Blending pressure-responsive block copolymers (BCPs) with conventional polymers enables energy-efficient, low-temperature processing through phase transitions induced by pressurization. However, the pressure-responsive phase behavior of BCP/homopolymer blends remains poorly understood. Here, the compressible random-phase approximation theory is extended to BCP/homopolymer blends to construct pressure-composition spinodal phase diagrams. The results reveal that macrophase and microphase separation, as well as the associated transition pressures, are governed by key molecular parameters: the chain-length ratio of homopolymers to BCPs, the absolute chain lengths, and the block ratio. This study provides a theoretical framework for pressure-induced phase transitions in BCP/homopolymer blends, with important implications for the rational design of pressure-responsive polymers with tailored low-temperature processability.

We investigate the nonlinear mechanical response of main-chain cholesteric liquid crystal elastomer films with a lying-helix director configuration (LH-CE), in which the helical axis lies within the film plane. The fingerprint (FP) texture intrinsic to the LH configuration exhibits a dichotomous response to uniaxial stretching depending on the angle (theta 0) between the initial stripe orientation and the stretching direction. Stripe domains with |theta 0| << 90 degrees, which constitute the vast majority of the system, rotate toward the stretching axis while largely preserving their spacing, thereby governing the macroscopic mechanical properties. In contrast, for the minority domains with |theta 0| approximate to 90 degrees, the stripe spacing increases with strain under minimal rotation. Stripe realignment within the film plane produces pronounced anisotropy in macroscopic contraction dominated by width contraction and generates a stress plateau. Subsequent stretching induces untwisting of the helical structure, leading to a steep stress upturn accompanied by strongly anisotropic deformation dominated by thickness contraction. These findings reveal deformation-driven structural evolution of FP textures and provide a basis for mechanically controlling their associated mechano-optical responses.

The synthesis of high-strength gels with many entanglements by radical polymerization with high monomer and low cross-linker concentrations has recently been reported by several groups. In order to elucidate the toughening mechanism of such high-strength gels, the fracture behavior of gels synthesized by radical polymerization is studied by a coarse-grained molecular dynamics simulation. The simulation results qualitatively reproduce the reported experimental results; the gels formed with high monomer and low cross-linker concentrations have a small number of elastically effective chains due to cross-linking, but many polymer entanglements, and exhibit high toughness without sacrificing the shear modulus. In the tough gels, the structural changes that suppress the orientation of the polymer chains in the elongation direction and stress concentration are confirmed. Analysis of the relationship between network structure and fracture behavior reveals that the chain length between cross-linking points and the number of entanglements are important for the toughness of the gels.

The pressure-responsive phase behavior of block copolymers, which is crucial for energy-efficient processing of certain polymeric materials, is systematically studied using a compressible self-consistent field theory based on a simple lattice vacancy model. To date, predictions of the phase behavior have been based mainly on qualitative assessments. In this study, we quantitatively show that large differences in the self-interaction energy between blocks lead to disordering with increasing pressure, while small differences lead to ordering. We discuss the molecular mechanisms underlying the phase behavior with a focus on voids, which account for the compressibility. The results from our theory agrees with the effective Flory-Huggins interaction parameter calculated by the compressible random phase approximation theory. Additionally, extending the theory to multicomponent systems, we investigate the effect of gas absorption on phase behavior, focusing on the balance of interaction parameters. Our results predict that gas absorption enhances pressure-induced ordering.

Understanding the structure-property relationships of semiflexible polymer networks is essential for their rational design and application across diverse fields. While classical static structural characterizations have been widely used, dynamic investigations also provide a powerful approach to analyzing these networks across multiple hierarchical levels in both time and length scales. This study presents a comprehensive methodology to dynamically determine key structural parameters in semiflexible polymer networks, characterizing time, length, volume, and molecular weight of unit segments at their respective hierarchical levels, such as Kuhn monomers, correlation blobs, and network strands. A wormlike micellar solution of sodium dodecyl sulfate and aluminum nitrate was used as a model system representing semiflexible polymers with a large Kuhn length. By combining dynamic experimental techniques, including dynamic light scattering, macrorheology, and microrheology, crucial structural information was obtained. Integrating information derived from the characteristic parameters successfully revealed the hierarchical network structure of the wormlike micelles, with results validated against static light scattering measurements. Notably, this study effectively utilizes the complex viscoelastic modulus obtained through microrheology, which has received limited attention in the literature. This approach holds potential applicability to a wide range of semiflexible polymer networks.

The dynamics of pressure-induced order-disorder transitions in diblock copolymer systems and their effect on the flow properties are investigated. A dynamically extended compressible self-consistent field theory allows us to study nonequilibrium copolymer systems under high pressure. The theory reveals that the differential reduction of free volume across different polymer segments drives the order-disorder transition upon pressure. The pressure-induced transitions lower the energy required for deformations, supporting experimental observations on the low-temperature processability of diblock copolymer materials as a sustainable solution. These findings advance the fundamental understanding of nonequilibrium phase behavior in block copolymers and provide valuable insights for designing polymeric materials with tailored low-temperature processability, based on a clear physical picture of pressure-induced phase transitions.

