Bicontinuous Porous Nanomaterials from Block Polymers Radically Cured in the Disordered State for Size-Selective Membrane Applications

Abstract

Solution-cast blends of lamellar-forming poly­(styrene-stat-butadiene)-block-poly­(lactide), P­(S-s-B)-b-PLA, and peroxide were heated above their effective order–disorder transition temperature, T ODT, to chemically arrest the locally segregated and bicontinuous domains of the block polymer in the fluctuating disordered state. Selective hydrolysis of the PLA domains produced porous networks characterized by using a combination of small-angle X-ray scattering, scanning electron microscopy, and nitrogen sorption analysis. The location of T ODT varied with parameters of the curing system, including peroxide identity and loading, leading to observable changes in the product morphology and pore characteristics with curing temperature. Disordered, bicontinuous structures exhibiting narrow pore size distributions were generated in several cases, rendering the materials attractive for size-selective membrane applications. The versatility of the radical curing approach is highlighted via extension of the solution-based casting protocol toward the preparation of selective membranes for ultrafiltration.

Enhancing ionic conductivity in tablet–bottlebrush block copolymer electrolytes with well-aligned nanostructures via solvent vapor annealing

“…The samples used for TEM characterization were exposed to OsO 4 vapor to stain the aromatic groups, making the LC domains the dark regions in the TEM micrographs. 40 The distance between neighbouring stripes is 29.2 nm (Fig. 5b), which is close to the d-spacing value obtained via SAXS.…”

Co-Casting Highly Selective Dual-Layer Membranes with Disordered Block Polymer Selective Layers

“…To demonstrate this feature, each membrane was subjected to a series of feed solutions containing fluorescently labeled dextran standards of varying hydrodynamic radii. Rejection was determined based on the ratio of the maximum absorbance for the permeate solution to the feed solution using UV–vis spectroscopy. , The rejection profiles for the dual-layer membranes and their corresponding bare PSF supports are presented in Figure a for membranes cast from 18, 20, and 22 wt % solutions of PSF in DMF. The experimentally measured rejection values were corrected using the mass transfer coefficient to account for concentration polarization to give true rejection values (see Supporting Information for further discussion) .…”

“…Recently our group has reported that the fluctuating disordered state in block polymers can be kinetically trapped by either cross-linking above the order–disorder transition (ODT) temperature ( T ODT ) or by rapidly cooling from above the T ODT to below the glass transition temperature ( T g ). − Upon the selective removal of one domain, a bicontinuous network of pores within a supporting glassy matrix was obtained. The resulting pores were shown to have a narrow size distribution, while their disordered and bicontinuous nature eliminated the need for domain alignment during UF membrane fabrication …”

Polymer Cubosomes: Infinite Cubic Mazes and Possibilities

“…Porous particles with internal bicontinuous nanoporous networks have become important materials for potential applications such as ultrafiltration, , drug delivery, ,, catalysis, , and nanotemplating. − The direct self-assembly of BCPs can be a versatile tool to create porous nanostructures with highly ordered cubic crystalline networks. Furthermore, polymer cubosomes with high molecular weight glassy PS blocks possess better structural stability and larger lattice parameters than lipid cubosomes.…”