Enhancing hydrogel toughness by uniform cross-linking using modified polyhedral oligomeric silsesquioxane
Sirawit Pruksawan, Jeremy Weixiong Reuben Lim, Yock Leng Lee, Zehuang Lin, Heng Li Chee, Yi Ting Chong, Hong Chi, Fuke Wang
Abstract
Abstract The use of macro cross-linkers is one of the most effective approaches for developing tough hydrogels. However, the presence of uneven cross-linking and the resulting hydrogel inhomogeneity restrict further improvement. Here, we achieve uniform cross-linking by employing polyhedral oligomeric silsesquioxane (POSS)-grafted acrylated polyethylene glycol (PEG) as a cross-linker to enhance the toughness of hydrogels. The nano-sized hard silica core of POSS facilitates energy dissipation, and its dissolved form ensures uniform cross-linking through molecular-level dispersion. The peripheral acrylate groups introduce multiple interacting points, and the physical entanglements of long-chain PEG contribute to enhanced toughness. Incorporating acrylated POSS-PEG into polyacrylamide hydrogel yields enhanced properties such as toughness of up to 6531 kJ m −3 and break elongation up to 9455%, where the length of PEG chains grafted onto POSS is demonstrated to play a crucial role in facilitating energy dissipation and achieving high toughness.