A systematic study of a polymer-assisted carboxylate-based MOF synthesis: multiple roles of core cross-linked PMAA-b-PMMA nanoparticles

Colloidaly stable carboxylate-based metal organic frameworks (MOFs), grown from acid decorated nanoparticles synthesized via PISA.

Nonequilibrium Processes in Polymer Membrane Formation: Theory and Experiment

Porous polymer and copolymer membranes are useful for ultrafiltration of functional macromolecules, colloids, and water purification. In particular, block copolymer membranes offer a bottom-up approach to form isoporous membranes. To optimize permeability, selectivity, longevity, and cost, and to rationally design fabrication processes, direct insights into the spatiotemporal structure evolution are necessary. Because of a multitude of nonequilibrium processes in polymer membrane formation, theoretical predictions via continuum models and particle simulations remain a challenge. We compiled experimental observations and theoretical approaches for homo- and block copolymer membranes prepared by nonsolvent-induced phase separation and highlight the interplay of multiple nonequilibrium processes─evaporation, solvent-nonsolvent exchange, diffusion, hydrodynamic flow, viscoelasticity, macro- and microphase separation, and dynamic arrest─that dictates the complex structure of the membrane on different scales.

Nano-Fibrous Networks from Co-Assembly of Amphiphilic Peptide and Polyelectrolyte

Organize the matter on an increasingly small scale is sought in order to increase the performance of materials. In the case of porous materials, such as filtration membranes, a compromise must be found between the selectivity provided by this nanostructuring and a permeability in particular linked to the existing pore volume. In this work, we propose an innovative waterborne approach consisting in co-assembling peptide amphiphiles (PA) which will provide nanostructuring and polyelectrolytes which will provide them with sufficient mechanical properties to sustain water pressure. C₁₆-V₃A₃K₃G-NH₂ PA nanocylinders were synthesized and co-assembled with poly(sodium 4-styrenesulfonate) (PSSNa) into porous nano-fibrous network via electrostatic interactions. The ratio between C₁₆-V₃A₃K₃G-NH₂ and PSSNa was studied to optimize the material structure. Since spontaneous gelation between the two precursors does not allow the material to be shaped, various production methods have been studied, in particular via tape casting and spray-coating. Whereas self-supported membranes were mechanically weak, co-assemblies supported onto commercial ultrafiltration membranes could sustain water pressure up to 3 bars while a moderate permeability was measured confirming the existence of a percolated network. The produced membrane material falls into the ultrafiltration range with a pore radius of about 7.6 nm.

Block Copolymer-Based Magnetic Mixed Matrix Membranes-Effect of Magnetic Field on Protein Permeation and Membrane Fouling

In this study, we report the impact of the magnetic field on protein permeability through magnetic-responsive, block copolymer, nanocomposite membranes with hydrophilic and hydrophobic characters. The hydrophilic nanocomposite membranes were composed of spherical polymeric nanoparticles (NPs) synthesized through polymerization-induced self-assembly (PISA) with iron oxide NPs coated with quaternized poly(2-dimethylamino)ethyl methacrylate. The hydrophobic nanocomposite membranes were prepared via nonsolvent-induced phase separation (NIPS) containing poly (methacrylic acid) and meso-2,3-dimercaptosuccinic acid-coated superparamagnetic nanoparticles (SPNPs). The permeation experiments were carried out using bovine serum albumin (BSA) as the model solute, in the absence of the magnetic field and under permanent and cyclic magnetic field conditions OFF/ON (strategy 1) and ON/OFF (strategy 2). It was observed that the magnetic field led to a lower reduction in the permeate fluxes of magnetic-responsive membranes during BSA permeation, regardless of the magnetic field strategy used, than that obtained in the absence of the magnetic field. Nevertheless, a comparative analysis of the effect caused by the two cyclic magnetic field strategies showed that strategy 2 allowed for a lower reduction of the original permeate fluxes during BSA permeation and higher protein sieving coefficients. Overall, these novel magneto-responsive block copolymer nanocomposite membranes proved to be competent in mitigating biofouling phenomena in bioseparation processes.

