Catechol-modified alginates (AlgDAs) with various catechol contents were synthesized and examined as adhesive materials. AlgDA exhibited high adhesive strength with mica and moderate adhesive strength with polymer resins, although this adhesiveness was not observed for sodium alginate. AlgDA with a relatively low catechol content exhibited relatively high adhesive strength, unlike other catechol-modified polymer adhesives. AlgDA residues were successfully removed from the used substrates by a simple water washing process. AlgDA is promising as a biobased adhesive material that contributes to a sustainable society.

Sustainable and 100% biobased plastics, polyamide 11 (PA11), derived from nonedible plants are mixed with polypropylene (PP) and a reactive compatibilizer in a twin-screw extruder. It is found that PP/PA11 bioalloys exhibited surprisingly good impact strength without losing flexural modulus only when the morphology of the PP/PA11 bioalloys was well controlled at nano-meter level, such as “nano-salami” structure. This leads to overcome a past and traditional issues in biobased plastics, resulting in applying for automobile plastic parts. This technology would contribute to realizing “carbon neutrality”.

We fabricated polymer brushes using a novel concept, which involves block copolymer segregation from the polymer region at the water interface. The resulting polymer brush is called a dynamic polymer brush because block copolymer segregation is a dynamic process that occurs at room temperature and is activated through contact with water. Dynamic polymer brushes undergo self-organization in the processes of self-assembly and self-healing (if destroyed). The concept and physical characteristics of dynamic polymer brushes are discussed in this review.

A series of amphiphilic diblock copolymers (PVA_m-b-PVPi_n: m/n = 82/6, 72/26, and 70/74) with different block lengths of hydrophilic poly(vinyl alcohol) (PVA) and hydrophobic poly(vinyl pivalate) (PVPi) blocks were prepared. PVA_m-b-PVPi_n was synthesized from poly(vinyl acetate)-b-PVPi (PVAc_m-b-PVPi_n) diblock copolymer via selectively hydrolysis. In water, PVA_m-b-PVPi_n formed spherical polymer micelles with a PVPi core and a PVA shell. The hydrodynamic radius, light scattering intensity, and aggregation number of PVA_m-b-PVPi_n increased with increasing PVPi block length. In contrast, the critical micelle concentration was reduced because of stronger hydrophobic interactions.

This focus review summarized current adhesives that are capable of macroscopic adhesion in seawater. The design strategies and performance of these adhesives were reviewed based on their bonding methods. Some future research directions and perspectives for under-seawater adhesives were discussed.

The conformational relaxation of ethylene-propylene-diene terpolymer (EPDM) chains at the interface with a model filler of quartz was examined by sum frequency generation (SFG) spectroscopy in conjunction with molecular dynamics (MD) simulations. We found that the glass transition temperature (T_g) of EPDM was higher at the interface than in the bulk. Also, the conformational relaxation beyond the T_g was significant for ethylene units, but not for propylene units. This information might be useful in controlling the local conformation and dynamics of polymer chains at the interface.

Microstructure-free strong all-wooden nanocomposites (AWNC) was directly made from the weak raw wood (RW) of paulownia, in which microscale wood fibers and void structures were dismantled into a fully consolidated structure containing nanofibrils (as the reinforcing phase) and noncrystalline cellulose, lignin, and hemicelluloses (as the matrix phase). This direct conversion was carried out through simultaneous chemomechanical densification/downsizing in three steps, including (1) partial delignification, (2) partial dissolution with IL or oxidation with TEMPO and ammonium persulfate (APS), and (3) hot pressing with cyclic pressurizing-depressurizing conditions.

Various in situ measurement techniques have been applied to investigate changes in the three-dimensional structures and the physical properties of polyimides (PIs) generated at high pressures using a custom-built optical cell (up to 4,000 atm) or a diamond anvil cell (up to 80,000 atm). Moreover, the structural changes in the PI chain repeating units and interchain distances induced by the ultrahigh pressures were observed with WAXD, and they were compared with optical absorption, fluorescent and phosphorescent emission spectra, infrared absorption spectra, and refractive indexes observed under the same conditions.

Two types of polyimide nanofibers (PINFs) were prepared. PINF-I (lengths = 305 ± 152 nm and diameters = 12 ± 2 nm) was prepared via crystallization of PI dissolved in a concentrated sulfuric acid solution. Adding t-butanol to a PINF-I aqueous dispersion and subsequent freeze–drying produced PINF-II (diameters = 105 ± 99 nm) with PINF-I aggregated into a fibrous form. The PI crystalline unit cell parameters were orthorhombic, a = 1.21 nm, b = 0.88 nm, and c = 2.23 nm (molecular chain axis direction).