An amphiphilic silicone-modified polysaccharide molecular hybrid with in situ forming of hierarchical superporous architecture upon swelling

Most hydrogels face the challenge that extensive water uptake deteriorates their mechanical integrity, which restricts potential uses and, in some cases, reduces therapeutic performance in biomedical applications. Motivated by the concept that structural optimization was able to improve the mechanical properties whilst maintaining a high water uptake, in this work we designed a new type of strong network, i.e. PDMS-crosslinked-NOCC polymer networks (PMSC CAPNs), by esterification between cross-linked PDMS diol (bis(hydroxyalkyl) terminated polydimethylsiloxane, silicone) and NOCC (N,O-carboxymethyl chitosan). By manipulating the cross-linked density with PDMS, a hierarchical structure in which PDMS-rich microgels were randomly distributed within the underlying PMSC hydrogel could be tailored through the control of polymer-polymer and polymer-solvent interactions. Besides, the resulting hybrid hydrogel displayed an efficient self-foaming capability to create in situ a hierarchical superporous microarchitecture upon swelling. The swelling behavior accounted for by Flory-Rehner theory indicated that the PDMS macromonomeric crosslinker not only caused the development of a superporous microarchitecture under solvation effects but also escalated both strength and elasticity to the final hydrogel. A new swelling model based on spectroscopic examination of the PMSC CAPNs was successfully proposed, which nicely defined the unique structural transition of the hydrogel upon swelling. We also envision the potential development of such a hybrid hydrogel for advanced biomedical applications.