Nanoporous Gyroid-Structured Epoxy from Block Copolymer Templates for High Protein Adsorbability

Bioinspired Nanonetwork Hydroxyapatite from Block Copolymer Templated Synthesis for Mechanical Metamaterials

Inspired by Mantis shrimp, this work aims to suggest a bottom-up approach for the fabrication of nanonetwork hydroxyapatite (HAp) thin film using self-assembled polystyrene-block-polydimethylsiloxane (PS-b-PDMS) block copolymer (BCP) with a diamond nanostructure as a template for templated sol-gel reaction. By introducing poly(vinylpyrrolidone) (PVP) into precursors of calcium nitrate tetrahydrate and triethyl phosphite, which limits the growth of forming HAp nanoparticles, well-ordered nanonetwork HAp thin film can be fabricated. Based on nanoindentation results, the well-ordered nanonetwork HAp shows high energy dissipation compared to the intrinsic HAp. Moreover, the uniaxial microcompression test for the nanonetwork HAp shows high energy absorption per volume and high compression strength, outperforming many cellular materials due to the topologic effect of the well-ordered network at the nanoscale. This work highlights the potential of exploiting BCP templated synthesis to fabricate ionic solid materials with a well-ordered nanonetwork monolith, giving rise to the brittle-to-ductile transition, and thus appealing mechanical properties with the character of mechanical metamaterials.

Well-Ordered Nanonetwork Metamaterials from Block Copolymer Templated Syntheses

ConspectusThrough the morphological evolution to give highly optimized complex architectures at different length scales, fine-tuned textures for specific functions in living organisms can be achieved in nature such as a bone core with very complicated porous architecture to attain a significant structural efficiency attributed to delicately structured ligaments and density gradients. As inspired by nature, materials with periodic network structures (i.e., well-defined porous textures) in the nanoscale are appealing and promising for innovative properties. Biomimicking from nature, organic and/or inorganic nanonetworks can be synthetically fabricated, giving broadness and effectiveness when tuning the desired properties. Metamaterials are materials whose effective properties do not result from the bulk behavior of the constituent materials but rather mainly from their deliberate structuring. The performances of fabricating metamaterials will depend on the control of size, shape, order, and orientation of the forming textures. One of the appealing textures for the deliberate structuring is network architecture. Network materials possess self-supporting frameworks, open-cell character, high porosity, and large specific surface area, giving specific functions and complexity for diverse applications. As demonstrated by recent studies, exceptional mechanical performances such as negative thermal expansion, negative Poisson's ratio, and twisting under uniaxial forces can be achieved by the effect of the deliberate structuring with nanonetwork textures. In contrast to a top-down approach, a bottom-up approach is cost-effective, and also it can overcome the size limitation to reach nanoscale fabrication. It can be foreseen that network metamaterials with a feature size of tens of nanometers (referred as nanonetwork metamaterials) may provide new comprehension of the structure and property relationships for various materials. The self-assembly of block copolymers (BCPs) is one of the most used methods to build up well-ordered nanostructured phases from a bottom-up approach with precise control of size, shape, and orientation in the thin films for realistic applications. In this account, we summarize recent advancements in the fabrication of nanohybrids and nanoporous materials with well-ordered nanonetwork textures even with controlled helicity by combining block copolymer self-assembly and templated syntheses for mechanical and optical applications with superior properties beyond nature as metamaterials as well as chiral metamaterials with new properties for chiroptic applications such as chiral plasmonics, beam splitter, and negative refraction. The description of the fundamental facets of a nonconventional structure-property relationship with the characters of metamaterials and the state-of-the-art methodologies to fabricate nanonetworks using block copolymer self-assembly will stimulate research activities for the development of nanonetwork metamaterials with exceptional individual and multifunctional properties for futuristic devices.

