Chlorine-based agents, such as sodium hypochlorite (NaOCl), have been used for over a century as highly reliable disinfectants in food manufacturing and medical settings. Not only does NaOCl meet many of the requirements for an ideal disinfectant, but it also possesses excellent cleaning properties. In NaOCl solutions, an equilibrium is maintained between two forms, undissociated hypochlorous acid (HOCl) and dissociated hypochlorite ion (OCl^–), over the pH range of 4 to 10. While HOCl is a potent microbicidal species, OCl^– is known for its powerful cleaning action. In recent years, therefore, the use of pH-controlled NaOCl solutions has been expanding in order to enhance the disinfecting and cleaning effects of NaOCl solutions. However, frequent use of pH-controlled NaOCl solutions often causes degradation or damage to elastomeric sealing materials, which can result in reduced sealing performance and physical contamination due to the delamination or fragmentation of the sealing materials. To maintain the stability and durability of sealing materials, it is necessary to understand the degradation mechanisms of sealing materials exposed to NaOCl solutions. This article focuses on hypochlorous acid and discusses the mechanisms of action of chlorine-based agents, the degradation mechanisms of elastomers, and potential applications.

N-Substituted maleimides (RMI) contain highly reactive unsaturated double bonds and are used not only for radical polymerization and copolymerization but also for stepwise polymerizations using Diels-Alder addition, ene–thiol reaction and so on. The maleimide structure is also used as a highly reactive functional group introduced into the side chain or terminal group of polymers, and is utilized for designing functional and high-performance materials with well-controlled polymer structure. Radical copolymerization is the most commonly used method for polymer synthesis, and RMI exhibits unique copolymerization reactivity depending on the type of comonomer used in the copolymerization. In this review article, our research on the design of transparent and heat-resistant polymer materials by radical copolymerization of RMI is summarized. The copolymerization reactivity of RMI, synthesis and thermal properties of copolymers containing an amino group as N-substituent, properties of RMI/isobutene alternating copolymers, synthesis of RMI copolymers with excellent transparency and high glass transition temperature, and design of network polymers using RMI copolymers are described.