Confined polymerization: multidimensional regulation, advanced measurements and cutting-edge applications.

Confined polymerization, as an innovative polymerization strategy, achieves precise control over the reaction pathway and microscopic structure of the product by confining the polymerization reaction within the physical space of a micro-nano scale. Compared with traditional large-scale or solution polymerization, confined polymerization is carried out in confined spaces, such as nanochannels, layered intermediate layers, or porous material pores, significantly altering properties such as the polymerization rate, molecular weight distribution, glass transition temperature, and product morphology. This review systematically classifies the limited-domain polymerization strategies in different dimensional spaces, clarifies their mechanism differences, and emphasizes the progress in characterisation techniques, including in situ microscopy, spectroscopy, and computational simulation. Additionally, we discuss confined polymerization in cutting-edge applications, such as water purification, medical diagnosis and treatment, energy storage, catalysis, and composite coatings. By combining fundamental principles with functional innovation, we identify the key challenges, such as real-time mechanism detection and scalable synthesis, and propose future directions, including dynamic limitations, biomimetic design, and AI-driven optimization. The aim of this article is to stimulate the attention of more scholars to the field of confined polymerization, thereby accelerating breakthrough progress in this field and providing innovative material solutions for global challenges such as climate change, disease treatment, and clean energy.