Block Copolymer Modified Nanonetwork Epoxy Resin for Superior Energy Dissipation

Herein, this work aims to fabricate well-ordered nanonetwork epoxy resin modified with poly(butyl acrylate)-b-poly(methyl methacrylate) (PBA-b-PMMA) block copolymer (BCP) for enhanced energy dissipation using a self-assembled diblock copolymer of polystyrene-b-poly(dimethylsiloxane) (PS-b-PDMS) with gyroid and diamond structures as templates. A systematic study of mechanical properties using nanoindentation of epoxy resin with gyroid- and diamond-structures after modification revealed significant enhancement in energy dissipation, with the values of 0.36 ± 0.02 nJ (gyroid) and 0.43 ± 0.03 nJ (diamond), respectively, when compared to intrinsic epoxy resin (approximately 0.02 ± 0.002 nJ) with brittle characteristics. This enhanced property is attributed to the synergic effect of the deliberate structure with well-ordered nanonetwork texture and the toughening of BCP-based modifiers at the molecular level. In addition to the deliberate structural effect from the nanonetwork texture, the BCP modifier composed of epoxy-philic hard segment and epoxy-phobic soft segment led to dispersed soft-segment domains in the nanonetwork-structured epoxy matrix with superior interfacial strength for the enhancement of applied energy dissipation.

Supramolecular Chirality Transfer toward Chiral Aggregation: Asymmetric Hierarchical Self-Assembly

Self-assembly, as a typical bottom-up strategy for the fabrication of functional materials, has been applied to fabricate chiral materials with subtle chiral nanostructures. The chiral nanostructures exhibit great potential in asymmetric catalysis, chiral sensing, chiral electronics, photonics, and even the realization of several biological functions. According to existing studies, the supramolecular chirality transfer process combined with hierarchical self-assembly plays a vital role in the fabrication of multiscale chiral structures. This progress report focuses on the hierarchical self-assembly of chiral or achiral molecules that aggregate with asymmetric spatial structures such as twisted bands, helices, and superhelices in different environments. Herein, recent studies on the chirality transfer induced self-assembly based on a variety of supramolecular interactions are summarized. In addition, the influence of different environments and the states of systems including solutions, condensed states, gel systems, interfaces on the asymmetric hierarchical self-assembly, and the expression of chirality are explored. Moreover, both the driving forces that facilitate chiral bias and the supramolecular interactions that play an important role in the expression, transfer, and amplification of the chiral sense are correspondingly discussed.

A novel porous polymeric microsphere for the selective adsorption and isolation of conalbumin

Porous polymeric microspheres, poly(styrene-divinyl benzene, PSDVB)-poly(ethylene glycol monoallyl ether, PEGMAE), termed as PSDVB-PEGMAE, are prepared via double emulsion interfacial polymerization strategy. PSDVB-PEGMAE microspheres exhibit a mean diameter of 2.98 μm, and possess heterogeneous porous structure with a pore volume of 0.354 cm³ g^-1 and a pore size of 34.3 nm. PEGMAE moiety is identified on the external surface of the microspheres, while both PSDVB and PEGMAE moieties are found in the interior pores. The PSDVB-PEGMAE microspheres possess favorable selectivity towards the adsorption of conalbumin (ConA) through hydrogen-bonding and hydrophobic interactions, via surface and inter-pore adsorption. At pH 6, an adsorption capacity of 171.9 mg g^-1 is achieved for ConA. The captured ConA may be readily recovered by stripping with a cetane trimethyl ammonium bromide (CTAB) solution (0.1%, m/v). The microspheres are further used for the isolation of ConA from egg white, deriving high purity ConA as demonstrated by SDS-PAGE assay.

Mesochiral phases from the self-assembly of chiral block copolymers

Self-assembly of block copolymers with chiral sense gives mesochiral phases possessing helical sense. With the controlled chirality of the helical cylinder and chiral network, it is appealing to fabricate chiral materials for applications.

Well-defined monolith morphology regulates cell adhesion and its functions

Hydrophilic epoxy resin-based monoliths were employed as cell culture substrates. The monoliths were made of a porous material with a bicontinuous structure that consisted of a porous channel and a resin skeleton. Monolith disks were prepared with a skinless surface through polymerization-induced spinodal decomposition-type phase separation. The pore sizes, which were well controlled by the polymerization temperature, ranged from 70 to 380 nm. The quantity of protein adsorbed per unit area and the early-stage adhesion of HepG2 cells on the monolith substrates were independent of pore size, meaning they were not affected by surface topology. Long-term cell adhesion, as indicated by adherent cell number and shape, as well as liver-specific gene expression were significantly affected by pore size. In terms of cell shape, number, and gene expression, pores of approximately 200 nm were most suitable for HepG2 cell growth. These results highlight the importance of monolith morphology for use as a cell culture substrate. The well-controlled morphology demonstrated in this work indicates monoliths are capable of supporting growth for various types of cells in a range of applications.