At room temperature, block polymers with hard polymer chains in a glassy or crystalline state (hard segments) and soft polymer chains in a molten state (soft segments) exhibit elastomeric behavior (rubber elasticity). When heated, the entire material melts and flows; however, it regains its rubber elasticity upon cooling. Therefore, these block polymer materials are called thermoplastic elastomers (TPEs). The demand for TPEs continues to grow because of their excellent processability; nevertheless, there is increasing demand for TPEs with superior mechanical properties. Therefore, we investigated noncovalent-bonded block polymer-based TPEs. This review first presents our studies on the synthesis and mechanical properties of poly(4-vinylpyridine)-b-poly(butyl acrylate-co-acrylamide)-b-poly(4-vinylpyridine) and polystyrene-b-poly(butyl acrylate-co-acrylamide)-b-polystyrene triblock copolymers, which are pioneering TPEs with noncovalent bonding groups incorporated into the soft segments. We then review our development of toughened styrenic TPEs with noncovalent bonding groups incorporated into a polyisoprene block of the commercially available polystyrene-b-polyisoprene-b-polystyrene (SIS). Finally, we introduce the application of noncovalent-bonded SIS as an adhesive additive.

Human follicular fluid (HFF) collected during assisted reproductive technology procedures is a complex fluid exhibiting shear-thinning properties. We have investigated the dependence of shear viscosity of HFF on the developmental state of the oocyte. However, the role of interfacial rheology of proteins in HFF affecting its viscosity characteristics remains unclear. In the present study, we evaluated the effect of interfacial aggregation layers formed by proteins on the rheological properties by measuring the shear viscosity, extensional viscosity, and dynamic/static surface tension of HFF and protein solutions. Albumin and fibrinogen, which are abundant in HFF, were employed as the contained proteins. The shear viscosity of all solutions varied depending on the type of rotational rheometers such as coaxial double cylindrical rotary rheometer and cone-plate rheometer, while the extensional viscosity measured using an extensional rheometer employing the liquid dripping method was not affected by the interfacial rheology of interfacial aggregation layers.