Stimuli-responsive polymer materials can adapt to their environment, regulate ion and molecule transport, change wettability and adhesion, and convert chemical and biochemical signals into optical, electrical, thermal, and mechanical signals. These materials are increasingly used in drug delivery, diagnostics, tissue engineering, and smart optical systems, as well as biosensors, microelectromechanical systems, coatings, and textiles. The review discusses recent advances and challenges in the development of stimuli-responsive polymeric materials self-assembled from nanostructured building blocks. It also provides a critical overview of emerging developments. To sustain life and maintain biological function, nature requires selectively tailored molecular assemblies and interfaces that provide specific chemical functions and structures, which change in their environment. Synthetic polymer systems with similar attributes are often prepared for a wide range of applications, such as responsive biointerfaces, controlled drug delivery, coatings that interact with and respond to their environment, composite materials that actuate and mimic muscle action, and thin films and particles that sense small concentrations of analytes. This article focuses on stimuli-responsive macromolecular nanostructures that can undergo conformational and chemical changes upon receiving an external signal. These changes are accompanied by variations in the physical properties of the polymer. The signal can come from changes in the materials' environment, such as temperature, chemical composition, or applied mechanical force, or be triggered externally by light or exposure to an electrical and magnetic field. The review analyzes recent developments (within the past five years) on the route to applications using stimuli-responsive nanostructured polymer materials and systems in thin films and nanoparticles. The systems covered are summarized in Figure 1. The review discusses two-dimensional (2D) (films) and three-dimensional (3D) (particulates and their assemblies) stimuli-responsive systems from different architectures and fundamental approaches in the area of responsive materials. It then looks at how these fundamental approaches to inducing stimuli-responsiveness in each type of system can be used for applications. Finally, challenges in theory and modeling of these complex systems and future prospects are examined. Reconstructable surfaces can change their wettability, permeability, adhesive, adsorptive, mechanical, and optical properties. Emerging applications include materials with rapidly switchable adhesion to interacting materials (from sticky to non-sticky surfaces) and wetting (from wettable to non-wettable), with switchable appearance and transparency, and coatings capable of rapid release of chemicals, as well as self-healing coatings. Principal architectures and mechanisms include polymer surfaces formed spontaneously in bulk polymer materials, grafted polymer thin films (polymer brushes), thin films of polymer networks, and self-assembled multilayered thin films. The dynamics, amplitude of changes, reversibility, and intensity of the external signal that could trigger the changes are considered when comparing different architectures. Surface reconstruction of bulk polymers often results in long response times (minutes to tens of hours), during which various polymer constituents either migrate to the surface fromStimuli-responsive polymer materials can adapt to their environment, regulate ion and molecule transport, change wettability and adhesion, and convert chemical and biochemical signals into optical, electrical, thermal, and mechanical signals. These materials are increasingly used in drug delivery, diagnostics, tissue engineering, and smart optical systems, as well as biosensors, microelectromechanical systems, coatings, and textiles. The review discusses recent advances and challenges in the development of stimuli-responsive polymeric materials self-assembled from nanostructured building blocks. It also provides a critical overview of emerging developments. To sustain life and maintain biological function, nature requires selectively tailored molecular assemblies and interfaces that provide specific chemical functions and structures, which change in their environment. Synthetic polymer systems with similar attributes are often prepared for a wide range of applications, such as responsive biointerfaces, controlled drug delivery, coatings that interact with and respond to their environment, composite materials that actuate and mimic muscle action, and thin films and particles that sense small concentrations of analytes. This article focuses on stimuli-responsive macromolecular nanostructures that can undergo conformational and chemical changes upon receiving an external signal. These changes are accompanied by variations in the physical properties of the polymer. The signal can come from changes in the materials' environment, such as temperature, chemical composition, or applied mechanical force, or be triggered externally by light or exposure to an electrical and magnetic field. The review analyzes recent developments (within the past five years) on the route to applications using stimuli-responsive nanostructured polymer materials and systems in thin films and nanoparticles. The systems covered are summarized in Figure 1. The review discusses two-dimensional (2D) (films) and three-dimensional (3D) (particulates and their assemblies) stimuli-responsive systems from different architectures and fundamental approaches in the area of responsive materials. It then looks at how these fundamental approaches to inducing stimuli-responsiveness in each type of system can be used for applications. Finally, challenges in theory and modeling of these complex systems and future prospects are examined. Reconstructable surfaces can change their wettability, permeability, adhesive, adsorptive, mechanical, and optical properties. Emerging applications include materials with rapidly switchable adhesion to interacting materials (from sticky to non-sticky surfaces) and wetting (from wettable to non-wettable), with switchable appearance and transparency, and coatings capable of rapid release of chemicals, as well as self-healing coatings. Principal architectures and mechanisms include polymer surfaces formed spontaneously in bulk polymer materials, grafted polymer thin films (polymer brushes), thin films of polymer networks, and self-assembled multilayered thin films. The dynamics, amplitude of changes, reversibility, and intensity of the external signal that could trigger the changes are considered when comparing different architectures. Surface reconstruction of bulk polymers often results in long response times (minutes to tens of hours), during which various polymer constituents either migrate to the surface from