
transfer agent (macro-CTA) at 25 °C. This photoinitiated polymerization-induced
self-assembly (photo-PISA) evolves into two modes depending on solution
pH. At pH 2.5, this macro-CTA dissolves in water with a fully cationic
block; electrostatic repulsion leads to conventional aqueous photo-PISA
and the formation of monolayer colloidal nanofilms. At pH 7.3, the
cationic block transforms to a hydrophobic ionomer block with 10%
cationic repeat units, and the copolymer chains self-assemble into
weakly cationic micelles, which leads to seeded photo-PISA via self-assembly
into discrete nanoclusters within the hydrophobic lamellar framework
to form multicompartmentalized monolayer nanofilms. The nanoscale
phase-separated 2D-confined nanoclusters and the lamellar structure
can be tuned by the ABC/BAC block sequence, the degree of polymerization
of the growing block, and the copolymer concentration. This electrostatic
manipulation sheds new light on the rational design and preparation
of multicompartmentalized block copolymer 2D nanoobjects.
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