Branched polymers result in a more compact structure in comparison to linear polymers of identical molecular weight, due to their high segment density which affects the crystalline, mechanical, and viscoelastic properties of the polymer. Star polymers constitute the simplest form of branched macromolecules where all of the chains - or arm segments - of one macromolecule are linked to a centre defined as the core. Over recent years, modular ligation reactions - some of which adhere to click criteria - have enabled the synthesis of a variety of star polymers via efficient polymer-polymer conjugations. While the modified Huisgen [3 + 2] dipolar copper catalyzed azide and alkyne cycloaddition (CuAAC) has been widely employed for macromolecular star synthesis, Diels-Alder and hetero Diels-Alder reactions offer alternative pathways which allow for similarly efficient macromolecular conjugations. Moreover, combinations of these protocols afford the synthesis of more complex star polymer structures which previously had not been achievable.

Constructing star polymers via modular ligation strategies

Polymer scaffolds as drug delivery systems

Facile one-step preparation of robust hydrophobic cotton fabrics by covalent bonding polyhedral oligomeric silsesquioxane for ultrafast oil/water separation

Polyhedral oligomeric silsesquioxane (POSS)-hybrid polymers have been successfully employed as functional inorganic-organic hybrid materials for various applications due to their well-determined structures. The past 6 years has witnessed growing interest in the rational design and synthetic approaches for POSS-hybrid polymers, driven by the adoption of controlled living radial polymerization and click chemistry. This review addresses developments in the precise manipulation of POSS building blocks via atom transfer radical polymerization, reversible addition-fragmentation chain transfer, and click chemistry. Not only are the structures of POSS-hybrid polymers tunable in terms of chemical composition, molecular weight, and polydispersity, but they are also controllable in sequential and hierarchical chain topology. Finally, some representative cutting-edge applications of POSS-hybrid polymers, including biomedical and energy-related materials, fabrication of nanostructures, and functional surface coating materials, are highlighted.

Tian-jiao Wen

Papers

Synthesis of Janus POSS star polymer and exploring its compatibilization behavior for PLLA/PCL polymer blends