Research articles

The aggregation states from the interface to the bulk of the adhesive/adherend is a key to unraveling adhesion at the molecular level. We applied X-ray absorption spectroscopy (XAS) in combination with an Ar gas cluster ion beam (Ar GCIB) to poly(methyl methacrylate) (PMMA) films adsorbed onto a SiO_x/Si(111) surface. GCIB-XAS analysis revealed that the orientation of the C=O group in the side chain of PMMA differs between the region from the SiO_x interface to a distance on the order of 1 nanometer and the bulk PMMA region.

The effects of the addition of a hyperbranched polymer (HBP) on the degradability characteristics of linear polyglycolide (PGA) fiber mats. It was revealed that HBP acted as a plasticizer, especially in underwater environments. The weight loss of the PGA fiber mats was accelerated with increasing HBP content. Considering that the structural changes in the PGA crystals depended on the feed amount of HBP, it was claimed that HBP promoted PGA degradation in both the amorphous and crystalline phases.

We designed multiblock amphiphilic cyclophanes that possess twisted aromatic units with axial chirality. Electronic absorption and emission spectroscopy revealed that these cyclophanes are molecularly dispersed in organic solvents, while they form aggregates in aqueous environments. We also found that under aqueous conditions, the chiral aromatic units within homochiral cyclophanes adopt a more planar conformation compared to their diastereomer, demonstrating the possibility of stereoselective recognition. Furthermore, by comparing the corresponding multiblock amphiphiles that are linear and chiral, we found that the macrocyclic structure might be essential for recognition.

Inspired by mussel adhesion, polydopamine ultrathin films were formed at silicone oil/water interfaces even in neutral solutions. The MCF-7 cells successfully adhered to the oil/water interface without aggregation during cell growth. The interfacial wrinkles were induced by changes in the oil volume and the compressive stress, and the MCF-7 cells adhered to the oil/water interface and were arranged along the wrinkles. The polydopamine interfacial films provide new opportunities to investigate the relationships between toughness and patterns for tissue engineering and regenerative medicine.

The grazing incidence diffracted X-ray blinking was proposed to evaluate the molecular motions occurring at polymer surfaces by measuring X-ray diffraction patterns near the total reflection angle over small time periods. When the crystallized polymer poly{2-(perfluorooctyl)ethyl acrylate}(PC₈FA) film was measured, the results of the decay constants, which are indexes of molecular motions, suggested that the PC₈FA surface is mobile compared to the bulk.