Inspired by elastomers: fabrication of hydrogels with tunable properties and re-shaping ability via photo-crosslinking at a macromolecular level

Abstract

Conventional hydrogels cross-linked by small molecular cross-linkers usually exhibit poor mechanical properties, limiting the application of hydrogels to a certain degree. Here, inspired by the fabrication technologies of elastomers, we firstly fabricate a macromolecular hydrogel pre-polymer (MHP) via thermal polymerization and then crosslink the MHP at a macromolecular level by UV irradiation. In this novel technology, polyetheramine (PEA) plays an important role in the fabrication of crosslinked hydrogels. In the thermal polymerization stage, N–CH₃ units in PEA acted as co-initiators and grafting agents to form an MHP. Under the UV irradiation, benzophenone (BP) moieties in PEA could be excited as photo-cross-linkers. More importantly, the tensile stress of PEA5%-PAAm hydrogel could be effectively tailored from 180 kPa to 500 kPa by controlling the crosslinking degree under different irradiation times. Through this important characteristic, we could also effectively build a hydrogel with a complex three dimensional (3D) geometry, which is not easily obtained by conventional polymerization methods.