The effects of polymerization mechanism and polymerization composition on the structure and mechanical properties of gels synthesized by radical copolymerization of monomers and cross-linkers are investigated using a coarse-grained molecular dynamics simulation. The effects of changing the polymerization mechanism from conventional free radical polymerization (FRP) to reversible deactivation radical polymerization (RDRP) depend on the polymerization composition. Due to the change in the number of loop structures depending on the concentrations and reaction rates, the cross-linking efficiency of the RDRP gel is higher at intermediate monomer concentrations than that of the FRP gel, but is lower at low monomer and low cross-linker concentrations and at high monomer concentrations. The influence of the polymerization mechanism on entanglement is almost independent of the polymerization composition, and the number of entanglements is lower in the RDRP gels than in the FRP gels. The stiffness and stretchability of the RDRP gels are lower than those of the FRP gels over a wide range of composition, but at high monomer concentrations, the RDRP gels, which have lower cross-linking efficiency, exhibit higher stretchability than the FRP gels.

Advancing sustainable plastics is crucial to achieving a circular plastic economy. Baroplastics, block copolymers exhibiting order-disorder transitions under pressure, allow polymer processing at ambient temperatures, reducing energy use and avoiding thermal degradation. Their application, however, has been limited by structural constraints. This study introduces poly(ε-caproclactone-random-5-ethyleneketal ε-caprolactone)-block-poly(l-lactide) (PmCL-b-PLLA) as a "baroplasticizer" for nonbaroplastic PLLA. Blending with the block polymers lowered PLLA's flow temperature by up to 100 °C (160 to 60 °C at 50 MPa) while preserving molecular weight after repeated pressure cycles, ensuring recyclability. The improved formability would arise from a pressure-induced ordered (solid)-to-disordered (melt/solid) phase transition. This work eliminates structural constraints in baroplastics, enabling broader low-temperature processing applications and advancing sustainable polymer technologies.

A theory based on a simple lattice vacancy model provides quantitative physical insights into pressure-induced order–disorder transitions of block copolymers.

Water-in-diesel (W/D) emulsion is a promising alternative fuel candidate, as it can simultaneously reduce nitrogen oxides (NOx) and particulate matter (PM) while improving engine performance. Wide scale adoption of this fuel is difficult due to high production and storage costs. Hence, Real-Time Non-Surfactant Emulsion Fuel Supply System (RTES) is a proposed technology to solve these issues by mixing diesel and water in-line directly to the engine. This study presents an updated RTES prototype which incorporated a modular design, with a feedback system to control water injection rate. In this paper, RTES was installed to a common rail injection diesel-powered vehicle and the biodiesel-diesel W/D produced by RTES was analyzed to determine the effect of common rail pressure toward water droplet size and distribution. The vehicle was then tested under the New European Driving Cycle (NEDC) to evaluate vehicle emissions, which will serve as the basis for evaluating the emissions profile of W/D produced by RTES under urban and extra-urban driving conditions. It was found that when subjected to high common rail pressures, W/D droplets produced by RTES reduced by 21.1

Simulations reveal that gels synthesized by controlled radical copolymerization are more uniform than gels synthesized by conventional free radical copolymerization due to the cooperative effects of the properties of controlled radical polymerization.

Dynamic rheological responses of polymer solutions exhibit a range of dynamic modes reflecting the hierarchical structures with different characteristic lengths such as the Kuhn length and mesh size. The polymer contribution to the viscoelastic modulus at each dynamic mode is proportional to the number density of unit segments at the corresponding hierarchical level, allowing for the determination of their molecular weight. This paper evaluates the molecular weight of a Kuhn monomer from the boundary between the Zimm and bending modes, using a worm like micellar solution of cetylpyridinium chloride/sodium salicylate as a model system. Employing high-frequency diffusing-wave spectroscopy microrheology, we determined the molecular weight, which agrees well with that measured by static light scattering. We showed that the radius of the Kuhn monomer was also accurately estimated from the characteristic volume related with the molecular weight. The proposed method holds potential for application across various dynamic modes and polymer solutions.

The ocean constitutes approximately 70% of Earth's surface. Its average depth is 3688 m, of which depths beyond 200 m are classified as the deep sea. The deep sea is distinct from the surface of the ocean in terms of pressure, temperature, and sunlight. The unique physicochemical processes under the extreme environment of the deep sea and the specialized biochemical mechanisms developed by organisms to survive in the deep sea can serve as a vast source of inspiration for scientific and technological advancements. In this Perspective, we discuss three examples of deep-sea-inspired chemistry: (1) soft materials that respond to high pressures such as those observed in the deep sea; (2) molecular self-assembly inspired by the chemistry of hot and compressed water in deep-sea hydrothermal vents; and (3) nanobiotechnology and biomimetics inspired by survival strategies of deep-sea organisms. Finally, we provide an outlook on deep-sea-inspired chemistry. This Perspective aims to promote the sustainable utilization of the ocean based on knowledge, as opposed to the conventional utilization of the ocean solely based on resources. We hope that this Perspective will encourage chemists to harness their inspiration gleaned from the deep sea.

The effects of polymerization concentrations and elementary reaction rates on the network structure and mechanical properties of gels synthesized by free radical copolymerization of monomers and cross-linkers are studied by a coarse-grained molecular dynamics simulation. The shear modulus, the number of elastically effective chains, and the number of trapped entanglements are calculated with varying the concentrations. The results reveal that the experimentally reported high cross-linking efficiency of the gels formed at high monomer concentrations and low cross-linker concentrations is due to the large number of trapped entanglements. The molecular mechanisms of changes in the network structure due to changes in the concentrations are elucidated by analyzing the detailed structure of network strands connecting adjacent cross-linking points. The results with systematically varying the elementary reaction rates indicate that the decrease in the propagation rate suppresses the formation of cyclic structures and reduces the influence of the trapped entanglements, i.e., improves the structural uniformity of the gels.