Radical polymerization proceeds via highly reactive neutral radical growing species and has been investigated from various aspects for many years. It is also one of the most common and widely employed polymerizations in industy due to the high reactivity and applicability as well as the tolerance to polar compounds like water. In addition, recent years witnessed great developments in living radical polymerization, which has now been emplyed for the precision polymer synthesis. This review covers fundamental aspects in conventional radical polymerizations including polymerizable monomers, mechanisms like initiation, propagation, termination and chain transfers, and copolymerizations in addition to the recent advances in living radical polymerizations and stereospecific radical polymerizations.

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Cationic polymerizations that have supported synthesis of networked polymers involve the well-known cationic ring-opening polymerization of epoxide and the recent advance of living cationic polymerization that allows precise synthesis of polymers having reactive chain ends so that they can be applied as building blocks of networked polymers. In addition, exploitations of various naturally occurring vinyl monomers and development of new cyclic monomers as well as applications of new initiators have prompted the current expansion of the field of cationic polymerization. Herein, the current status and the future prospects of molecular design of monomers, their polymerization behaviors, and their applications to networked polymers are demonstrated.

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Polymer synthetic method is divided into chain polymerization and polycondensation. This article first explains the principles of polycondensation and then reviews recent progress of synthetic method for condensation polymers. This involes a precision polycondensation, that is, how to control i) the molecular weight distribution of condensation polymers, ii) the degree of branching of hyperbranched polymers, and iii) coupling positions of aromatic rings. In addition, the synthesis of condensation polymers with high molecular weights under nonstoichiometric balance of monomers is also introduced.

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Supramolecular polymers have been of importance as smart soft materials. This research group has been focusing on their importance and working on various types of supramolecular polymers utilizing cyclodextrins (CDs) and their derivatives as key building blocks. This article reviews some examples of stimuli-responsive networks prepared from CDs or CD derivatives in our laboratory.

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