Synthetic strategies for the preparation of hydrogels using star-shaped polymers

Abstract

The development of modern and efficient polymerization techniques has enabled the successful design and synthesis of star-shaped polymers with complex and precise architectures. Star-shaped polymers are versatile and can be easily adapted to different applications, such as the innovative polymeric hydrogels with unique and optimized properties. Hydrogels prepared from star-shaped polymers exhibit enhanced mechanical properties, addressing the limitations of those produced through traditional methods, where random cross-linking leads to network inhomogeneity. In this review, we provide a comprehensive overview of the polymerization strategy used for synthesizing star polymers, multi-initiators that give rise to the number of arms, and cross-linkers, which are subsequently used to prepare polymeric hydrogels. The hydrogels prepared from star-shaped polymers were classified into four groups according to the cross-linking strategy and physicochemical properties: supramolecular hydrogels, amphiphilic polymer conetwork hydrogels, double-network hydrogels, and cross-linked hydrogels. Besides biocompatibility, hydrogel applications require advanced mechanical properties that are significantly affected by cross-linking defects introduced in the network structure during the gel preparation, limiting a large variety of hydrogel applications. To overcome this issue, incorporating star polymer into hydrogel leads to a more homogeneous structure, enhancing mechanical properties. In the last part of this review, relevant advances in hydrogels incorporating star polymers in the biomedical field are described.