Postpolymerization Modification: A Powerful Tool for the Synthesis and Function Tuning of Stimuli‐Responsive Polymers

Stimuli‐responsive polymers are a type of functional polymers showing a change in their physicochemical properties in response to external stimuli, such as temperature, pH, and electrochemical potential application, and they can be used in biosensors, biomedicine, and separation technology. Postmodification of polymers plays an important role in designing stimuli‐responsive polymers in terms of their synthesis, tuning of their thermoresponsivity, and functionalization. A variety of topological polymer structures, such as a comb, sphere, and dendrimer, can be produced, and the resultant tuning of the transition temperatures and phase types (lower critical solution temperature‐ or upper critical solution temperature‐type) can be achieved. Furthermore, postmodification techniques are employed as a useful tool to functionalize precursor polymers or improve the responsive properties of the polymers, which expands the applicable fields of these polymers. In this review, click chemistry‐related reactions, the esterification reaction, and surface‐initiated polymerization are the focus as efficient postmodification reactions to produce high‐performance stimuli‐responsive polymers. Postpolymerization modification using highly efficient chemical reactions, such as click reactions, is a useful technique to prepare a variety of stimuli‐responsive polymers and materials. Appearance of new stimuli‐responsiveness is derived from the functional side chain units. In addition, the balance of hydrophilicity and hydrophobicity of polymers is tuned by postmodification reactions, leading to complex phase transition behavior.