The research on advanced functional polymers is being driven by the fast-growing demand for new functional materials that can be used in revolutionary technologies. Polymers can be endowed with functions by using certain special preparation methods or by introducing functional groups or fillers into materials. These functions are either intrinsically possessed by materials or actuated by external stimuli. In this review, we present an overview of the recent developments made in the research hotspots of functional polymers, encompassing polymerization methodologies, luminescent polymers, photovoltaic polymers, other electronic and optical polymers (including low-k polyimides and second-order nonlinear optical polymers), biorelated polymers (particularly those for biomedical applications), supramolecular polymers, stimuli-responsive polymers, shape-memory polymers, separation polymer membranes, energy storage polymers, and covalent organic framework polymers. The concepts, design strategies at the molecular level, preparation methods, classifications, properties, potential applications, and recent progress made in such polymers are summarized. Challenges and future perspectives of each type of functional polymers are also addressed, including research efforts regarding the design and fabrication of functional polymers for serving the increasing demand for new materials.

Coumarin, a traditional perfume substance, serves as a photosensitive crosslinker to construct a polyurethane network. Upon mechanical damage or ultraviolet illumination at a wavelength of 254 nm, the coumarin dimers on the fractured surface that link the polyurethane backbones with one another are cleft, and can be reconnected via irradiation at 350 nm. By using this feature, cracks on the polymer are mended by ultraviolet exposure or even sunlight without the aid of any catalyst. Owing to the reversibility of the photocyclization of coumarin moieties, multiple cycles of crack mending are allowed, as demonstrated by both qualitative and quantitative characterization. This repeated photo-remendability enables the polyurethane to heal the same site in the material more than once, which is of value for practical applications.

Repeated self-healing, reshaping and recycling of a transparent crosslinked polyurethane are enabled by a sunlight triggered reversible disulfide exchange reaction.

Vulcanized rubber made from an industrial formula can be healed and reclaimed by activating the rearrangement of the inherent sulfur crosslinked networks under the catalysis of CuCl₂.

Crosslinked polyacrylate is self-healed and reprocessed through rearrangement of networks based on catalyst-free dynamic exchange of aromatic Schiff base bonds.