To investigate the effect of the network structure on the mechanical properties of a polymer network formed from a certain polymer, we should prepare polymer networks with clearly different network structures made of the same polymer and compare the mechanical properties of these polymer networks. If a living radical polymerization method is applied to the same monomer constituting the polymer network with a nonuniform network structure obtained by conventional free-radical polymerization, it is possible to obtain a polymer network with a uniform network structure in which the molecular weights of the polymer chains bonded to the cross-linking points are uniform and the number of chains bonded to the cross-linking points is constant. In this study, we worked on the synthesis of a polymer network with a uniform network structure by combining two different types of star-shaped polymer synthesis methods using living radical polymerization, i.e., the core-first method and the linking method. In the core-first method, it was possible to synthesize a star-shaped polymer with a narrow molecular weight distribution in a state with a molecular weight corresponding to the charging ratio of the initiator with four initial groups and the monomer. We confirmed that the polymer network obtained by binding the star-shaped polymers by the linking method had a uniform structure, even when swollen with a good solvent or dried, from small-angle X-ray scattering. Depending on the molecular weight of the star-shaped polymer obtained by the core-first method and the amount of the cross-linking agent added for the linking method, the mesh size of the network could be changed while having a uniform network structure. The dried polymer network with uniform network structures exhibited significantly higher values of fracture extensibility and energy than those with nonuniform network structures via conventional free-radical polymerization, when compared at the same monomer and cross-linker concentration.

Cholesteric liquid crystals (CLCs) are becoming increasingly popular due to their unique chiral structural color. Unlike ordinary CLCs materials, CLCs particles exhibit angle‐independence, making them particularly noteworthy. However, currently, there are limited effective methods for controlling the structural color of CLCs particles, other than adjusting the concentration of chiral dopants or introducing stimuli‐responsive groups. Here, a scalable and cost‐effective process for preparing monodisperse CLCs particles via dispersion polymerization is reported. By making CLCs into micrometer‐sized monodisperse spheres, the helical pitch of CLCs can be varied according to its particle size, and the resulting structural color hue due to Bragg reflection can also be changed. Covering the CLCs particles with polydimethylsiloxane results in the formation of a polymer dispersed liquid crystals–like structure, which enhances the structural color appearance and thermal stability of the CLCs particles. Additionally, a simple strategy to produce chiral anti‐counterfeiting QR codes is developed. By combining CLCs particles with commercially available pigments, an anti‐counterfeiting QR code that can only be displayed under a specific circular polarizer is created. This approach and resulting CLCs particles expand the modulation of CLCs structural color and enrich the application of structural color in the field of chiral optical anti‐counterfeiting.

Metrics & MoreArticle Recommendations * sı Supporting Information CONSPECTUS: Soft materials, which are optically transparent and exhibit high mechanical performance, will be key materials in important research areas in our future lives, such as highly advanced medicine, soft robotics, and wearable displays. When soft materials are transparent, objects underneath the soft material can be observed by the naked eye. Additionally, because they allow light to pass through, such materials can be used in optical applications such as lenses and displays. Therefore, transparent materials make it possible to transmit light information. Such transparent soft materials have been widely used in our daily life, but their applications will be directed to higher value-added products in the future.One example of a great transparent and flexible soft material is transparent silicone rubber, but even this material is not without drawbacks. Silicone rubber has the property of not adhering to most materials. This feature can be an advantage, but it can also be a disadvantage in some applications. Moreover, its tensile strength, tear strength, and friction resistance are not always strong. The ability to develop transparent soft materials whose surface and mechanical properties differ from those of silicone rubber will lead to the development of various technologies that will enrich our lives. By use of colloid-sized molecules and materials as building blocks to form soft materials, the properties and functions of the resulting soft materials are expected to reflect those of the building blocks. In addition, if the soft material is formed such that the building blocks have a characteristic order, the physical properties derived from the ordered structure can be manifested in the soft material. If the size of the order is as large as the wavelength of light, it is possible to develop materials that can manipulate light. The authors have been working for many years on soft materials in which building blocks of various colloidal sizes are obtained in an ordered state. As a result, we have reported that we can obtain soft materials that are optically transparent and exhibit a variety of mechanical properties. In this Account, we introduce our various works on optically transparent soft materials consisting of colloidal building blocks that exhibit high mechanical performance. To help you understand our research, a basic description of the optical transparency of the materials and the mechanical properties of the materials is given in the Supporting Information, which you are invited to read if necessary.