Synthesis of High χ-Low N Diblock Copolymers by Polymerization-Induced Self-Assembly

Polymerization-induced self-assembly (PISA) enables the scalable synthesis of functional block copolymer nanoparticles with various morphologies. Herein we exploit this versatile technique to produce so-called "high χ-low N" diblock copolymers that undergo nanoscale phase separation in the solid state to produce sub-10 nm surface features. By varying the degree of polymerization of the stabilizer and core-forming blocks, PISA provides rapid access to a wide range of diblock copolymers, and enables fundamental thermodynamic parameters to be determined. In addition, the pre-organization of copolymer chains within sterically-stabilized nanoparticles that occurs during PISA leads to enhanced phase separation relative to that achieved using solution-cast molecularly-dissolved copolymer chains.

A Single Enzyme Mediates the "Quasi-Living" Formation of Multiblock Copolymers with a Broad Biomedical Potential

This study describes a unique "quasi-living" block copolymerization method based on an initiation by a single enzyme. We use this term to describe a process where a preformed polymer chain can be reactivated to continue propagating with a second or third comonomer without addition of new catalyst. The presented strategy involves a laccase (oxidoreductase) mediated initial polymerization of 4-hydroxyphenylacetic acid to a homopolymer containing phenolic terminal units, which in turn can be easily reactivated by the same enzyme in the same reaction vessel to continue propagation with a second monomer (tyramine). Increased copolymer yield (up to 26.0%) and polymer molecular mass (up to M_w = 116 000 Da) are achieved through the addition of previously developed micellar and hydrogel enzyme complexing agents. The produced poly(tyramine)-b-poly(4-hydroxyphenylacetic acid)-b-poly(tyramine) is water-soluble and able to self-assemble in aqueous solution. Both tyramine blocks were successfully modified with ibuprofen moieties (up to 24.6% w/w load) as an example for potential polymer drug conjugation. The copolymerization could be further extended with addition of a third (fluorescent) comonomer in the same reaction vessel to yield a fluorescent pentablock copolymer. The successful modifications and advantageous solution behavior of the produced copolymers demonstrate their viability as versatile drug delivery and/or bioimaging agents, as confirmed by cytotoxicity and cellular uptake studies.

Antimicrobial polylysine decorated nano-structures prepared through polymerization induced self-assembly (PISA)

Polylysine decorated diblock copolymer nano-objects are prepared by polymerization-induced self-assemblyviaRAFT dispersion polymerization of 2-hydroxypropyl methacrylate. Antimicrobial properties of the resulting nano-objects evaluated using a gram positive bacteria.

Synthesis of transition-metal-free and sulfur-free nanoparticles and nanocapsules via reversible complexation mediated polymerization (RCMP) and polymerization induced self-assembly (PISA)

Transition-metal-free and sulfur-free synthesis of spheres, worms, and vesicles via the combination of organocatalyzed living radical polymerization and PISA.

Nano-porous structuresviaself-assembly of amphiphilic triblock copolymers: influence of solvent and molecular weight

Self-assembly of ABA triblock copolymer micelles into porous materials which are subsequently used as filtration membranes.

In situ synthesis of the Ag/poly(4-vinylpyridine)-block-polystyrene composite nanoparticles by dispersion RAFT polymerization

A new method for the synthesis of metal/block-copolymer nanocomposites of poly(4-vinylpyridine)-b-polystyrene (P4VP-b-PS) and Ag nanoparticles by dispersion RAFT polymerization is proposed.

Nano-structured magneto-responsive membranes from block copolymers and iron oxide nanoparticles

Preparation of porous membranes from PMAA-b-PMMA copolymers and magnetic iron oxide nanoparticles and their performance under magnetic fields.

Self-assembly of PS-PNaSS-PS triblock copolymers from solution to the solid state

Morphological development of block copolymer assemblies from solution to the solid state is explored to yield nanostructured materials.