Volume 51 Issue 6, June 2019

Dendrimers, a type of dendritic molecule, have a well-defined structure with a homogeneous molecular weight and precise multiple terminal groups. Although the immobilized dendrimer with closely packed terminals was inactive to various proteins due to huge steric hindrance, the immobilized dendrimer with loosely packed terminals and many signature ligands, such as saccharides, was highly active to specific proteins with multivalent interactions at the surface. Additionally, the loosely packed glycodendrimer controlled the biological functionality of proteins by strictly regulated multivalent interactions.

The reactive groups (–OH or –NH₂) of natural melanin nanoparticles from cuttlefishes react with isocyanate groups in pre-polyurethane (pre-PU) to form cross-links, further strengthening the self-healing of PU based on the reversible acylhydrazone bond. The self-healing efficiency was improved from 91.73% to 99.58% due to the strong interactions between the MNs and PU.

Microcellular and nanocellular silicone rubber foam are prepared by supercritical carbon dioxide in this work. The t_pre and P_s are important factors which affect the open-cell content (OCC). When the t_pre and P_s increases, the OCC sharply improves and could reach to more than 96%. The OCC has a significant effect on the mechanical properties of the nano/micro silicone rubber foam.

We discover a new cavitation phenomenon in amorphous polymers sandwiched between two thick slide glasses from the static melt induced by thermal treatment. By quenching atactic polystyrene samples from the static melt under the glass transition temperature (T_g) and annealing them above T_g, cavities are created to relax the negative pressure. Cavity growth undergoes an Ostwald ripening-like process in cases of large molecular weight while it undergoes a viscous fingering process in cases of small molecular weight.

PVA/MWCNT nanocomposite aerogels were fabricated via the ScCO₂ drying method. The aerogels were fully characterized, and their shape memory behaviors were examined. As the MWCNT content was increased, the electrical conductivity increased abruptly by up to 4 orders of magnitude, implying that an electrical percolation network had formed in the nanocomposite aerogels. The shape memory results illustrated the shape recovery ratio, and the recovery speed of the nanocomposite aerogels increased, due to the addition of the MWCNTs.

Solution-cast gold-like lustrous films of oligo(3-methoxythiophene) were subjected to benzene exposure and benzene addition treatments. Both treatments provided films with a higher luster and more intense yellowness, i.e., an enhancement in a gold tone. Such a gold-tone-enhancing effect was explained by a model in which upon the treatments, the oligomers adopt a planar conformation through π–π interactions between benzene and the thiophene rings, and the resulting sandwich structures facilitate the formation of edge-on lamellar crystallites, the most likely gold-tone developing structure.

Two kind of cyclic tri-β-peptides, cyclo(β-Ala(nap)-β-Ala-β-Ala (C3NAA)), and cyclo(β-Ala(nap)-ED-SA) (C3NES), are synthesized. The orientation of the peptide nanotube bundles changes from horizontal to perpendicular on the guanidium-terminated SAM due to the methanol-vapor annealing process. The C3NAA nanotube bundles positioned horizontally along the gold substrate generate a relatively large surface potential, and the converse piezoelectric response is as high as approximately 9 pm/V.

The chain dynamics in a spin-coated poly(methyl methacrylate) (PMMA) film in solvent annealing was studied by in situ neutron reflectivity. The absorbed solvent molecules homogeneously distributed in the spin-coated film and the PMMA chain even near the substrate showed sufficient mobility in the solvent annealing process, while the chain mobility was strongly restricted at the substrate in thermal annealing. This result indicates that the solvent annealing method enables the equilibration of a spin-coated polymer film from the surface to the substrate interface.

N-succinimidyl monomers such as N-methacryloxysuccinimide (MASI) and N-acryloxysuccinimide (ASI) were utilized as prepolymers to synthesize glycopolymers via postpolymerization modification. Living radical polymerization with RAFT agents succeeded using not only MASI but also ASI. While the polymerization with ATRP initiator did not succeed using ASI, the procedure was successful with MASI. MASI was also applicable for SI-ATRP reactions on substrate surfaces. The introduction rate of NH₂-terminated saccharide onto the prepolymer via amine coupling reaction was affected by the reaction temperature. This preparation procedure via postpolymerization modification is expected to provide a facile method for various functional polymers, such as other saccharide and beneficial ligands.